THE AUSTRALIAN NATIONAL UNIVERSITY _________________________________________________________________________________

Research School of Biology Division of Evolution, Ecology & Genetics CANBERRA ACT 0200 AUSTRALIA TELEPHONE: +61 26 125 2873 FACSIMILE: +61 26 125 5573 EMAIL: penelope.gullan@anu.edu.au 7 February 2014

To whom it concerns, Dr Gabor Neumann has asked me to provide documentation on the identity of dead, preserved lac insects (order Hemiptera, superfamily Coccoidea, family Kerriidae; formerly Tachardiidae) that were sent to me for taxonomic identification. All specimens from Australia (Christmas Island) and Malaysia (Klang in Selangor and Sarawak in Borneo) have morphology consistent with that of Tachardina aurantiaca (Cockerell), which is a common species in Southeast Asia. This species was named and described in 1903 from specimens collected on citrus in Java, Indonesia. Subsequent publications record this species from Australia (Christmas Island), Malaysia, the Maldives, Singapore and Thailand. All other species of the genus Tachardina occur in Africa and thus it is relatively easy to distinguish T. aurantiaca from other lac insects present in Southeast Asia. The only published taxonomic descriptions and illustrations of T. aurantiaca that are useful for morphological identification are by Chamberlin (1923) and Lit (2002). The latter is an unpublished chapter in a PhD thesis of one of my former students. I identified the adult female specimens from Christmas Island and Malaysia by examination of the insect cuticle (“skin”) under a compound microscope. This required the body contents of the specimens to be cleared (removed) by soaking for 24 hours in 10% potassium hydroxide, and then the cleaned cuticles were stained and dehydrated before being mounted in a resin on a microscope slide. The features useful for identification can only be seen under high magnification on the compound microscope. Tachardina aurantiaca is distinguished from other lac insects by a combination of morphological features, including the four-sectored anal ring, the presence of two secondary depressions on the brachial plate and the shape and composition of the marginal duct clusters. There had been no recent collection and study of T. aurantiaca until the work of Dr Neumann and his colleagues and associates. Regards,

Dr P.J. Gullan Emeritus Professor Literature cited Chamberlin, J.C. (1923) A systematic monograph of the Tachardiinae or lac insects (Coccidae).

Bulletin of Entomological Research 14: 147–212. Lit, I.L., Jr (2002) Morphology, Systematics and Phylogeny of the Lac Insects (Kerriidae,

Coccoidea, Hemiptera). Doctor of Philosophy thesis, University of the Philippines Los Baños, Philippines. 286 pp.

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RESEARCH AND DEVELOPMENT OF BIOLOGICAL CONTROL FOR 

SCALE INSECTS:  INDIRECT CONTROL OF THE YELLOW CRAZY 

ANT ON CHRISTMAS ISLAND, 2009‐2013 

 

 

Peter T. Green, Dennis J. O’Dowd, Gabor Neumann, and Sarah Wittman 

Department of Botany, La Trobe University, Bundoora, Vic 3086 

 

 

 

 

 

 

 

Final Report to the Director of National Parks 

3 July 2013 

 

 

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Executive Summary 

Research Project 1.  YCA dependence on honeydew 

Project 1a.  Honeydew use by YCA.  Successful biological control of the yellow lac scale Tachardina 

aurantiaca could remove a large fraction (an average of 70% to an average of 87%, depending on 

assumptions) of honeydew available to the yellow crazy ant.  However, there is considerable site‐to‐

site variation in the likely contribution of T. aurantiaca to the total honeydew economy, and it is not 

certain that targeting this species alone would provide adequate indirect control for the YCA in all 

supercolonies.  The most prudent course of action is to target the entire assemblage of honeydew‐

producing scale insects through the introduction of a biological control agent for T. aurantiaca, 

complemented by the use parasitoids already present on Christmas Island to target the coccoid soft 

scales.   

 Project 1b.  Stable Isotope Analysis.  Stable isotope analyses of YCA workers, plants, herbivores and 

predators collected from four declining supercolonies in 2010‐2011 indicate that at supercolony 

densities, a substantial fraction of YCA dietary intake is plant‐derived.  This is consistent with the idea 

that YCA supercolonies depend heavily on honeydew derived from scale insects for a large fraction 

of colony food and energy requirements, and provides support for the idea that indirect control over 

YCA supercolonies could be achieved by targeting honeydew‐producing scale insects for biological 

control.  

 Project 1c. Scale Insect Removal Experiment.  The exclusion of YCA from access to scale insects at a 

large experimental field site caused YCA activity on the ground to decline 5‐fold within 4 weeks, 

compared to pre‐treatment levels.  This large field experiment validates the key concept of indirect 

biological control for YCA on Christmas Island; exclusion of honeydew‐producing scale insects from 

YCA caused a significant and substantial reduction in YCA abundance on the ground. 

Project 1d. Carbohydrate supply and YCA growth and behaviour.  Dynamics and behaviour of YCA in 

laboratory colonies depended on carbohydrate supply.  When sugar supply was elevated, 

reproductive output by queens increased, death rates of workers decreased, foraging tempo 

quickened, and interspecific aggression intensified.  These results suggest that sugar supply, through 

honeydew supplied from scale insects, plays an important role in YCA supercolony dynamics, 

foraging efficiency, and interspecific aggression. 

 

Research Project 2.  Scale insects and natural enemies 

Projects 2a and 2c. Natural enemies survey, parasitization rates of lac scale insects (Tachardina 

aurantiaca and Paratachardina pseudolobata) and parasitoid behaviour in area of origin 

(Southeast Asia) and on Christmas Island.  Few natural enemies of the key honeydew‐producing 

scale insect Tachardina aurantiaca occur on Christmas Island, and they do not regulate its population 

size. No parasitoids of female T. aurantiaca were found. Conversely, within its native range in 

Malaysia, T. aurantiaca is rare and patchily distributed, associated with diverse natural enemies, 

including at least five species of primary parasitoids, and it suffers high parasitization rates – all 

attributes consistent with population regulation by natural enemies.  Importantly, high parasitism 

rates in Malaysia occurred in the presence of honeydew‐collecting ants, including the yellow crazy 

ant.  Of the primary parasitoids known to attack yellow lac scale from our studies in Malaysia, 

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Tachardiaephagus somervillei (Encyrtidae) is the most promising agent for introduction and release 

on Christmas Island.  All Tachardiaephagus species have a narrow host range and appear to be family 

specialists, known only to attack the Kerriidae, the family to which the yellow lac scale belongs (Table 

3).  Our initial studies indicate that (a) T. somervillei attacks T. aurantiaca across 1900‐km range in 

Peninsular Malaysia and Malaysian Borneo, (b) is the most abundant natural enemy of T. aurantiaca, 

(c) has a short life cycle compared to its host, (d) exhibits superparasitism (i.e., where multiple 

progeny emergence from a single host individual); (e) causes high rates of parasitism on T. 

aurantiaca in the presence of tending ants, including the yellow crazy ant, and (f) can be reared 

under laboratory conditions.  Coccophagus ceroplastae and Encyrtus infelix, both parasitoids of a 

wide variety of coccid scale insects, are already present on Christmas Island. The three parasitoids T. 

somervillei. C. ceroplastae and E. infelix could be deployed in combination against the entire 

assemblage of honeydew‐producing scale insects in YCA supercolonies.

Project 2b. Scale insect survey on Christmas Island (biology, host range, habitats, natural history, 

identification).  No native or endemic scale insect species have been discovered in intensive and 

extensive searches for scale insect species on Christmas Island.  However, 400 hours of search over 

two years did yield five additional exotic scale insect species previously unknown to the island.  

Assuming that any prospective biological control agent for Tachardina aurantiaca on Christmas 

Island would be a narrow family specialist (Kerriidae) and all known scale insect species are non‐

native and invasive, the probability of any direct non‐target effects is negligible. 

Project 2d. Genetic and morphological matching between Tachardina aurantiaca and Paratachardina 

pseudolobata on Christmas Island and Southeast Asia.  The single population of T. aurantiaca on 

Christmas Island matches morphologically and genetically those populations examined so far within 

its native region in Southeast Asia.  This establishes the identity of Tachardina aurantiaca on 

Christmas Island, making the successful establishment on Christmas Island of a biological control 

agent that attacks T. aurantiaca in its native range more likely.  Further collections and analyses of T. 

aurantiaca in Eastern Malaysia (Sabah) and exploration in southern Thailand should establish if any 

morphological or genetic variation occurs across its native distribution in Southeast Asia. 

Project 2e. Scale population dynamics, especially the ecology of lac scale, Tachardina aurantiaca.  The 

life cycle of Tachardina aurantiaca is relatively long for a scale insect but several overlapping 

generations occur in a single year.  Female size is significantly correlated with fecundity, indicating 

that conditions that affect female size are likely to have a strong influence on population growth 

rates and density.  The role of males in reproduction is not yet clear although it appears that some 

females can reproduce parthenogenetically. All of these attributes will influence host‐parasitoid 

dynamics on Christmas Island. 

 

Research Project 3.  Strategic planning for biocontrol introduction 

Project 3a.  Planning research in step with legislative and regulatory requirements for biological 

control introductions.  Two regulatory frameworks govern the importation and release of an exotic 

biological control agent on Christmas Island.  To gain approval to import and release a biological 

control agent on Christmas Island, we will need to prepare and submit two sets of documents:  an 

Approvals Package under the DAFF protocol and an Environmental Referral to EACD, DSEWPaC.   The 

key government contacts involved in the two frameworks are described and currently consulting 

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each other. 

Project 3b.  Identification and agreement with co‐operators.  Collaborations have been established 

with researchers with expertise in the systematics, biology, and molecular genetics of scale insects, 

taxonomy of microhymenopteran parasitoids, and biological control of scale insects.  Cooperative 

agreements have been established with the Forestry Research Institute of Malaysia (FRIM) and 

Sarawak Forestry that provide benchspace and technical assistance.  Dr Neumann is serving as an 

advisor of a Masters student (Universiti Sains Malaysia, Penang) who is conducting research on this 

project at FRIM.  Research and collecting permits have been obtained from the States of Sarawak 

and Sabah, as well as a national collecting permit.   

Project 3c.  Safety and sanitary protocols anticipating a pre‐release environmental assessment of 

introduction.  An agreed, peer‐reviewed host list and host specificity protocol has been prepared for 

evaluating the risk of introducing T. somervillei to Christmas Island to control the invasive yellow lac 

scale, Tachardina aurantiaca.  It is recommended that host specificity testing be conducted in the 

area of origin of Tachardina aurantiaca.  A protocol for ensuring that hyperparasitoids are not 

accidentally co‐introduced with importation of T. somervillei to Christmas Island has also been 

prepared. 

Project 3d.  Rearing, release and monitoring protocols.  The requirements to establish a founder 

population of Tachardiaephagus in Malaysia free of pathogens and hyperparasites, to import this 

population under permit to Christmas Island, to establish and expand this population in a mass‐

rearing facility on Christmas Island have all been identified.  An agreed protocol for the rearing and 

release of biological control agents, and pre‐ and post‐release monitoring for their efficacy in 

controlling target scale insects and reducing densities and impacts of the invasive yellow crazy ant 

Anoplolepis gracilipes has also been prepared. 

 

   

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Introduction  

Background to the Program  

Biology and Impacts of the Yellow Crazy Ant on Christmas Island. Anoplolepis gracilipes (the yellow 

crazy ant, YCA) is a ‘tramp’ species that has become invasive throughout the tropics (Wetterer 2005). 

The YCA is listed by the IUCN as one of the world’s 100 worst invasive species (Lowe et al. 2000), and 

was accidentally introduced to Christmas Island between 1915 and 1934 (O’Dowd et al. 1999).  Because 

of its negative impacts on species, interactions and ecosystem processes, YCA is recognised as the most 

significant and pervasive threatening process affecting biodiversity on Christmas Island, reflected by the 

listing of the Loss of biodiversity and ecosystem integrity following invasion by the Yellow Crazy Ant on 

Christmas Island, Indian Ocean as a Key Threatening Process under the EPBC Act 1999, and as identified 

in Threat abatement plan to reduce the impacts of tramp ants on biodiversity in Australia and its 

territories (Commonwealth of Australia 2006).  The control of this ant features prominently in many 

Recovery Plans for EPBC‐Listed species on Christmas Island, and has been the focus of natural resource 

management activities on the island for more than a decade at the cost of millions of dollars.  

The attribute that makes the YCA so problematic on Christmas Island and elsewhere is its capacity to 

form high‐density, expansive ‘supercolonies’.  Many tramp ant species form supercolonies, often 

defined using a combination of criteria including genetic relatedness, intraspecific behavioural 

interactions, and ant abundance.  For example, the invasive argentine ant Linepithema humile is 

genetically uniform across most of its European range and is regarded as a single supercolony (Giraud et 

al. 2002), while intercontinental behavioural assays and analyses of cuticular hydrocarbons suggest this 

species may form a single supercolony spanning Australia, Europe, North America and Japan (Sunamura 

et al. 2009; Suhr et al. 2010).  Although two distinct genotypes of YCA occur on Christmas Island, these 

co‐occur at very small spatial scales (Thomas et al. 2010) and behavioural assays pairing individual ants 

from opposite ends of the island suggest that the population on Christmas Island behaves as a single 

supercolony (Abbott 2005).  Nevertheless, YCA supercolonies on Christmas Island have always been 

defined in terms of very high ant densities.  YCA occurred at many locations across the island in very low 

abundance with no obvious impact on biodiversity, but in 1989, and then again in late 1997, YCA was 

discovered in several locations at extremely high densities sufficient to extirpate local populations of the 

abundant red land crab Gecarcoidea natalis (O’Dowd et al. 1999, 2003).  The red crab is a keystone 

species in rainforest on the island that controls patterns seedling recruitment and rates of litter 

breakdown and nutrient cycling (Green et al. 1997, 1999, 2008).  Since then, the density at which YCA 

kills land crabs leading to understorey transformation has become the operational definition of 

‘supercolony’ on Christmas Island.  On the ground, the density of YCA in supercolonies can be 

extraordinary – up to several thousand per square meter (Abbott 2005).  A systematic, island‐wide 

survey in 2001 found multiple supercolonies ranging in area from tens to hundreds of hectares, totalling 

c. 2500 ha, or 25% of rainforest on the island (Green et al. 2004; Green and O’Dowd 2009).  

Supercolonies have continued to form and reform; upwards of 5000 ha of rainforest have been treated 

with toxic bait to 2012. 

The key trait that has allowed YCA to form high‐density supercolonies is its ability to form mutualistic 

associations with honeydew‐producing hemipterans, principally scale insects (O’Dowd et al. 2003; 

Abbott and Green 2007).  The scale insects suck sap from trees and secrete carbohydrate‐rich 

honeydew on which the ants feed. The ants provide sanitation services for the scale insects, removing 

honeydew that might otherwise build up and kill them either through asphyxiation or the growth of 

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sooty moulds, but the ants may also provide limited protection for the scale insects from generalist 

natural enemies.  Supercolony‐level densities of YCA and outbreak‐densities of several species of scale 

insects invariably co‐occur (Abbott 2004), and in supercolonies high densities of ants can typically be 

seen ascending the boles of most trees to tend scale insects in the canopy.  The gasters of descending 

ants are swollen with carbohydrate‐rich honeydew that they take back to the nest to share with non‐

forager conspecifics.  Site‐scale, manipulative experiments on Christmas Island have demonstrated a 

causal link between co‐occurring high densities and ants and scale; the exclusion of ants using toxic bait 

leads to a dramatic decline in scale abundance (Abbott and Green 2007).  Part of the current project 

was to determine if this link is bi‐directional, that is, if the exclusion of scale insects from the ants leads 

to a dramatic decline in ant density (see Project 1c, below).  On Christmas Island YCA interacts with 

several species of honeydew‐secreting scale insects including Tachardina aurantiaca, the principal 

target of the biocontrol program (see below).  

The mutualism between YCA and scale insects has manifold negative impacts on species abundances, 

interactions among species, and forest structure.  At the core of these impacts is the devastating effect 

of YCA on land crabs, especially red crabs.  YCA sprays formic acid as a weapon both to subdue prey and 

in self‐defence, and although the amount sprayed by individual ants is tiny, at supercolony densities the 

overall effect is overwhelming.  YCA supercolonies reduce formerly high densities of red crabs 

(averaging c. 0.5 – 1.0 crabs m‐2) to nil, deregulating seedling recruitment and litter dynamics and 

resulting in a thick, diverse understorey of seedlings and saplings with an almost permanent layer of leaf 

litter (O’Dowd et al. 2003).  In forest dominated by red crabs, the understorey is sparse and dominated 

by a few crab‐resistant species, and the forest floor is almost devoid of litter for much of the year 

(Green et al. 1997, 1999, 2008).  These impacts are widespread.  Based on the spatial extent of 

supercolony formation over the last 12 years, it is likely that YCA has extirpated at least 20 million red 

land crabs, or about 30% of the total population in areas where they have formed supercolonies.   

YCA has also caused declines in the density of red land crabs at sites where high‐density supercolonies 

have never formed.  About half of the red crab population migrates to the coast each year to complete 

breeding activities, and many YCA supercolonies have formed across traditional crab migration routes.  

Thus, significant numbers of migrating red crabs have been killed en route to the coast over many years, 

never to return to their former home ranges.  As a result, some areas of rainforest are practically devoid 

of red crabs even though YCA supercolonies have never occurred there, and the same processes of 

understorey transformation are in train there too.  It is hard to gauge the severity and extent of this 

“ghosting” effect because pre‐YCA invasion data on red crab densities are sparse.  It is likely to be 

significant; Green et al. (2011) estimated that around 25% of rainforest may have been ghosted at some 

time in the last decade.  The direct and indirect (ghosting) impacts of YCA supercolony formation have 

been so widespread since the late 1990s that just 28% of rainforest could still be considered as “intact” 

(i.e. no YCA supercolony formation and unaffected by ghosting) by 2007 (Green et al. 2011).   

In YCA supercolonies, scale insects themselves can have large negative impacts on their host plants.  

Especially vulnerable is the Tahitian Chestnut Inocarpus fagifer, a widespread canopy tree that hosts 

very high densities of Tachardina on its outer twigs and leaves.  In supercolonies, seedlings, saplings and 

small trees all suffer extremely high mortality, and the canopies of large trees are much reduced 

through the dieback of fine twigs and branches (Green et al. 2001, O’Dowd et al. 2003, P. Green and D. 

O’Dowd, unpublished results).  There is also evidence that fruit production is reduced in supercolonies.  

Excess honeydew that YCA does not harvest, or which the scale insects deliberately flick off, settles on 

7

leaves of all plant species and is colonised by sooty moulds, which probably interferes with 

photosynthesis and growth.   

YCA may affect many of the island’s bird species through direct interference and through altered 

resource availability and habitat structure (Davis et al. 2008). The Christmas Island Emerald Dove 

Chalcophaps indica natalis is 9‐14 times less abundant in ant‐invaded forest, and because it forages on 

the forest floor, is probably vulnerable to direct predation by YCA.  The nesting success and density of 

juvenile Christmas Island Thrushes Turdus poliocephalus erythropleurus is lower in supercolonies, where 

they also show altered foraging and reproductive behaviours.  Furthermore, these birds alter their 

choice of tree species in which to build nests, with lower frequency on tree species that typically 

experience high densities of scale insects and ants.  The density of foraging Christmas Island white‐eye 

Zosterops natalis is higher in supercolonies, perhaps because scale insects (as prey) are more common 

there.  It is possible that impacts of YCA on thrushes and white‐eyes affect frugivory and seed dispersal 

on the island; assays with both real and model fruit showed handling rates to be more than two‐fold 

lower in YCA supercolonies, and manipulative experiments showed this to be a direct consequence of 

the presence of ants (Davis et al. 2009).  There is no evidence that YCA supercolony formation 

significantly affects the density of nesting success of Abbott’s Booby Papasula abbotti (P. Green, 

unpublished data), while the impact of YCA on other seabirds and on other land birds such as the 

goshawk and owl are unknown.   

Several endemic vertebrate species, including the pipistrelle bat Pipistrellus murrayi and endemic 

reptiles have experienced precipitous declines over recent years, but the causes of the declines are 

enigmatic.  In the case of the pipistrelle it is possible that YCA supercolony formation has contributed to 

the decline, either directly through predation of bats at roost sites or indirectly by eliminating red crabs 

and facilitating the expansion of predators such as giant centipedes Scolopendra subspinipes, wolf 

snakes Lycodon aulicus, cats and rats (Schulz and Lumsden 2004, Lumsden et al. 2007, Beeton et al. 

2010).  However, the decline of the pipistrelle was well in train before the rise of YCA supercolonies in 

the late 1990s.  The endemic reptiles were similarly in decline long before YCA supercolonies became 

common, and the role of YCA in their decline is also uncertain (Smith et al. 2012). 

In addition to impacts on species of concern, supercolony formation by YCA has also led to an altered 

web of species interactions that facilitates the entry, spread, and abundance of other invasive species.  

The best example of this is the entry and spread of the giant African landsnail Achatina fulica (GALS) in 

rainforest on the island.  GALS was introduced to the island in the 1940s, and despite being a 

notoriously invasive species (Lowe et al. 2000), its distribution was for many decades limited to settled 

areas, abandoned mining fields and roadsides.  Experiments showed that predation by red crabs 

excluded this invader from establishing in rainforest (Lake and O’Dowd 1991), but the extirpation of red 

crabs in YCA supercolonies, coupled with the ability of GALS to coexist alongside YCA in supercolonies, 

has permitted this snail to establish high densities in rainforest at many locations across the island 

(Green et al. 2011).  The facilitation of GALS by YCA could be due to the creation of enemy‐free space, 

augmented understorey resources, or both. 

The rise of YCA supercolonies and the extirpation of red crabs have also affected the invasion dynamics 

of other non‐native organisms.  These effects encompass both inhibition and facilitation for a range of 

non‐native ant and snail species (O’Dowd and Green 2010; P. Green and L. O’Loughlin, unpublished 

results), while invasion by several weeds including Capsicum frutescens, Carica papaya, Cordia 

curassavica, and Muntingia calabura appears to be facilitated in areas affected by YCA supercolony 

formation (P. Green and D. O’Dowd, personal observations).   

8

Management.  Given all of the above, supercolony formation by YCA is considered a major and on‐

going threat to biodiversity values on Christmas Island.  To date, the management of YCA has depended 

on surveillance, monitoring, and control using toxic bait (Green and O’Dowd 2009, Boland et al. 2011).  

New supercolonies continue to form, and there is concern for the sustainability of this program in terms 

of its expense, non‐target impacts, and the resources it diverts from other conservation programs 

(Beeton et al. 2010).  Further, this program can only ever be reactive, and it has not been able to find an 

effective solution to the difficult issue of the management of incipient supercolonies, where YCA density 

is high enough for them to monopolize the toxic bait, making the risk of non‐target impacts too high to 

justify the treatment of these areas.  There is widespread agreement that the development of a more 

cost‐effective, sustainable alternative to the use of toxic bait is needed to manage the YCA invasion on 

Christmas Island (Beeton et al. 2010). 

Ten years ago, O’Dowd and Green (2003) suggested that long‐term, sustainable suppression of YCA 

supercolonies could be achieved using biological control agents.  Classical biological control works on 

the principle that in their area of origin, populations of native species are kept in check by their natural 

enemies (predators, parasites or pathogens).  There is a large body of literature demonstrating that in 

many cases, species introduced outside of their native ranges become invasive because they have 

effectively left their enemies behind.  This is known as the “Enemies Release Hypothesis”.  The principle 

of classical biological control then is the converse:  to re‐establish population control over invasive 

species by first identifying and then importing a natural enemy – a biological control agent – from within 

the native range of the target organism.  In all instances, this now involves selection and testing of 

biological control agents to verify narrow host ranges that minimize the risk of non‐target impacts in the 

area of introduction. 

Indirect Biocontrol for YCA on Christmas Island.  Despite the diversity and significant ecological 

and economic impacts of invasive ants worldwide, they have proved to be an especially difficult target 

group for biological control.  Although a program for the biocontrol of the Red Imported Fire Ant 

(Solenopsis invicta) using a parasitic fly and a protozoan disease as agents is currently under 

development in the southeastern United States, no species of ants have yet been successfully controlled 

in the field using biological control agents and principles.  Instead, O’Dowd and Green (2003) proposed a 

novel solution for managing the YCA invasion; rather than targeting the ant itself, biological control 

could target the key mutualist species (honeydew‐producing scale insects) that are likely to play a 

significant role in sustaining YCA supercolonies at very high and ecologically damaging densities.  Long‐

term, sustainable suppression of YCA supercolonies could be achieved through the introduction of a 

biological control agent that would indirectly affect YCA by reducing carbohydrate supply provided by 

honeydew‐producing scale insects, a key resource implicated in supercolony dynamics. 

The Biocontrol Project 2009 – 2013.  Funding for a four‐year program of research and development 

to progress the concept and feasibility of indirect biocontrol was allocated in the Australian Federal 

Budget 2007/08, as part of a broader, 10‐year plan for the control of YCA on Christmas Island.  We 

proposed a research project with three overarching questions: 

1. Do YCA depend on honeydew‐producing scale insects? 2. Which species of honeydew‐secreting scale insects occur on Christmas Island, and are appropriate 

natural enemies for scale insects available for introduction? 

3. What regulatory frameworks govern the implementation of a biological control program on 

Christmas Island, an external territory of Australia? 

9

 

Two Postdoctoral Fellows were employed to perform most of the research under Questions 1 & 2.  Dr. 

Sarah Wittman was recruited from the University of Vermont in the United States, with a project brief 

to establish the dependence of YCA on honeydew‐producing scale insects.  She arrived on Christmas 

Island in November 2009, and finished in December 2012.  She is currently back in the United States 

working on the preparation of manuscripts for publication arising from her work.  Dr. Gabor Neumann 

was recruited from the USDA‐ARS in Hilo, Hawaii as a biocontrol practitioner, with a project brief to 

investigate the scale insects of Christmas Island, to describe their local suite of natural enemies, and to 

search for suitable biocontrol agents in Southeast Asia.  His tenure on this contract expires in July 2013. 

 

The biocontrol project was overseen by an independent steering committee, the Christmas Island Crazy 

Ant Scientific Advisory Panel (CASAP), which comprises scientists, managers, and policymakers.  CASAP 

provided expert advice and reviewed progress through panel meetings and evaluation of interim and 

annual reports.  

 

Structure of the Final Report.  The broad research questions (above) were refined into three 

“Research Projects” and 13 subprojects, that were listed as Services in the Schedule to the Contract 

between the Director of National Parks and La Trobe University, signed on 29 January 2009.  Below, we 

report against these subprojects as they are laid out in the Contract Schedule, and provide an 

introductory rationale for each using text (in italics) copied from the original Schedule.  

   

10

Research Project 1.  YCA dependence on honeydew  

Numerical dominance and impacts of invasive ants may be sustained by their association with 

honeydew‐secreting Hemiptera.  For example, ~1/2 of the energy supply of the red imported fire 

ant is obtained from honeydew secreted by Hemiptera and ecologically dominant ants in the 

rainforest canopy are highly dependent on honeydew.  How dependent is the YCA on honeydew 

obtained from scale insects and is honeydew critical to population size?  Research outlined 

below is directed at estimating the use and sources of honeydew by the YCA on Christmas 

Island, the importance of carbohydrates in its diet, and the role of honeydew in sustaining high 

populations. 

 

Project 1a.  Honeydew use by YCA 

Mutualisms between invasive ants and Hemiptera may drive positive population growth leading to 

numerical dominance of ants.  This project will give a quantitative picture of honeydew use by the YCA 

and focus on the relative importance of the lac scale Tachardina aurantiaca and soft scale Coccus spp. as 

sources of honeydew.  Knowledge of the importance of honeydew derived from lac scale is critical since 

in the first instance they are the proposed target of biological control. 

Research Findings 2009‐2013 

The original intention of this project to combine data on per capita honeydew production by the most 

important (common) honeydew‐producing scale insects, analyses of the quality of honeydew (sugars and 

their concentrations), and estimates of scale abundance and YCA visitation rates to estimate empirically 

the ‘honeydew economy’ of YCA supercolonies, and the relative contribution of Tachardina to that 

economy.  However, collecting sufficient honeydew for analyses using glass microcapillary tubes proved 

technically very challenging, there were also issues (packaging, quarantine) of transporting fresh samples 

to our preferred analytical laboratory in Melbourne.  The logistics of collecting spatially and temporally 

replicated data on YCA visitation rates to scale insects using video recordings was also extremely 

challenging. 

Instead, we devised an indirect measure of the honeydew economy, called the Site Honeydew Index 

(SHI).  The SHI is a relative estimate of the total volume of honeydew that could be produced at a site.  It 

is a compound measure that considers the capacity of different plant species to host either Tachardina 

aurantiaca, or coccoid honeydew‐producing species of soft scale insects, together with tree size and tree 

abundance.  The basis of the SHI is canopy surface area, generated for each tree using published 

allometric equations that predict crown dimensions from stem diameter (Poorter and Bongers 2006). 

Presumably, large trees have the capacity to host more scale insects, and canopy surface area is 

preferable to canopy volume because scale insects live on leaves and thin twigs of the outer canopy.  This 

estimate is then multiplied by the average abundance of scale insects per unit length of stem, using host 

species‐specific data for both Tachardina and soft scales (data from Table 4.3 in Abbott 2004).  The SHI is 

the sum of these products, divided by 10000 for convenience.  Thus, the SHI is the sum of the 

contributions from individual trees for both Tachardina and soft scales, weighted by tree size (canopy 

surface area) and species identity.  SHIs were calculated for 10 50 m x 50 m plots in YCA supercolonies, 

on which all trees ≥ 5 cm dbh were enumerated in June‐October 2000 (P. Green, unpublished data).  The 

SHI varied 1.6‐fold (from 78 to 125) suggesting that the capacity of forest stands to support YCA 

supercolonies varies considerably.  Tachardina is estimated to contribute a large fraction of the 

11

honeydew economy at forest sites with YCA supercolonies (mean = 70%, range 46‐86%; blue symbols in 

Fig. 1).  This assumes per capita parity in the quantity and quality of honeydew produced by Tachardina 

and the coccoid soft scales species.  However, adult female Tachardina are much larger than the adult 

females of the coccoid species, and its reasonable to suppose that per capita honeydew production is 

much higher in Tachardina.  Assuming a three‐fold higher rate of honeydew production, Tachardina may 

contribute a mean of 87% to the SHI (range 72 – 95%; red symbols in Fig. 1).  Successful biological control 

of the yellow lac scale Tachardina aurantiaca could remove a large fraction of honeydew available to the 

yellow crazy ant.  One caveat to this conclusion is that the balance between the contributions made by 

Tachardina and the coccoid soft scales to the total honeydew economy may have declined over time at 

some sites where supercolonies have reformed after baiting.  Inocarpus fagifer is a key host species for 

Tachardina in YCA supercolonies; just this single species contributed an average of 50% to the Tachardina 

component of the SHI in 2000.  The species is so heavily utilised by Tachardina and YCA that significant 

tree mortality occurred in supercolonies between 2000 and 2002 on the 10 50 x 50 m tree census plots 

(P. Green, unpublished data).  Although these supercolonies were destroyed by the aerial baiting 

campaign of 2002 (Green and O’Dowd 2009) and YCA supercolonies have not reformed on these sites 

since (D. Maple, unpublished data), a targeted recensus of Inocarpus on 8 plots in 2012 showed some 

further dramatic declines, possibly caused by Tachardina tending by the ant Camponotus sp. in the 

decade after baiting.  The death of many mid‐ to large‐sized Inocarpus trees has resulted in a decline of 

that species’ contribution to the SHI by an average of 50% (range 11 – 91%; Fig. 2). The implication of this 

finding is that where contemporary YCA supercolonies have reappeared at former but baited YCA 

supercolony sites, the new supercolonies may now be supported to a greater extent by soft scales, and 

because of that, the introduction of a parasitoid against Tachardina may be less effective in those 

locations. The extent of this issue could be estimated from the Island‐Wide Survey data by determining 

the proportion of supercolonies that reform, and the proportion of time supercolonies occupied each 

site. 

 

Key Research Outcome:  Successful biological control of the yellow lac scale Tachardina aurantiaca could 

remove a large fraction (an average of 70% to an average of 87%, depending on assumptions) of 

honeydew available to the yellow crazy ant.  However, there is considerable site‐to‐site variation in the 

likely contribution of T. aurantiaca to the total honeydew economy, and it is not certain that targeting 

this species alone would provide adequate indirect control for the YCA in all supercolonies.  The most 

prudent course of action is to target the entire assemblage of honeydew‐producing scale insects through 

the introduction of a biological control agent for T. aurantiaca, complemented by the use of parasitoids 

already present on Christmas Island to target the coccoid soft scales.     

12

Project 1b.  Stable Isotope Analysis 

Analyses of Nitrogen (N) isotope ratios show that ecologically dominant ants and many invasive 

ants obtain little N through predation and scavenging, but feed primarily as herbivores, deriving 

carbohydrate through exudates produced by Hemiptera, primarily scale insects.  This project 

will use this widely accepted technique to determine N and C stable isotope ratios of the YCA, 

other ant species, and known primary producers, herbivores, and predators to characterize how 

much of the dietary requirements of the YCA is derived from plant‐derived carbohydrates and 

how this changes with invasion dynamics. 

Research Findings 2009‐2013 

Honeydew from scale insects is essentially plant sap that has passed through the bodies of scale insects, 

so when feeding on honeydew YCA are essentially acting as herbivores.  If YCA at supercolony densities 

derive most of their dietary intake from scale insects, then stable isotope analysis of their body parts 

(δ15N) should indicate a mainly herbivorous diet, while YCA at non‐supercolony densities should show a 

less herbivorous diet. 

We estimated the change in trophic position of YCA at four sites (Island Wide Survey points) as the 

abundance of ants declined from supercolony to non‐supercolony densities.  YCA workers were sampled 

6 to 8 times over a 16‐month period (April 2010 – September 2011).  Trophic position was calculated 

from mixing models that considered site‐specific stable isotope ratios of known plants, herbivores (stick 

insects), and carnivores (spiders).  All samples were analysed by a commercial company, Natural 

Isotopes, in Perth, Western Australia.   

Stable isotope analyses showed that trophic position increased (i.e. YCA became more carnivorous) as 

population densities decreased over 16 months (Site 206, R2 = 0.75, P = 0.025; Site 318, R2 = 0.67, P = 

0.025; Site 403, R2 = 0.58, P = 0.046, Site 582, R2 = 0.72, P = 0.033)(Fig. 3). This result suggests that a 

waning carbohydrate supply, as indicated by an upward shift in the trophic position of YCA, is associated 

with supercolony decline.  A series of YCA collected over two years from 10 supercolonies in 2000‐2002 

were also analyzed for δ15N after storage in ethanol for over a decade.  Unlike the four sites above, δ15N 

values and YCA abundance were not negatively correlated at three supercolonies that declined to zero 

over the period.  However, as expected, δ15N values for the other seven supercolonies with 

consistently high YCA densities did not vary over time. 

 

Key Research Outcome:  Stable isotope analyses of YCA workers, plants, herbivores and predators 

collected from four declining supercolonies in 2010‐2011 indicate that at supercolony densities, a 

substantial fraction of YCA dietary intake is plant‐derived.  This is consistent with the idea that YCA 

supercolonies depend heavily on honeydew derived from scale insects for a large fraction of colony 

food and energy requirements, and provides support for the idea that indirect control over YCA 

supercolonies could be achieved by targeting honeydew‐producing scale insects for biological control.  

 

   

13

Project 1c. Scale Insect Removal Experiment 

Although Projects 1a and 1b above will indicate the importance of honeydew in the diet of YCA 

and the relative contribution by scale insect type, large‐scale field experiments are needed to 

establish the influence of scale insects on population dynamics of the YCA.  This experiment uses 

the systemic insecticide imidacloprid to remove scale insects in YCA supercolonies and follows 

ant population dynamics.  

Research Findings 2009‐2013 

The original intention of the is experiment was to use the systemic insecticide imidacloprid to remove 

scale insects from an experimental plot, and to monitor ant activity before and after to determine the 

dependency of YCA at supercolony densities on scale insects.  This was essentially a proof‐of‐concept 

experiment for indirect biocontrol.  The intent was sow the treatment plot with tablets containing 

imidacloprid, which would be taken up by the root systems of trees and transmitted to scale insects, 

removing them from the canopy.  This would mimic the effect achieved through the introduction of a 

biological control agent for scale insects on the honeydew supply to YCA. 

The experiment was not carried out as planned.  Although imidacloprid is routinely used in single 

species Eucalyptus plantations to control herbivorous insect pests, it has not been used in natural 

forests where plant species diversity, and a range of size classes of trees from sapling to canopy giants, 

poses significant challenges for achieving consistent uptake of the toxin across all individual trees.  In 

addition, analyses of honeydew would have been mandatory to test the possibility that any decline in 

YCA density on the treatment plot was more likely due to scale insect death and a reduction in the 

honeydew supply, rather than a toxic effect due to the presence of imidacloprid or it metabolites in 

honeydew.  As pointed out above, collecting and preparing honeydew for analysis was challenging in 

itself.  Instead, we used a physical barrier applied to tree trunks to prevent YCA from accessing their 

honeydew supply in tree canopies.   

The experiment was a Before‐After‐Control‐Impact (BACI) design on two forest plots in a YCA 

supercolony abutting the Winifred Beach Track. There were two plots, each 40 m x 40 m, and one was 

designated as the control plot, the other as the treatment plot.  On the treatment plot, tree bands were 

made by winding Gladwrap™ around the boles of all trees >2 cm DBH. Bands blocked YCA traffic flow to 

and from the forest floor, resulting in “log jams” of downward moving ants, most replete with 

honeydew, above the bands (Fig. 4a). Throughout the experiment these stranded ants were returned to 

the forest floor by brushing them gently off each bole, so that any decline in YCA abundance on the 

ground could not be attributed to the retention of these ants on trees.  Repeated application of Mr 

Sheen™ spray‐on furniture polish to each band over the experiment greatly increased the effectiveness 

of the barriers.  No bands were applied to trees on the control plot. 

The measured response variables were YCA trunk traffic and YCA ground activity, both measured in the 

inner 20 x 20 m core of each plot.  YCA trunk traffic was estimated by counts per 30 s in a 10 x 10 cm 

quadrat on each of 10 trees, while ground activity was monitored using ant counts per 30 s on one 

quadrant on each of twelve 20 x 20 cm cards. (Fig. 5a).  Both variables were monitored at 3‐4 day 

intervals, 9 times before and after applying tree bands, during the dry season in 2012.  Results were 

analyzed as a one‐way repeated measures ANOVA, using ant exclusion from the forest canopy as the 

main factor and time as the repeated measures factor. In this design, the time x treatment interaction is 

the key term, with a significant treatment difference after, but not before treatment application.  

14

Bands effectively excluded YCA from the canopy, resulting in a precipitous decline and the virtual 

elimination of YCA traffic on tree boles 4 weeks after the tree bands were in place (Fig. 4b; Treatment x 

Time interaction, F1,32 = 90.198, P = 0.000).  YCA abundance on the ground fell and diverged markedly 

from the control plot two weeks after tree bands were placed (Fig. 5b; Treatment x Time interaction, 

F1,32 = 37.604, P = 0.000). YCA abundance declined ~3‐fold compared to average pre‐exclusion values, 

and was ~5‐fold lower than on the control plot 4 weeks. If card counts are converted to YCA densities 

(using the regression y = 15.694x – 21.612; Abbott 2005), YCA densities on the forest floor fell from ~400 

m‐2 before to ~140 m‐2 after exclusion from the canopy, and when the experiment was terminated were 

~600 m‐2 on the control plot compared to ~100 m

‐2 on the exclusion plot.  We attribute the decline in 

YCA density on the ground to their exclusion from honeydew resources from scale insects in the canopy.  

Two alternative explanations are not likely.  First, plot disturbance when setting up the tree bands on 

the treatment plot could have affected YCA activity on the ground but would be unlikely to explain the 

magnitude of change in YCA abundance after bands were in place.  Second, this experiment excluded 

YCA from all canopy resources, not just honeydew, and its possible that it was exclusion from other food 

sources, such as invertebrate prey, that caused the observed decline in density on the ground.  In 

anticipation of this, video records were made of samples of ants descending tree trunks to determine 

the proportion with distended shiny gasters (indicative of honeydew foraging), versus the percentage of 

workers carrying prey items.  These records are still being processed, but observations indicate most 

workers were foraging for honeydew, and < 1% were carrying prey. 

 

Key Research Outcome:  The exclusion of YCA from access to scale insects at a large experimental field 

site caused YCA activity on the ground to decline 5‐fold within 4 weeks, compared to pre‐treatment 

levels.  This large field experiment validates the key concept of indirect biological control for YCA on 

Christmas Island; exclusion of honeydew‐producing scale insects from YCA caused a significant and 

substantial reduction in YCA abundance on the ground. 

   

   

15

Project 1d. Carbohydrate supply and YCA growth and behaviour 

The importance of simple carbohydrates in the population growth and behaviour of the yellow 

crazy ant (YCA) will be assessed by varying carbohydrate supply to laboratory colonies and 

measuring brood production, worker survival, and aggression. 

Research Findings 2009‐2013 

This experiment consisted of nine treatments that varied the absolute amount, but not the 

concentration, of sugars available to YCA colonies.  Eighteen YCA nests were set up in plastic containers 

sitting in water traps to contain the ants.  Each nest initially contained 2 queens and 200 workers, and 

they had unlimited access to water and protein (thawed crickets) for the duration of the experiment.  

Two nests were assigned to each of nine sugar treatments, 0, 10, 20, 40, 80, 160, 320, 640, and 1280 µl, 

delivered as 13% honey water every 3‐4 days for two months.  In the last week, novel objects (a small 

frame of bamboo skewers) were added to track YCA exploratory behaviour, and behavioural assays 

against the big‐headed ant Pheidole megacephala were conducted to assess the impact of sugar supply 

on interspecific aggression of YCA.  In these aggression assays, three YCAs and three Pheidole were 

placed in a 6 cm diameter vial with fluon‐coated sides for 10 minutes. The time to the first spray of 

formic acid by each YCA, the total number of sprays by each YCA, and the total number of P. 

megacephala dead after 10 minutes was recorded.   

Performance and foraging behaviour of yellow crazy ants depend on sugar supply.  Per capita 

recruitment to sugar indicated that a smaller fraction of colony workers was needed to collect sugar 

with increasing sugar supply (Fig. 6a). Colony performance, as measured by production of workers and 

males (Fig. 6b) increased with sugar availability (P = 0.034) whereas per capita death rate decreased 

with increasing sugar availability (Fig. 6c). Per capita encounter rate of YCA with novel, non‐food objects 

placed in the nest, a measure of foraging tempo, also increased with sugar supply (Fig. 6d). 

Aggressive behaviours in the yellow crazy ant increased with sugar supply. YCA with access to more 

sugar sprayed P. megacephala with formic acid sooner and more often (Fig. 7a; P = 0.006), and killed 

more P. megacephala in 3:3 interaction trials (Fig. 7b). 

 

Key Research Outcome:  Dynamics and behaviour of YCA in laboratory colonies depended on 

carbohydrate supply.  When sugar supply was elevated, reproductive output by queens increased, 

death rates of workers decreased, foraging tempo quickened, and interspecific aggression intensified.  

These results suggest that sugar supply, through honeydew supplied from scale insects, plays an 

important role in YCA supercolony dynamics, foraging efficiency, and interspecific aggression. 

   

16

Research Project 2.  Scale insects and natural enemies 

For indirect biological control of the YCA to be feasible, appropriate natural enemies must be 

available.  The most likely source of specialist natural enemies is in association with the target 

scale insect in its area of origin.  Our co‐operator (Dr. R. Pemberton, USDA‐ARS Ft Lauderdale 

FL) is already well advanced in development of biological control of the lac scale Paratachardina 

sp. nov. and recently determined SEA as its area of origin.  Further, he agreed to search for and 

collect Tachardina aurantiaca in Thailand and Malaysia for us from which they have now reared 

several species of hymenopteran parasitoids that are currently being described.  Research 

outlined below is directed at building on these preliminary results to locate and evaluate 

potential biological control agents for T. aurantiaca in SEA, defining the scale insect fauna of 

Christmas Island, determining any natural enemies of scale insects already on Christmas Island, 

and establishing a pre‐release monitoring program for T. aurantiaca.   

 

Projects 2a and 2c. Natural enemies survey, parasitization rates of lac scale 

insects (Tachardina aurantiaca and Paratachardina pseudolobata) and 

parasitoid behaviour in area of origin (Southeast Asia) and on Christmas Island 

2a Collection of scale insect material to rear enemies and identification of candidate parasitoids 

for consideration in biological control.  Species descriptions, biology and behaviours of suitable 

candidates as biological control agents.  Separation of parasitoids into wanted primary 

parasitoids and undesirable hyperparasitoids. 

2c Identification of existing natural enemies (if any), and predation and parasitism rates on key 

scale insects on Christmas Island.  This will identify if significant natural enemies of scale insects 

are already present on the island. 

Research Findings 2009‐2013 

This part of the research very quickly focused on Tachardina aurantiaca as the key Kerriidae honeydew 

producer on Christmas Island.  Although Paratachardina pseudolobata produces honeydew, females 

flick droplets away from their bodies (Howard et al. 2010) making it unavailable to foraging YCA.  Below, 

we present information on the target T. aurantiaca including its geographic range in Southeast Asia, its 

life cycle, its natural enemies and incidence of parasitism in Southeast Asia and on Christmas Island, and 

a description of the biology of its candidate biological control agent, Tachardiaephagus somervillei.  We 

conclude this section with a short description of the suite of parasitoids of soft scales found on 

Christmas Island. 

Distribution of T. aurantiaca in Southeast Asia.  We located populations of T. aurantiaca across a 1900‐

km east‐west distribution in Sundaland, its putative area of origin (Fig. 8).  This region is the part of 

Southeast Asian continental shelf that was exposed during the last ice age, encompassing Peninsular 

Malaysia, Borneo, Java, and Sumatra).  Much of the search for T. aurantiaca in Malaysia was targeted, 

using a highly suitable and widespread host plant, Milletia pinnata, as a focus.  Search effort totalled 27 

days In Malaysian Borneo, and 5 days were spent searching in Singapore.  Live aggregates of yellow lac 

scale (yellow circles in Fig. 8) were located on Penang Island, and in Klang (Selangor) and Kepong 

17

(Selangor) in Peninsular Malaysia.  In Singapore, T. aurantiaca was found on the campus of the National 

University of Singapore.  In Sarawak, live aggregates were discovered around Santubong and Kuching 

(two sites ‐ Kampung Istana and Kampung Boyan). In Sabah, live aggregates were found in the Sandakan 

area and Sepilok.  Dead aggregates (not shown above) were found in Melaka, peninsular Malaysia and 

in Temon, 190 km south of Kota Kinabalu, Sabah.  Ants tended T. aurantiaca at all sites and collected 

honeydew (Penang – Crematogaster sp.; Klang – Oecophylla smaragdina; Kepong – Dolichoderus sp.; 

Kampung Istana – Anoplolepis gracilipes; Kampung Boyan – Oecophylla smaragdina; Singapore, 

Sandakan and Sepilok – Anoplolepis gracilipes).  

Assemblage of natural enemies of T. aurantiaca in Southeast Asia and on Christmas Island.  On 

Christmas Island, search focused on seven areas (see Figure 12) and examined over 11,000 females and 

2000 males of the yellow lac scale.  In Malaysia, targeted search for T. aurantiaca on known host plants 

(e.g., Milletia pinnata, Acacia mangium x A. auriculiformis) was frequently used to locate T. aurantiaca.  

Because the yellow lac scale is so rare across Malaysia, many fewer individuals were inspected for 

parasitization. To determine natural enemies, host plant twigs with aggregates of T. aurantiaca were 

first inspected, and then isolated so that emerging parasitoids could be collected for later identification. 

Female T. aurantiaca, either individually or in aggregates, were inspected for parasitoid exit holes to 

estimate parasitization rates. Individual females were also isolated to collect emergent parasitoids and 

dissected to determine overall rates of parasitization. 

The assemblage of natural enemies of T. aurantiaca is much more diverse in the area of origin that in its 

introduced range on Christmas Island (Table 1).  Using a combination of historical records (Noyes 2012) 

and direct field surveys, there are six primary parasitoids that use T. aurantiaca as a host in Malaysia, 

but only one on Christmas Island.  Furthermore, the one parasitoid on Christmas Island, Marietta 

leopardina, can only successfully attack males of T. aurantiaca.  Females of this species attempt to lay 

eggs inside females of Tachardina, but the test is seemingly too tough for the ovipositor to penetrate.  

In addition to parasitoids, two lepidopteran predators of female T. aurantiaca were also been found in 

both the native and introduced ranges, but on Christmas Island these are extremely rare.  Two 

hyperparasitoids, Promuscidea unfasciativentris and Aprostocetus purpureus, were isolated from T. 

aurantiaca in Malaysia, but not on Christmas Island (Table 1). 

Parasitism of T. aurantiaca in its native and introduced ranges.  In Southeast Asia, T. aurantiaca is rare 

and evidence of female parasitization was frequently seen in its native range in SE Asia (Fig. 9).  In 

contrast, in its introduced range on Christmas Island, T. aurantiaca is superabundant and there was no 

evidence of female parasitization (Table 2).  In Southeast Asia, the rate of parasitism was high, varying 

from a mean of 29% to 81% at different sites.  The rates in Table 2, based on the incidence of 

emergence holes, almost certainly underestimate actual parasitization rates because parasitized 

females from which parasitoids have not yet emerged would not be included. To investigate this, 

parasitisation rates of 5 additional aggregates in Sarawak were assessed by counting emergence holes, 

and then by dissecting the females to count unemerged parasitoid larvae.  Parasitization was estimated 

as 44.6 ± 9.6% (mean ± SE) by emergence holes, but as 61.4 ± 7.7% when females with unemerged 

larvae were added.  As a further example, a small aggregate near Kuching that showed no visible sign of 

parasitization (i.e. no exit holes) was found to be 100% parasitised after dissections.   

Tachardiaephagus somervillei parasitized T. aurantiaca across all sites examined (Fig. 9a).  

Superparasitism, where more than one progeny is produced per host individual, is frequent. The mean 

number of T. somervillei emerging from each parasitized female T. aurantiaca was 2.1 (range 1‐ 4, N = 

30) and up to 5 emergences occurred from each female at sites in Peninsular Malaysia.  Coccophagus 

18

tschirchii and C. euxanthodes were also isolated from T. aurantiaca (Table 1), but these species were 

uncommon and found only in Peninsular Malaysia (Fig. 9b). 

In contrast to the widespread parasitism of T. aurantiaca in Southeast Asia, parasitism of females was 

never observed on Christmas Island.  More than 11,000 females from multiple sites (Table 2) were 

collected and inspected under magnification over two years to determine the presence of any 

parasitoid emergence holes.  Single exit holes were observed in some male T. aurantiaca at a few sites. 

In the laboratory, the primary parasite Marietta leopardina emerged from these males. Parasitization 

rates were low, ranging from 0 ‐ 10% (N= 558, 751, and 696 males examined on three trees at Hugh’s 

Dale, Anderson’s Dale, and Sydney’s Dale), but M. leopardina is clearly not an effective biological control 

agent of female T. aurantiaca on the island. High densities of intact females occured where M. 

leopardina was present and, on Christmas Island, T. aurantiaca may be parthenogenetic (G. Neumann, 

unpublished results). 

Biology, ecology and life cycle of the parasitoid microhymenopteran wasp, Tachardiaepagus 

somervillei.  T. somervillei was first described by Mahdihassan in 1923 as Lissencytus somervilli but in 

1928 Ferriere transferred L. somervillei Mahdihassan to Tachardiaephagus and also later downgraded 

the species somervillei to a variety of T. tachardiae Howard (Hayat et al. 2010).  However, Hayat et al. 

(2010) regarded T. somervillei as a valid species. T. somervillei is known to occur in India, Thailand and 

Malaysia (Hayat et al. 2010 and references within).  During our exploration for natural enemies of 

Tachardina aurantiaca, T. somervillei was found and its identity was confirmed by Dr. Mohammad Hayat 

(Table 7) from sites in Selangor, West Malaysia and in southwestern Sarawak, East Malaysia.  We also 

observed this parasitoid in eastern Sabah, East Malaysia but its identity has not yet been confirmed.  

With its large geographical range (Fig. 8), T. somervillei is a very widespread and frequent natural enemy 

of T. aurantiaca. 

Host records for T. somervillei indicate that this parasitoid attacks four species in the genus Kerria 

(Noyes 2012) and T. aurantiaca (Table 3).  The host records sometimes do not specify the species of 

Tachardina parasitized but the only known species in the genus Tachardina within the recorded 

geographical range of T. somervillei is T. aurantiaca.  The apparently restricted host range of T. 

somervillei based on historical records is not surprising: all known parasitoids within the genus 

Tachardiaephagus have been recorded only from lac scales (Kerriidae), with the single exception of a 

coccid (Ceroplastes eucleae) recorded as a host of T. similis in Africa.  This latter host record, however, 

has been discounted by Prinsloo (1977).  While host ranges of the species in the genus 

Tachardiaephagus have not been assessed in detail, Sharma et al. (2006) mentions T. somervillei (along 

with T. tachardiae) as “exclusive to lac ecosystem”. 

Besides taxonomic work, very little research has been done on the biology of Tachardiaephagus spp. 

even though the species attacks economically important lac scales, such as Kerria lacca (Kerr) and are 

considered pests in lac‐producing regions (Sharma et al. 2006).  Our initial observations in peninsular 

Malaysia and Sarawak provide basic information on the life cycle and biology of T. somervillei in relation 

to T. aurantiaca.  The basic biology and life cycle is similar to that of other encyrtids that attack scale 

insects.  T. somervillei attacks mature female hosts, but never attacks males.  Parasitoid eggs are 

deposited inside the host’s test (the test is a secretion that covers the scale insect’s body), probably 

through the anal pore, and the hatching parasitoid larvae consume the host’s body inside the test.  The 

larva pupates after larval development is completed.  The adult wasp emerges from the pupa and 

through a round, smooth‐edged whole which it drills through the test and exits the dead host.  

Development time from oviposition to adult emergence can vary, but it is usually about 3 weeks. 

19

More than one parasitoid may emerge from a single host (superparasitism), and the number of 

emerging progeny is correlated with host size.  In order to investigate the relationship between the 

number of emerging parasitoid progeny and the size of the female T. aurantiaca host in field conditions 

(Kuching, Sarawak), a random sample of 50, parasitized female T. aurantiaca were measured (greatest 

horizontal diameter of test) and the emerging adult parasitoids were counted from each host.  There 

was a significant positive correlation between host size and parasitoid progeny produced (R2 = 0.47, p < 

0.001) (Fig. 11).  This relationship is probably best explained by the simple fact that larger hosts provide 

more food resources for more parasitoid larvae to complete development.  It is not clear whether this 

superparasitism is self‐superparasitism (a single female parasitoid ovipositing multiple eggs in a single 

host) or if it is superparasitism in terms of intraspecific competition (different individual parasitoids 

ovipositing in the same single host).  This positive relationship between host size and production of T. 

somervillei progeny will be important in captive rearing, release site selection, and ensuring 

establishment during inoculative releases. 

The longevity of adult parasitoids and their fecundity can vary greatly depending on diet and the source 

of nutrients such as sugar from honeydew or nectar (Lee et al. 2004).  It is possible that T. somervillei 

feeds on honeydew secreted by its host.  Further, some parasitoids stab their hosts with their ovipositor 

but do not lay eggs, instead feeding on the hemolymph that leaks out.  Such "host feeding" can also be 

very important in longevity and fecundity (Wheeler 1996).  Host feeding, although not yet observed in 

the field, would be advantageous because it can result in the death of the host without it being 

parasitized. 

Natural enemies of soft scales on Christmas Island.  Parasitization of soft scale insects (Coccidae) on 

Christmas Island was very rare during the searches between 2010 and 2012.  Signs of parasitoid 

presence were initially found only in the settled area in the northeast of the Island.  The reason for the 

apparently limited distribution of soft scale parasitoids on Christmas Island is not clear.  The 2010 dry 

season was unusually wet and scale insect populations were very low in general throughout the island.  

It is possible that parasitoid populations went locally extinct in areas outside of the settled areas and the 

recolonization of soft scale aggregates simply did not occur at detectable levels in 2011 and 2012.  

Alternatively, despite their presence in the settled areas, these parasitoids are naturally absent from 

large parts of the rainforest on Christmas Island due to dispersal limitation. 

Parasitization was observed in Coccus sp. and Pulvinaria urbicola, a newly recorded invasive soft scale 

on the island (Neumann et al. 2011).  Two parasitoids, Coccophagus ceroplastae (Aphelinidae) and Encyrtus infelix (Encyrtidae) were recovered from Coccus sp., both first recorded in the settled areas.  

Additionally, two Metaphycus spp. (Encyrtidae) and Coccophagus nr. bivittatus (tentatively 

identification) were recovered from immature soft scales (most likely P. urbicola) near the 'Boulder' 

(South Point) on the host plant Pisonia grandis. 

Coccophagus ceroplastae and E. infelix are both known to attack a variety of soft scale species, including 

three that are important in YCA supercolonies (Table 4: Coccus hesperidium, Saissetia oleae, S. coffeae).  

It is possible that these two parasitoid species could be used to control all, or almost all, soft scales at 

acceptable levels on Christmas Island.  For example, C. ceroplastae can control the damaging scale 

insect P. urbicola under laboratory conditions.  Potted Pisonia umbellifera plants were infested with P. 

urbicola and the scale insects were allowed to reproduce.  When the scale insects of the first generation 

were estimated to be in the second instar of their development, 60 field‐collected C. coccophagus were 

liberated on the plants in two batches one week apart.  Parasitism was observed approximately three 

weeks later.  Parasitization rates were low and not quantified, but the suitability of the host was 

20

demonstrated.  Approximately 11 weeks after the first parasitoid introduction, two of the host plants 

had no remaining live scale insects.  The other two plants died before the eradication of the scale insect 

infestation but parasitism rates were high (G. Neumann, unpublished data).  The potential of C. nr. 

bivittatus and the two Metaphycus species is not clear.  Study of the potential of these parasitoids will 

commence in Phase 2 of the biological control project as well as the mass rearing, redistribution, and 

impact survey of the identified soft scale parasitoids, C. ceroplastae and E. infelix. 

 

Key Research Outcomes:  Few natural enemies of the key honeydew‐producing scale insect Tachardina 

aurantiaca occur on Christmas Island, and they do not regulate its population size. No parasitoids of 

female T. aurantiaca were found. Conversely, within its native range in Malaysia, T. aurantiaca is rare 

and patchily distributed, associated with diverse natural enemies, including at least five species of 

primary parasitoids, and it suffers high parasitization rates – all attributes consistent with population 

regulation by natural enemies.  Importantly, high parasitism rates in Malaysia occurred in the presence 

of honeydew‐collecting ants, including the yellow crazy ant.  Of the primary parasitoids known to attack 

yellow lac scale from our studies in Malaysia, Tachardiaephagus somervillei (Encyrtidae) is the most 

promising agent for introduction and release on Christmas Island.  All Tachardiaephagus species have a 

narrow host range and appear to be family specialists, known only to attack the Kerriidae, the family to 

which the yellow lac scale belongs (Table 3).  Our initial studies indicate that (a) T. somervillei attacks T. 

aurantiaca across 1900‐km range in Peninsular Malaysia and Malaysian Borneo, (b) is the most 

abundant natural enemy of T. aurantiaca, (c) has a short life cycle compared to its host, (d) exhibits 

superparasitism (i.e., where multiple progeny emergence from a single host individual); (e) causes high 

rates of parasitism on T. aurantiaca in the presence of tending ants, including the yellow crazy ant, and 

(f) can be reared under laboratory conditions.  Coccophagus ceroplastae and Encyrtus infelix, both 

parasitoids of a wide variety of coccid scale insects, are already present on Christmas Island. The three 

parasitoids T. somervillei, C. ceroplastae and E. infelix could be deployed in combination against the 

entire assemblage of honeydew‐producing scale insects in YCA supercolonies.

 

   

21

Project 2b. Scale insect survey on Christmas Island (biology, host range, 

habitats, natural history, identification) 

Comprehensive knowledge of the scale insect species present in rainforest and the built 

environment on Christmas Island.  This information will indicate habitats and host plants of T. 

aurantiaca and other scale insects on Christmas Island.  It will provide information on nativeness 

of the scale insect fauna which will aid determination of a host specificity test list, testing 

protocols, and other regulatory matters for biological control agents.   

Research Findings 2009‐2013 

Extensive searches for scale insects were carried out over three years 2010‐2013, using five methods.  

First, surveys were conducted using Timed Searches, in which 30 min was spent looking within a 50‐m 

radius at each of 151 waypoints from the CINP island‐wide survey (Fig. 12).  Searches were replicated 

three times in each dry season in 2010‐2012.  Second, searches were conducted along the entire length 

of five tracks, a total of 21 km, twice in each of the dry seasons of 2011 and 2012 (Northwest Point 

Track, 4.7 km; Boulder Track, 6 km; Blowholes Road, 3.4 km; Martin Point Lookout to CINP boundary, 

1.9 km; and, Dolly Beach Boardwalk, 1.8 km). Search effort totalled ~405 hours that did not include 

travel between sites.  Third, endemic plant species were a focal point of further search assuming that 

endemic scale insects would be more likely to be associated with them (Neumann et al. 2007).  Fifteen 

of the 18 species of endemic plant species were located and examined between 2010‐2012. Ten rare 

and endemic plants species from the CINP database were searched for scale insects at 125 locations. For 

each common endemic plant species, 30 haphazardly selected individuals were examined each year 

between 2010‐2012.  Fourth, opportunistic searches were made of exotic plants at many locations 

around the settled areas in the ‘Dog’s Head’ area of the island.  Fifth, CINP personnel also aided the 

search by being aware of scale insects during the island‐wide survey in 2011.  

Twenty‐one species of scale insects in six families have been found on Christmas Island (Table 4).  It is 

highly probable that these species, all with broad host plant ranges and geographic distributions, were 

introduced following human settlement on Christmas Island and are non‐native. No endemic scale insects 

were found. 

 

Key Research Outcomes:  No native or endemic scale insect species have been discovered in intensive 

and extensive searches for scale insect species on Christmas Island.  However, 400 hours of search over 

two years did yield five additional exotic scale insect species previously unknown to the island.  

Assuming that any prospective biological control agent for Tachardina aurantiaca on Christmas Island 

would be a narrow family specialist (Kerriidae) and all known scale insect species are non‐native and 

invasive, the probability of any direct non‐target effects is negligible. 

 

   

22

Project 2d. Genetic and morphological matching between Tachardina 

aurantiaca and Paratachardina pseudolobata on Christmas Island and 

Southeast Asia. 

Determination of species identity and likely area of origin of T. aurantiaca and P. pseudolobata.  

This is critical for further targeted search for biocontrol candidates.  Specimens from Christmas 

Island and Southeast Asia (Indonesia, Thailand, West Malaysia, and East Malaysia) will be 

compared genetically and morphologically. 

Research Findings 2009‐2013 

T. aurantiaca collected from 5 different sites and host plant species across Christmas Island are 

morphologically and genetically identical, based on cuticular morphology and mitochondrial cytochrome 

c oxidase subunit 1 (COI) and 28S ribosomal RNA sequences (P. Gullan and L. Cook, personal 

communications, 2012). Initial morphological and genetic studies of T. aurantiaca collected from sites in 

Sarawak indicate that they are morphologically and genetically identical to T. aurantiaca on Christmas 

Island (P. Gullan, personal communication, 2012). 

Further study of Paratachardina pseudolobata was not pursued because, as pointed out above, it is not 

a source of useable honeydew for YCA on Christmas Island. 

 

Key Research Outcome:  The single population of T. aurantiaca on Christmas Island matches 

morphologically and genetically those populations examined so far within its native region in Southeast 

Asia.  This establishes the identity of Tachardina aurantiaca on Christmas Island, making the successful 

establishment on Christmas Island of a biological control agent that attacks T. aurantiaca in its native 

range more likely.  Further collections and analyses of T. aurantiaca in Eastern Malaysia (Sabah) and 

exploration in southern Thailand should establish if any morphological or genetic variation occurs across 

its native distribution in Southeast Asia. 

 

 

   

23

Project 2e. Scale population dynamics, especially the ecology of lac scale, 

Tachardina aurantiaca 

Pre‐release monitoring of T. aurantiaca and P. pseudolobata prior to any introduction and 

release of natural enemies so that the efficacy of natural enemies in controlling scale insect 

numbers and reducing yellow crazy ant densities can be determined. 

Research Findings 2009‐2013 

The life cycle of Tachardina aurantiaca is relatively long, with one complete generation from F1 crawler 

settlement, through female maturation, to F2 crawler production and settlement completed between 

88 ‐ 100 days, depending on host plant species (Table 5).  Males emerge about 6 weeks after crawler 

settlement, consistent across host plant species (Table 5).  On Christmas Island, there are overlapping 

generations such that all stages, including crawlers, female nymphs, and mature females can all be 

found together on twigs and along the midribs of leaves.  This suggests that suitable life stages of T. 

aurantiaca susceptible to attack by Tachardiaephagus somervillei are available most of each year. 

Female size and offspring production vary considerably and is significantly correlated at the time of 

crawler release both in field and laboratory populations (R2 = 0.295, p < 0.001 in the laboratory and R2 = 

0.207, p = 0.006 in the field) (Fig. 13).  Large females can produce over 600 crawlers, indicating that 

conditions that affect female growth before crawler production could have a very strong effect on 

population growth. Conditions affecting grown are not well understood but could relate to settlement 

density of crawlers, position of crawler settlement on the host, host plant identity, and time of year. 

The role of males in reproduction is not clear, because it appears that some females are capable of 

producing offspring parthenogenetically (Ong and Neumann, unpublished data).  The approximately 6‐

week development time of males suggests that females are mature at that time. Females apparently 

continue to live and grow well beyond the completion of development and offspring production occurs 

long after the female becomes mature (mating might not occur at all).  Further experiments are under 

way to clarify the role of males in reproduction and the effect (if any) of parthenogenetic reproduction 

on life span and fecundity of T. aurantiaca. 

 

Key Research Outcomes:  The life cycle of Tachardina aurantiaca is relatively long for a scale insect but 

several overlapping generations occur in a single year.  Female size is significantly correlated with 

fecundity, indicating that conditions that affect female size are likely to have a strong influence on 

population growth rates and density.  The role of males in reproduction is not yet clear although it 

appears that some females can reproduce parthenogenetically. All of these attributes will influence 

host‐parasitoid dynamics on Christmas Island.  

   

24

Research Project 3.  Strategic planning for biocontrol introduction  

Australia is well advanced in the regulation of import and release of exotic invertebrate 

biological control agents. Legislation stipulates import conditions, risk assessment, host‐

specificity test lists, release protocols, and pre‐release studies prior to approval of biological 

control introductions.  Consultation with regulators early in the project is essential in the 

planning, conduct, and evaluation of research.  Furthermore, early identification and agreement 

with co‐operators is essential for completion of research components key to proof of concept of 

indirect biological control of the YCA. Consultation outlined below will put project planning 

within the regulatory frameworks for biological control introductions in Australia and determine 

key co‐operators necessary to advance the project.  

Project 3a.  Planning research in step with legislative and regulatory 

requirements for biological control introductions 

Smooth preparation and transparency in planning for introduction of biological control agents.  

Coordination of research findings in step with regulations (i.e. DAFF, DSEWPaC).  Written report 

anticipating the regulatory steps and hurdles for advancement of the project.   

Research Findings 2009‐2013 

The importation and release of an exotic biological control agent (BCA) on Christmas Island, an external 

territory of Australia, is regulated under Australian Government legislation by two independent, but 

parallel frameworks.  The first framework falls under the Quarantine Act 1908, and subordinate 

legislation in the Quarantine (Christmas Island) Proclamation 2004.  The process to seek approval to 

import and release an exotic biological control agent on Christmas Island is outlined by Biosecurity DAFF 

(Department of Agriculture, Fisheries and Forestry) in a document entitled Revised Biosecurity 

Guidelines for the introduction of exotic biological control agents for the control of weeds and plant 

pests   

(http://www.daff.gov.au/ba/reviews/biological_control_agents/protocol_for_biological_control_agents

/guidelines‐introduction‐exotic‐bcas‐weed‐and‐plants 

Second, because the proposed action could have a significant impact on the environment, an 

Environmental Referral is required under legislation in the EPBC Act (1999).   This framework is outlined 

by the Department of Sustainability, Environment, Water, Populations and Communities at  

http://www.environment.gov.au/epbc/assessments/index.html 

The criteria for evaluating importation and release of a BCA under the two frameworks differ 

somewhat.  Under the Biosecurity DAFF framework, import risk analysis for a BCA differs from a 

standard commodity import analysis that assesses the probability of entry, establishment and spread. 

Because BCAs intended for release are deliberately introduced, risk analysis focuses on off‐target effects 

alone. Under the EPBC Act, DSEWPaC also has a linked approval process for the import and release of 

BCAs which uses the final risk analysis report produced by Biosecurity DAFF. This may be used by the 

DSEWPaC minister to include the BCA on the live import list.   

Under separate legislation under the EPBC Act, a proposed action is referred if it is likely to have a 

significant impact on a matter of national environmental significance (e.g. wetlands of international 

25

significance, threatened species and ecological communities, migratory species). The process for 

submission and evaluation of an Environmental Referral is given at  

http://www.environment.gov.au/epbc/assessments/pubs/flow‐chart.pdf 

Harmonization of these two frameworks is critical as we move through these regulatory processes.  Key 

issues and Australian government contacts for progressing issues in each framework are given in Table 

6. In discussions with Biosecurity DAFF, it was clear that they were unfamiliar with the Environmental 

Referral process (EACD) in DSEWPaC.  It was equally clear that the Environmental Assessment and 

Compliance Division in DSEWPaC had not previously encountered Environmental Referrals that 

addressed importation and release of BCAs. A search of the 100 most recent environmental referrals 

indicated that 42% related to mineral or energy projects, 31% to infrastructure development, 20% to 

residential development, 5% to biodiversity management, and 2% to other.  None of the Environmental 

Referrals since July 2000 on the referrals list page  

(http://www.environment.gov.au/cgi‐

bin/epbc/epbc_ap.pl?name=current_referrals&limit=999999&text_search=) 

addressed importation and release of a BCA.  However, Biosecurity DAFF and the EACD DSEWPaC are 

now exchanging information on the CI project.  

 

Key Research Outcomes:  Two regulatory frameworks govern the importation and release of an exotic 

biological control agent on Christmas Island.  To gain approval to import and release a biological control 

agent on Christmas Island, we will need to prepare and submit two sets of documents:  an Approvals 

Package under the DAFF protocol and an Environmental Referral to EACD, DSEWPaC.  The key 

government contacts involved in the two frameworks are described and currently consulting each 

other. 

 

   

26

Project 3b.  Identification and agreement with co‐operators 

Identification of key co‐operators and agreements to advance the project.  Cooperation will be 

necessary between Australian universities (e.g., project coordination, research staff mentoring 

and supervision); Australian federal agencies (e.g., assistance with regulatory issues in 

biocontrol introductions; taxonomic expertise on scale insects, ants, and parasitoids; Overseas 

universities (e.g., morphological and genetic studies of scale insects); Overseas government 

agencies (e.g., linked biocontrol program with foreign exploration and testing of natural 

enemies, biocontrol regulatory expertise ‐ USDA‐ARS, Invasive Plant Research Laboratory, FL; 

offshore facilities for safe host specificity testing – e.g., Malaysian Department of Agriculture) 

Research Findings 2009‐2013 

We have established relationships with many researchers in Australia, India, Malaysia, Singapore and 

the United States, all of whom bring different expertise and capacity to this project (Table 7).  Prof. 

Gullan and Dr. Cook provide taxonomic expertise on scale insects as well as morphological and genetic 

analyses for Tachardina aurantiaca on Christmas Island and in Southeast Asia.  Dr. Hayat provides 

taxonomic expertise in the identification of encyrtid and aphelinid parasitoids associated with T. 

aurantiaca.  A cooperative research agreement with Forestry Research Institute Malaysia provides 

benchspace and facilities for rearing T. aurantiaca and its natural enemies in Kepong, Selangor, 

Peninsular Malaysia.  Ms Ong, a Masters student under supervision of Dr. Neumann, is conducting her 

research on the biology of T. aurantiaca and developing rearing techniques for it and one of its 

important natural enemies, Tachardiaephagus somervillei.  Sarawak Forestry and the National 

University of Singapore provide laboratory space and field assistance.  Dr. Pemberton, who has worked 

on the biological control of the invasive lobate lac scale in Florida, provides advice and was instrumental 

in establishing some of the cooperators listed in Table 7.  

The complex permitting system in Malaysia has been negotiated successfully and permits to conduct 

research and collect specimens in West Malaysia, Sarawak, and Sabah have been granted.  

An ad hoc advisory group of expert biocontrol practitioners has been assembled to review and advise on 

development of a host test list and a host‐specificity testing protocol (Table 8).  Expertise in this group 

covers key aspects of in the development of biocontrol relevant to Christmas Island (e.g safety and risk 

assessment in biological control, host specificity of parasitoid natural enemies, biocontrol in natural 

areas, foreign exploration, scale insects as targets in biological control).  

 

Key Research Outcomes:  Collaborations have been established with researchers with expertise in the 

systematics, biology, and molecular genetics of scale insects, taxonomy of microhymenopteran 

parasitoids, and biological control of scale insects.  Cooperative agreements have been established with 

FRIM and Sarawak Forestry that provide benchspace and technical assistance.  Dr Neumann is serving as 

an advisor of a Masters student (Universiti Sain, Penang) who is conducting research on this project at 

FRIM. Research and collecting permits have been obtained from the States of Sarawak and Sabah, as 

well as a national collecting permit.   

 

   

27

Project 3c.  Safety and sanitary protocols anticipating a pre‐release 

environmental assessment of introduction 

An agreed list and protocol for host specificity testing of candidate bio‐control agents and 

protocols to eliminate and prevent the accidental introduction of hyperparasitoids to the island. 

Research Findings 2009‐2013 

To focus host‐specificity testing for Tachardiaephagus somervillei (Hymenoptera: Encyrtidae), a 

candidate biological control agent for the invasive introduced yellow lac scale (Tachardina aurantiaca)

(Hemiptera: Kerriidae), we used four approaches to assess the risk of importation and release of the 

candidate biological control agent T. somervillei to Christmas Island.  Risk was defined as off‐target 

impacts, including those that could affect endemic species or threatened and endangered species. 

These risk evaluations were based on host records of Tachardiaephagus from the scientific literature, 

the diversity and attributes of other scale insects (superfamily Coccoidea) on the island, the occurrence 

of endemic hemipterans known from Christmas Island, and the host ranges of encyrtid parasitoids 

known to attack scale insects.  All lines of evidence indicate that there is a very low likelihood that 

importation and release of T. somervillei would harm species of concern (i.e. those that occur on 

Christmas Island).   

We then describe a protocol for host‐specificity testing recommending that it be conducted within the 

area of origin (Malaysia) of Tachardina aurantiaca.  Identification of an agreed host test list and protocol 

for host range testing of a candidate biological control agent are necessary requisites under the 

Biosecurity DAFF guidelines for the approval of importation of exotic biological control agents for the 

control of weeds and plant pests (see Project 3a). Lastly, in their native range, many primary parasitoids 

have their own insect natural enemies, including those known as hyperparasitoids (i.e. parasites of 

parasites).  This is so for T. somervillei (Project 2a, Table 1).  We describe standard rearing and sanitary 

techniques to ensure that the founding population from Malaysia is free of hyperparasitoids before 

importation to Christmas Island  

Known host range of Tachardiaephagus somervillei.  We evaluated known host species records for all 

species of Tachardiaephagus using the Universal Chalcidoid Database (Noyes 2012) so that host range 

could be estimated and risk of release of T. somervillei assessed for species of concern on Christmas 

Island (see Sands and Van Driesche 2004).  The Universal Chalcidoidea Databases (Noyes 2012) is the 

most comprehensive database for chalcidoid parasitoids, with over 120,000 host/associate records 

(including associations with food plants of the hosts) and > 140,000 distribution records of the 

parasitoids in the superfamily Chalcidoidea.  It is very well developed, regularly updated and extremely 

well referenced.  Nevertheless, large databases can contain errors affecting reliability, such as 

erroneous published host records and outdated parasitoid taxonomy (Kuhlmann et al. 2006).  The most 

important source of error in this database is actual published erroneous records.  Since all records are 

referenced, doubtful records can be investigated and if necessary, filtered out.  

Seven described species of Tachardiaephagus are distributed in Southeast and South Asia, and sub‐

Saharan Africa (Noyes 2012). Host records of Tachardiaephagus are restricted to species within three 

genera (Kerria, Tachardina, and Paratachardina) of lac insects (Kerriidae)  (Project 2a, Table 3). 

Furthermore, all host species records for Tachardiaephagus somervillei are within two genera:  Kerria, 

comprising the lac insects of commerce, and Tachardina. These records suggest that Tachardiaephagus 

somervillei is highly likely to have a narrow host range restricted to kerriid host species. 

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28

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29

encyrtid species that share (as hosts) both coccoid species (scale insects) and any family represented by 

endemic species on Christmas Island could be found. 

There are no known records in the Encyrtidae of any parasitoid species that attacks both scale insects 

(Coccoidea) and host species in hemipteran families that have endemic representatives on Christmas 

Island (Table 9).  All known encyrtid primary parasitoids known to attack species in families which have 

endemic representatives on Christmas Island have primary hosts only within suborder 

Auchenorrhyncha.  While species in these hemipteran families are attacked by many species of 

chalcidoid parasitoids, many fewer or no encyrtid species are known to use them as hosts, and not one 

encyrtid species is reported with a host range so extremely broad that it encompasses both scale insects 

and any of these hemipteran families.  

Host specificity testing protocol.  Actual records for host range of Tachardiaephagus and known 

patterns of parasitism in the Encyrtidae indicate that it is highly improbable that T. somervillei would 

exhibit an extremely broad host range (one that would be unprecedented in any single species of 

Encyrtidae known to attack scale insects) and utilize any of the endemic hemipteran species on 

Christmas Island.  Thus, when the host specificity testing of the biological control agent is initiated using 

the centrifugal phylogenetic approach, the outer boundaries of the sequential testing should be set 

initially at a significantly closer distance from the target organism than the taxa represented on 

Christmas Island by endemics.  

A ‘test species’ is an insect species that is tested as a potential non‐target insect.  Since no non‐target 

scale insects were identified on Christmas Island, the list of test species will be determined using the 

centrifugal approach (Kuhlmann et al. 2006, Neumann et al. 2010).  In this approach, species other than 

the known target host of the biological control agent are tested with the most closely related species 

(least phylogenetic distance, and with close similarities in biology and ecology) tested first then less 

similar species thereafter (“centrifugal principle” ‐ Wapshere 1974). 

A test species will be considered a ‘suitable host’ if parasitoid emergence is observed during any of the 

exposure tests.  To be a suitable host, the parasitoid must (a) accept the test species when exposed, (b) 

must oviposit, (c) the eggs must hatch into larvae, (d) the larvae must complete development using the 

test species as the resource, (e) the larvae must pupate and, finally, (f) the emerging adult parasitoid 

must be able to exit (emerge from) the test species.  If parasitoid emergence from a test species is 

observed, the test species will be considered a suitable host without assessing the viability, fecundity, 

sex ratio and other characteristics of the emerging parasitoid generation. 

A test species will be considered ‘susceptible’ if the parasitoid causes significant mortality due to 

probing, host feeding (when the parasitoid stabs the insect with its ovipositor and then feeds on the 

insect’s hemolymph), oviposition, or oviposition and larval development.  Note that even if some 

mortality is observed due to the above, the test species will only be considered susceptible if the 

mortality resulting to the exposure to the parasitoid is significantly higher than in control groups 

(negative controls) of the test species where the test individuals are not exposed to the parasitoid. 

The ‘parasitoid’ in this case is T. somervillei (Hymenoptera: Encyrtidae), a widespread parasitoid native 

to Southeast Asia.  T. somervillei is an important parasitoid of Tachardina aurantiaca (Project 2a, Table 

1; Project 2c, Table 2). It is known to parasitize some scale insects in the family Kerriidae (lac scales) 

including the ‘target host’, Tachardina aurantiaca (Table 3). 

Selecting test species.  Host specificity testing can be a long and difficult process, depending on how 

problematic it is to establish and manage colonies of the parasitoid, the target host, the host plant of 

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the target host, and the test species.  Furthermore, resources and time are not unlimited and permitting 

issues to collect insects and run field experiments (when needed) in Malaysia can add to the time 

required to complete host testing.  Therefore, a manageable number of species should be used (10 to 

15, but fewer are acceptable if high specificity is found initially).  The species used will be largely 

determined by availability, so determining the actual test species at species or genus level is not 

possible at this point.  We can, however, predict to some degree the families of the test species that will 

be selected.  We will focus on neococcid taxa including the Kerriidae, the family to which the target host 

belongs (see Fig. 14, also Gullan and Cook 2007, Ross et al. 2012).  Considering the phylogenetic 

relationships of scale insect families (Fig. 14), we will aim to test one species in the Kerriidae, 

Paratachardina pseudolobata, which is also invasive on Christmas Island (see Project 2b, Table 4), and 

more than one species from the Coccidae.  Species in the Diaspididae will also be considered as a less 

closely related group of scale insects.  Early in the host testing process, an ‘out‐group’ (test species 

phylogenetically more distant) will also be used, most likely selected from the Pseudococcidae (Fig. 14).  

As mentioned above, availability will determine species selection to some degree but in some of the 

groups (e.g. Coccidae) there may be a number of species available.  Species that can be reared in 

laboratory conditions would be preferred but carrying out tests in field conditions should also be 

acceptable as long as the tests can be well controlled. 

No‐choice tests.  In no‐choice tests, only the non‐target test species will be provided to the parasitoid in 

the experimental replicates.  This is the most stringent test method that places the parasitoid under 

high “oviposition pressure”. 

For each test species, trials will be replicated 10 times.  Each replicate will consist of 1) one 

experimental cage with the test species (50 individuals in three different age groups/instars; 150 

individuals in total) exposed to 10 female and 10 male parasitoids, 2) one positive control cage 

consisting of 50 mature female T. aurantiaca exposed to 5 female and 5 male parasitoids in order to 

confirm that the parasitoids used in the experiment are of good quality and capable of parasitism in the 

given exposure time, and 3) one negative control cage which will be similar to the experimental cage 

except the test species will not be exposed to parasitoids.  The negative controls will be used to 

determine any effect of parasitoid exposure on insect mortality other than successful parasitization 

such as probing, host feeding and oviposition without successful parasitoid development. 

The cages will consist of fine mesh bags (sleeves) fixed on the branches of plants that serve as host 

plants for the scale insects.  Parasitoids will be collected from a lab colony and introduced to the cages < 

24 h after emergence.  Exposure time to parasitoids will be determined during preliminary studies to 

determine the optimal time frame for mating, egg maturation and oviposition by the parasitoid. 

Evaluation: 

1) If the positive control does not yield any parasitoid emergence, the replicate will not be evaluated 

(failed replicate). 

2) If the positive control yields parasitoid emergence the replicate will be evaluated.  The parasitization 

rate in the positive will be noted but will not be compared to parasitization rates in the test replicate. 

3) Parasitoid emergence in the test replicate will be noted along with the approximate age and 

developmental stage of the individuals yielding parasitoid emergence.  These individuals will not be 

used to compare mortality rates due to reasons other than successful parasitism. 

4) Mortality of test species in test replicates and negative controls will be noted. 

 

31

Analysis: 

1) If any test replicates yielded any number of parasitoid emergences, the test species will be 

considered a suitable host.  The level of suitability of the test species will not be compared to the 

suitability of the target host at this stage of the project. 

2) Mortality (except mortality due to successful parasitism) rates of test insects and insects in the 

negative control will be compared using 2‐sample t‐tests.  If the mortality rate is significantly higher 

(α = 0.05), the test species will be considered susceptible and the reasons for mortality will be 

investigated.  

If a test species is susceptible (but not suitable), behavioural observations will be made to determine 

the cause of the effect of parasitoid exposure.  The observational arena will be a ‘window box’ arena.  

This arena is constructed by constructing a 10 cm W x 10 cm L x 5 cm H box with one side being glass.  

The box is constructed so that it can be placed on the stem of a potted host plant on which the test 

insects feed.  Female parasitoids are then liberated inside the box and the box closed.  The potted plant 

then can be placed flat on its side and the box positioned under a dissecting microscope.  Video footage 

is then captured using a high definition video camera with a microscope adaptor.  The footage (4‐6 h per 

observation) can be analyzed later for the cause(s) of mortality (i.e. probing, host feeding, or oviposition 

without full parasitoid development).  If oviposition is suspected, dissections will also be made to 

investigate parasitoid larval development. 

Other testing methods.  We considered using choice tests (where the parasitoid is presented with the 

test species and the target host simultaneously) and sequential no‐choice tests (where the parasitoid is 

presented with the target host first then it is transferred on to the test species).  However, in our case 

these tests may have limited value for reasons given below.   

A choice test would show whether a test species that is a suitable host in no‐choice tests would be 

consistently attacked when the target host is also available.  A physiologically suitable host may not be 

preferred over the target host and the assumption could be made that parasitization would not occur 

(or at very low level) in field conditions.  This test would be used in cases where the suitable host (found 

suitable in a no‐choice test) is of concern, e.g. a beneficial or endemic non‐target species that coexists 

with the target host.  However, this situation does not arise on Christmas Island where all known scale 

insects are non‐native and none of them are beneficial.  This test is further limited by the assumption 

that the test species and the target host occupy the same space hence providing the parasitoid with a 

choice. This would also not be the case on Christmas Island. 

A sequential no‐choice test would further show the unsuitability of a test species.  The parasitoid may 

be ‘motivated’ to attack the test species even if it did not attack it in a simple no‐choice test if the 

parasitoid is first allowed to initiate oviposition behaviour and to gain experience.  This test may be even 

more stringent than the simple no‐choice test and one would consider using it in the case of a test 

species that is of great concern to further show the unsuitability of the test species.  This would again 

require a beneficial or endemic non‐target species neither of which exists on Christmas Island.  

Furthermore, similar to the choice test, this would assume either the coexistence or very close 

proximity of the test species and the target host. 

Options for the location for host‐specificity testing.  There are three options for the location where 

host specificity testing could be conducted: 1) in quarantine containment at the release location 

(Christmas Island); 2) in quarantine containment on mainland Australia; and 3) in the native 

geographical range of the biological control agent where no containment would be necessary.  

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Option 1.  Testing in containment at the release location (Christmas Island).  This option is the least 

attractive and involves increased risks and expenses.  There is no quarantine containment facility on 

Christmas Island, a remote oceanic island.  The expense of constructing such a facility to Quarantine 

Approved Premises Criteria (Quarantine Insectary Level 2) for host‐specificity testing of a single agent 

would be prohibitive. Even if there were such a facility, in case of escape, the biological control agent 

would find an environment very similar to its native range with its natural host T. aurantiaca in 

abundance.  The benefits of this option would include easy access to the natural host for the parasitoid 

colony and no further travel if and when a release permit is obtained. 

Option 2. Testing in containment on mainland Australia.  While this option is more attractive than 

Option 1 above, it is still somewhat risky, and labour and cost intensive. It brings few benefits. The 

biological control agent (parasitoid) would have to be brought into containment along with its natural 

host (Tachardina aurantiaca).  This would pose the risk of not only a parasitoid escaping but also a 

potentially invasive, host‐generalist scale insect (on Christmas Island, for example, at least 15 

horticultural species are attacked by T. aurantiaca, including three species of Citrus, Macadamia, Guava, 

Pomegranate, Chili, Eggplant, Star fruit, and Soursop)(R.W. Pemberton and D.J. O’Dowd, unpublished 

results).  Using a containment facility in the temperate region of Australia could decrease these risks.  In 

case of quality control issues of the biological control agent due to ‘lab selection,’ additional travel, 

collection, and importation of the biological control agent would be necessary, further increasing costs.  

Natural host colony loss (which can easily happen due to overexposure to the parasitoid agent, fungal 

infections, etc.) would necessitate multiple importations of the natural host, which would once again 

significantly increase costs and risk. 

Option 3.  Testing in the native geographical range of the biological control agent with no containment 

necessary.  In our case, this option is the most attractive, most cost‐effective, and least risky.  There are 

many benefits to study biological control agents and carry out host specificity studies in the native 

geographical range of the agent.  In our case, both the parasitoid and its natural host is readily available 

from the wild in Malaysia which ensures good quality parasitoid and host cultures.  The risk factor 

would be zero as there would be no importation of any organisms.  Although obviously desirable, such 

studies in the native range are not common, in part because of the lack of local research facilities, lack 

of skilled and reliable cooperators, or sufficient time in what are sometimes difficult locations (Van 

Driesche et al. 2008). However, scientific work is cost‐effective in Malaysia compared to Options 1 and 2 

and our network of collaborators and cooperators is well established (Project 3b, Table 7).  Options 1  

(test in containment on Christmas Island) and 2 (test in containment on the Australian mainland) offer 

no benefits over this option.  We therefore suggest that host specificity testing is carried out in the 

native range of the biological control agent. This option carries the least risk and is consistent with 

Recommendation 2 in a review of biosecurity risks in biological control commissioned by the Australian 

Government (Ferrar et al. 2004) that biological control practitioners undertake host specificity testing in 

the native region before any importation. 

Protocol for insuring that hyperparasitoids associated with T. somervillei are not imported to 

Christmas Island.  The unintended importation of a hyperparasite of T. somervillei is inimical to the 

successful suppression of YCA supercolonies, because it could compromise the capacity of 

Tachardiaephagus to build up population densities sufficient to control Tachardina.  For this reason, 

great care will be taken to implement standard agent rearing and sanitary techniques to ensure that the 

founding population of Tachardiaephagus from Malaysia is free of hyperparasitoids and pathogens.  

33

Free‐living adults are the safest to import because this would ensure that hyperparasitoids would not be 

co‐introduced. 

Tachardiaephagus somervillei is frequently attacked by Promuscidea unfasciativentris (Aphelinidae) (see 

Project 2a; Table 1).  This hyperparasitoid was abundant near Kuching, Sarawak and present in Selangor, 

West Malaysia, although rare.  The impact of hyperparasitism is not known; nevertheless, the exclusion 

of any hyperparasitoids from captive colonies in Malaysia is critical before adult T. somervillei are 

imported to Christmas Island as the founding population.  

The exclusion of hyperparasitoids from captive populations at locations where the hyperparasitoids are 

native can be difficult in the long run unless care is taken.  Basic containment is usually sufficient but 

standard practices to keep hyperparasitoids out of captive populations must be followed. These include: 

Field collected, parasitized scale insects will never be exposed to laboratory scale insects directly; 

twigs with parasitized scale insects will be placed into emergence cages; emerging parasitoids will 

be examined individually before being removed from emergence cages. 

If hyperparasitoids (or any organism other than T. somervillei) are found in the emergence cages, 

they will be destroyed. 

Emergence cages will be kept in a dedicated room (the emergence room) in a separate building 

from that where the dedicated room with captive scale/parasitoid populations (the rearing 

facility) is located  

T. somervillei will be moved to the rearing facility and placed on host plants with suitable scale 

insect hosts in a mesh bag; the mesh bag ensures that parasitoids remain on the plant and the 

scale insects are protected. 

Mesh bags will not be removed (only shortly for monitoring purposes) from the plants until 

parasitoid emergence. 

When parasitoid emergence is expected, host plants with parasitized scales in their mesh bags 

will be moved to the emergence room. 

Personnel conducting field collections or any other field activity will not be allowed in the rearing 

facility on the same day. 

It is critical that the captive population is monitored continuously for hyperparasitoids even if best 

practices are followed closely.  In addition to individual examinations of parasitoids, yellow sticky cards 

will be used in both the emergence room and the rearing facility to monitor (and also trap) any 

hyperparasitoids or other insects.  Controlled exposures inside mesh bags will protect T. somervillei. 

The elimination of hyperparasitoids before importation to Christmas Island will involve the following 

steps.  First, the sanitary practices followed during rearing (see above) will ensure a "clean" captive 

population.  Second, emerged, adult parasitoids will be placed in airtight, glass vials.  All individual 

parasitoids will be inspected during the packing and hand‐carried from Kuala Lumpur to Christmas 

Island Airport.  All individuals will be examined again at the point of entry on Christmas Island while still 

in the glass vials (training of quarantine personnel on Christmas Island will be provided in advance); if in 

any doubt, the vial containing the questionable organism(s) will be destroyed.  Third, an individual 

examination will be conducted in the rearing facility on Christmas Island before the parasitoids are 

removed from the glass vials. 

 

In practice, the above procedures will ensure that hyperparasitoids are not transported to Christmas 

Island from Malaysia. 

34

Initial studies suggest that pathogens do not play a significant role in T. somervillei populations. In 

Malaysia, not a single T. somervillei, either field collected or lab reared, showed any signs of infection by 

entomopathogenic fungi or entomopathogenic nematodes. 

 

Key Research Outcomes:  an agreed, peer‐reviewed host list and host specificity protocol for evaluating 

risk of introduction of T. somervillei to Christmas Island to control the invasive yellow lac scale, 

Tachardina aurantiaca, with a recommendation that host specificity testing be conducted in the area of 

origin of Tachardina aurantiaca.  A protocol for ensuring that hyperparasitoids are not accidentally co‐

introduced with importation of T. somervillei to Christmas Island. 

    

35

Project 3d.  Rearing, release and monitoring protocols 

An agreed protocol for rearing and release of biological control agents, and pre‐ and post‐

release monitoring for their efficacy in controlling target scale insects. 

Research Findings 2009‐2013 

Protocol for mass rearing of Tachardiaephagus in Malaysia (FRIM) and import this population into a 

mass rearing facility on Christmas Island.  The transfer of the founder population from Malaysia to 

Christmas Island could be as simple as packaging freshly emerged adult T. somervillei inside a travel 

cooler to buffer them against extremes of temperature in transit.  The parasitoids should survive well 

without access to food or water for 48 hours.  There are direct flights between Kuala Lumpur and 

Christmas Island, but changes in scheduling may mean the parasitoids could be transported via Perth.  

This is the less desirable option because the probability of mortality is greater, and arrangements may 

have to be made with DAFF Biosecurity Australia to hold the agent in quarantine if there is a delay 

between flights.     

On Christmas Island, a production facility will have to be built to mass‐rear Tachardiaephagus for field 

release.  As in Malaysia, the maintenance of captive parasitoid populations depends on the production 

and maintenance of optimal host life stages of Tachardina on suitable host plants.  The best locally 

available host plant species for Tachardina are Inocarpus fagifer and Milletia pinnata.   

The major infrastructure item for this project will be a dedicated glasshouse/screenhouse (preferably 

closed, but solid‐roof screen house would probably be sufficient) for rearing of the biological control 

agent. Suitable host plants will be transferred to the glasshouse/screenhouse.  If chemical control of 

pests and diseases on host plants is needed at the nursery, host plants must remain uninfested in the 

glasshouse/screenhouse until insecticidal residues are no longer active.  Host plants can be inoculated 

with Tachardina within the same facility as long as plants in "waiting" and infested plants are separated 

with a barrier that prevents Tachardina crawler movement (e.g., a water moat system).  Availability of a 

second, smaller glasshouse/screenhouse, to serve as a backup should the colony of Tachardiaephagus 

fail in the primary glasshouse, would be optimal, although not absolutely necessary.   

Tachardina and Tachardiaephagus may be difficult to mass‐rear due to the relatively long life cycle of 

Tachardina (Project 2e, Table 5 ‐ from crawler stage to reproductive female is 80‐100 days, but 

generations overlap) and the need for fresh host plants (that may or may not be reused) on a regular 

basis.  Depending on the difficulty of rearing Tachardiaephagus, their availability for releases maybe 

limited at any given time.  As mass‐rearing methods improve and production increases on Christmas 

Island, the goal will be to provide the biological control agent for releases in all areas as needed.   

The population of Tachardiaephagus will require careful monitoring and maintenance to minimize any 

selection of laboratory‐adapted insects that perform poorly under field conditions. It may be necessary 

to replenish the genetic diversity of the captive population through the subsequent introduction of 

more insects from the founder population in Malaysia, or, more likely, from the field on Christmas 

Island once the initial releases have been conducted.  Population renewal will also counter the inherent 

susceptibility of microhymenoptera to the loss of population heterozygosity.  Sex determination in 

microhymenoptera is usually haplodiploid – males are haploid, females diploid, and heterozygosity at a 

multi‐allelic sex‐determining locus is required for femaleness.  Inbreeding can lead to a preponderance 

of homozygous diploids that will either be sterile males, or experience a very high rate of mortality.  

36

Field release of Tachardiaephagus.  The goal in releasing biological control agents is to generate 

sufficient ‘propagule pressure’ (e.g., the size of each release, the frequency of releases, and the number 

and spatial arrangement of release sites) to enable their successful establishment.  Increasing propagule 

pressure can enhance the likelihood of establishment by diminishing the role of chance (i.e., both 

demographic and environmental stochasticity), and potentially increase the rate of spread from release 

sites (Simberloff 2009).  Initial timing, number of individuals released, and the frequency of releases of 

both agents will depend on (a) the capacity and sustainability of mass rearing, (b) knowledge of the 

biology of Tachardiaephagus, especially in relation to its host, Tachardina; and, (c) the attributes of 

release sites.   

Criteria for choosing suitable primary release sites will include: (a) positive evidence of host scale 

infestation; (b) relatively high percentage of host plants of Tachardina or soft scale in the overstorey 

and understorey; (c) occurrence of a high‐density YCA supercolony or at least the presence of YCA; and, 

(d) site not subjected to current pesticide exposure (contact or systemic) or residues that could 

compromise establishment of the agents.  Some criteria (e.g., c and d) can be gleaned from the biennial 

Islandwide Survey (Green and O'Dowd 2009) and followed up by more detailed site assessments to 

determine (a) and (b).  Each release at a site is likely to involve a specified number of adult insects; 

specific methodology of release will largely depend on knowledge currently being gathered about 

Tachardiaephagus in Malaysia and parasitoids of soft scale insects (e.g. Coccophagus) already present 

on Christmas Island.  

Fipronil, the intoxicant in Antoff®, the bait currently used to control YCA supercolonies on Christmas 

Island, is known to affect the longevity, fecundity, and behaviour of some parasitoids (e.g., fipronil used 

in vineyards to control ants can have acute toxic effects on Anagyrus sp. nr pseudococci and 

Coccidoxenoides perminutus, two microhymenopteran parasitoids of mealybugs – Mgocheki and 

Addison 2009). Thus, exposure of the biological control agents at release sites to baiting (especially 

aerial baiting where a fine dust is produced and a fraction of the bait is retained in the canopy) must be 

avoided.  Coordination between field release and monitoring of biological control agents with National 

Parks staff involved in chemical control of YCA supercolonies will be critical during this phase of this 

project.    

Training on release methodology and criteria will be provided to National Park personnel.  Some 

additions to the Island Wide Survey (e.g., determination of host tree species composition, inspection of 

understorey for Tachardina and soft scale insects) could facilitate selection of release sites. 

Interrogation of the survey database to identify the baiting history at waypoints will be an essential 

precursor to release of the biological control agents.  The National Parks field crew will receive training 

in identifying and collecting scale insects and parasitoids. 

Monitor the establishment, spread, and impact of Tachardiaephagus and Coccophagus.  The absence 

of effective, quantitative monitoring for the establishment, spread and impact of most introduced 

biological control agents has been the Achilles’ heel of many biological control programs (McEvoy 1996).  

Estimation of the success or failure of many past biological control programs has relied on subjective 

measures, often post hoc expert opinion alone (e.g., DeBach et al. 1971, Greathead 1989, Griffiths and 

Julien 1998). For biological control on Christmas Island, protocols to quantify the establishment, 

population status, spread, and impact of biological control agents are essential.   

Two approaches will be used.  First, a field experiment will be conducted using a Before‐After‐Control‐

Impact design to determine the establishment and population dynamics of the agents, and the effect of 

37

their release on host scale densities (counts per length of stem or per leaf) and parasitization rates, both 

in the canopy (random sampling of host plant material collected using a shotgun) and in the 

understorey (from saplings of known host trees), and abundance of YCA (using counts on tree trunks 

and on the forest floor) at release and control sites before and after release of biological control agents.  

Sites (each 2‐4 hectares) would be sampled 4 times before release of the agents and 4 times afterwards 

at two monthly intervals. Results will be analyzed as a one‐way repeated measures ANOVA, using 

release of the biological control agents as the main factor, and comparing response variables before and 

after release. In this design, the time x treatment interaction is the key term, with a significant 

difference in response variables after, but not before release. Thus, this experiment at the forest plot 

scale would establish both the outcome of the release and the mechanism(s) driving any change in YCA 

abundance.   

Second, at the much broader, island‐wide scale the outcome of agents releases on YCA supercolonies 

will be determined by comparing changes in YCA trunk traffic and ground activity (using card counts) at 

four‐month intervals at replicated release and control sites across the island. The number of control 

sites will be determined based on the release sites and area availability.  Ideally, control sites should be 

distant enough from release sites so that the chances for biological control agent dispersal are low for a 

reasonable period of time. It will be necessary to determine how many of the selected release sites will 

be actually available for releases and the available areas for control sites where no other YCA 

management practices (i.e., application of toxic ant baits) will be applied. 

Spread of the biological control agents beyond release sites will be determined by placing potted 

‘sentinel’ host plants, infested with Tachardina or coccoid scales, at set distances (probably at a 

logarithmic scale) from replicated release points, followed by their later collection to determine 

parasitization rates with distance from each release point. It may also be feasible to use the biennial 

Island Wide Survey to document spread of the biological control agent, at least onto understorey 

seedlings and saplings, at waypoints surrounding release sites.   

 

Key Research Outcomes:  Identification of the requirements for the establishment of a founder 

population of Tachardiaephagus in Malaysia free of pathogens and hyperparasites, importation of this 

population under permit to Christmas Island, establishment and expansion of this population in a mass‐

rearing facility on Christmas Island, an agreed protocol for rearing and release of biological control 

agents, and pre‐ and post‐release monitoring for their efficacy in controlling target scale insects and 

reducing densities and impacts of the invasive yellow crazy ant Anoplolepis gracilipes.   

 

 

   

38

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44

Table 1.  Natural enemy assemblages of the yellow lac scale Tachardina aurantiaca on Christmas Island 

and in Malaysia.  + = present, ‐‐ = absent.  For associates of T. aurantiaca, primary parasitoids oviposit 

on or in a host and develop within, ultimately killing the host.  Hyperparasitoids seek out hosts with 

primary parasites, oviposit, and develop within the primary parasitoid.  Predators feed externally and 

consume multiple scales. 

Species (Family)  Association with T. aurantiaca 

Christmas Island  Malaysia 

Tachardiaephagus somervillei Mahdihassan (Encyrtidae) 

primary parasitoid  ‐‐  + 

T. sarawakensis Hayat et al. (Encyrtidae) 

primary parasitoid  ‐‐  + 

Coccophagus euxanthodes Hayat et al. (Aphelinidae) 

primary parasitoid  ‐‐  + 

C. tschirchii Mahdihassan (Aphelinidae) 

primary parasitoid  ‐‐  + 

Coccophagus sp. (Aphelinidae)1  primary parasitoid2  ‐‐  + 

Promuscidea unfasciativentris Girault (Aphelinidae) 

hyperparasitoid  ‐‐  + 

Aprostocetus (syn. Tetrastichus) purpureus Cameron (Eulophidae)1 

hyperparasitoid3  ‐‐  + 

Marietta leopardina Motschulsky 

(Aphelinidae) primary parasitoid4  +  + 

Eublemma sp. (Noctuidae)  predator  +  + 

?Holcocera sp. (Blastobasidae)  predator  +  + 

1Tentative identification; 

2Attack male T. aurantiaca only; 

3primary parasitoid of many Coccidae, Diaspididae, 

Kerriidae, Margarodidae, and Pseudococcidae but known as a hyperparasitoid of C. 

tschirchii and Tachardiaephagus sp.; 4On Christmas Island and in Malaysia, Marietta leopardina is known only to 

attack male T. aurantiaca. It has never been observed emerging from female T. aurantiaca.  In Southeast Asia, it is 

also a hyperparasitoid of primary parasitoids of a variety of scale insects.  

 

 

 

 

 

   

45

Table 2.  Parasitization rates on mature females of Tachardina aurantiaca in the native range (Southeast 

Asia) and in the introduced range (Christmas Island).  Parasitization rates were calculated as the 

proportion of mature female scale insects with one or more visible parasitoid emergence hole, either in 

isolated aggregates (N = 5) at sites in Southeast Asia or pooled within sites on Christmas Island (N is in 

brackets).  This gives rates of parasitization at each site, but not the identity of the parasitoids.  However, 

only T. somervillei was collected at sites in Kuching and Singapore.  All other locations in Southeast Asia 

had a parasitoid assemblage of more than one species.  For Christmas Island, number in parentheses 

after site name indicates the total number of mature females examined. 

 

Location Rate of Parasitization 

(%, mean ± SE) 

Native range (Southeast Asia)   

Klang (Selangor, West Malaysia)  38 ± 17 

Taman Ehsan (Selangor, West Malaysia)  46 ± 21 

Singapore (National University Singapore campus)  73 ± 12 

Kampung Istana, Kuching (Sarawak)  42 ± 23 

Kampung Boyan, Kuching (Sarawak)  81 ± 6 

Sandakan (Sabah)  76 ± 8 

Sepilok (Sabah)  29 ± 13 

Introduced Range (Christmas Island)   

The Dales (Hugh’s – Sydney’s) (4000)  0 ± 0 

Martin Point to CINP Boundary (1500)  0 ± 0 

Dolly Beach Track (1000)  0 ± 0 

North West Point Track (1500)  0 ± 0 

Circuit Road (2000)  0 ± 0 

 

   

46

Table 3.  Records of known host families and genera for the primary parasitoid Tachardiaephagus 

(Encyrtidae).  Taxonomy follows Prinsloo (1977).  The biological control agent under investigation, 

Tachardiaephagus somervillei, is in bold. As a genus, Tachardiaephagus has an extremely broad 

geographic range. With the exception of one probably erroneous host record in Africa (Prinsloo 1983), 

all Tachardiaephagus species appear to be family specialists and restricted to the Kerriidae. For host 

genera, number of species recorded as hosts is in parentheses.  Based on Noyes (2012, Universal 

Chalcidoidea Database, http://www.nhm.ac.uk/research‐

curation/research/projects/chalcidoids/database/), except for records for T. somervillei and T. 

sarawakensis (Hayat et al. 2010; R.W. Pemberton, pers. comm.). 

 

 

Parasitoid species  Distribution  Recorded hosts (all Kerriidae) 

Tachardiaephagus somervillei 

India, Malaysia, Thailand      Kerria spp. (4)1 

    Tachardina aurantiaca 

   Tachardina sp.2   

T. sarawakensis  Sarawak (East Malaysia)    Tachardina aurantiaca 

T. tachardiae  Brunei, China, India, Indonesia, Malaysia, Sri Lanka, Taiwan, Vietnam, Azerbaijan 

  Kerria spp. (8)  

  Paratachardina lobata 

T. similis  Afrotropical, South Africa    Tachardina sp. (1) 

T. absonus  Afrotropical, South Africa    Tachardina spp. (2) 

T. communis  Afrotropical, South Africa    Tachardina spp. (5) 

T. gracilis  Afrotropical, South Africa    Tachardina sp. (1) 

1In Noyes (2012) both Kerria and Laccifer species are listed as hosts.  However, Scalenet (Ben‐Dov et al. 2012) indicates that Laccifer is a synonym for Kerria, so we have synonymized these records with Kerria species.   

2 Probably T. aurantiaca, since it is the only known Tachardina species in Asia.  

 

47

Table 4.  Scale insects of Christmas Island. It is highly probable that all of these species, with broad host 

plant ranges and geographic distributions, are exotic to Christmas Island and introduced following 

human settlement. The target species, Tachardina aurantiaca, for biological control is in bold. 

Honeydew‐producing scale insects in bold occur commonly tended by YCA in supercolonies. Families are 

arranged in increasing phylogenetic distance from the Kerriidae based on Gullan and Cook (2007) and 

Ross et al. (2012).  All scale insect taxa are 'neococcids' except for Icerya purchasi ('archeococcid').  

Taxonomy and distributions from Ben‐Dov et al. (2012), http://www.sel.barc.usda. 

gov/scalenet/scalenet.htm).   

 Family and Species1  

Common Name  Distribution Honeydew Producer 

Kerriidae (lac scales)   Paratachardina pseudolobata           (Kondo & Gullan)   Tachardina aurantiaca (Cockerell)    

 

False lobate lac scale  Yellow lac scale 

Oriental, Nearctic, Neotropical Oriental 

yes2  

yes 

Coccidae (soft scales)   Ceroplastes ceriferus (Fabricius)   C. destructor Newstead    Coccus celatus De Lotto      C. hesperidium Linnaeus   Milviscutulus mangiferae (Green)   Parasaissetia nigra (Nietner)    Pulvinaria urbicola Cockerell    P. psidii Maskell3   Saissetia coffeae (Walker)   S. oleae (Olivier) 

 

Indian wax scale White wax scale  Green coffee scale  Brown soft scale Mango shield scale Nigra scale Urbicola soft scale Green shield scale Black olive scale Hemispherical scale 

Cosmopolitan Afrotropical, Australasia, Oriental Afrotropical, Australasia, Oriental Cosmopolitan Cosmopolitan Cosmopolitan Pantropical Cosmopolitan Pantropical Cosmopolitan 

yes yes  

yes  

yes yes yes yes yes yes yes 

Diaspididae (armoured scales)    Aspidiotus destructor (Signoret)    Hemiberlesia palmae (Cockerell)     Ischnaspis longirostris (Signoret) 3   Lindingaspis sp.   Pseudaulacaspis pentagona   (Targioni Tozzetti)   Unaspis citri (Comstock) 

 

Coconut scale Tropical palm scale Black thread scale ‐‐ White peach scale  White louse scale 

Cosmopolitan Cosmopolitan Cosmopolitan ‐‐ Cosmopolitan  Cosmopolitan 

no no no ‐‐ no  

no 

Cerococcidae (ornate pit scales)   Cerococcus indicus (Maskell) 

 

Spiny brown coccid  Cosmopolitan  yes? 

Pseudococcidae (mealybugs)   Dysmicoccus finitimus Williams  Asian coconut mealybug  Australasia, Oriental  yes 

  Ferrisia virgata (Cockerell)  Nipaecoccus viridis (Newstead)  Pseudococcus longispinus     (Targioni Tozzetti) 

Monophlebidae (giant scales)   Icerya purchasi (Maskell) 

Striped mealybug Spherical mealy bug Long‐tailed mealy bug 

  Cottony cushion scale 

Cosmopolitan Cosmopolitan Cosmopolitan   

Cosmopolitan 

yes yes yes   

yes 

1Records from Campbell (1968), CSIRO (1999), O'Dowd et al. (2003), Bellis et al. (2004), Abbott (2004), Woods and Steiner (2012) and Neumann et al. (unpubl. results);  2Paratachardina pseudolobata produces honeydew but eject it instead of producing droplets that can be collected by ants (Howard et al. 2010) 3Tentative identifications

48

Table 5.  Time (days ± SE) from crawler stage to emergence of either (a) adult males or (b) the 

production of the next generation of crawlers from adult females in Tachardina aurantiaca on 

seedlings of Acacia mangium x A. auriculiformis (n = 6), Milletia sp. (n = 7) and Inocarpus fagifer (n = 

6) under laboratory conditions.  All host plants were potted plants less than 1 m tall.  Observations 

on hosts A. mangium x A. auriculiformis and Milletia sp. were conducted in at the Forest Research 

Institute of Malaysia in West Malaysia (Ong and Neumann, unpublished results). Observations on I. 

fagifer were conducted on Christmas Island. 

   

 Acacia mangium x A. 

auriculiformis Milletia sp.  Inocarpus fagifer 

(a) Days to male 

emergence 

40.1 ± 0.2  41.71 ± 0.13  42.5 ± 1.3 

(b) Days to female 

crawler production 

87.6 ± 0.2  98.3 ± 0.5  99.7 ± 1.2 

49

Table 6.  Key Australian government contacts for progressing the importation and release of an exotic biological control agent on Christmas Island, Indian Ocean.  Framework refers either to the DAFF protocol for biological control agents or the Environmental assessment procedure under the EPBC Act (EACD, DSEWPaC)  

Framework  Issue (Key URL)  Section  Key contact  Addresses 

DAFF  

Import risk analysis 

(http://www.daff.gov.au/ba/reviews/biological_control_agents/risk_analyses) 

 

Grains & Forestry, DAFF 

Tara Dempsey Assistant Manager, Processed Products, Biologicals & Pacific Plant Biosecurity, DAFF  

tara.dempsey@daff.gov.au 

craig.hull@daff.gov.au 

 

Nomination of a target species for a biological control agent (http://www.daff.gov.au/ba/reviews/biological_control_agents/protocol_for_biological_control_agents/guidelines‐introduction‐exotic‐bcas‐weed‐and‐plants) 

Approvals package to import and release an exotic biological control agent (URL as for nomination) 

Office of the Plant Protection Officer, Plant Health Committee 

Susie Collins Secretariat, Plant Health Committee, OCPPO 

phc@daff.gov.au

susie.collins@daff.gov.au 

ryan.genero@daff.gov.au 

 

 

Amendment to live imports list (http://www.environment.gov.au/biodiversity/wildlife‐trade/lists/import/index. html)  

Wildlife Trade Regulation, DSEWPaC 

Michelle van der VoortWildlife Trade Regulation Section, DSEWPaC 

exotic.species@environment.gov.au michelle.vandervoort@environment.gov.au 

EACD  Environmental referral and assessment (http://www.environment.gov.au/epbc/assessments/index.html) 

Environmental Assessment and Compliance Division, DSEWPaC 

Felicity McLean Assistant Secretary, Northwest Section, EACD, DSEWPaC 

 

felicity.mclean@environment.gov.au michael.ward@environment.gov.au 

   

50

Table 7.  Established collaborators and cooperators for the biological control project.   

Location  Collaborator  Expertise 

Australia 

  ANU, Biological Sciences             

University of Queensland,   Biological Sciences 

 

Prof. Penny Gullan 

 Dr. Lyn Cook 

 

Biology and phylogeny of scale insects 

Phylogeny and genetics of scale insects 

India 

  Aligarh Muslim University,   Aligarh, Uttar Pradesh 

 

Dr. Mohammed Hayat 

 

Microhymenopteran taxonomy 

Peninsular Malaysia 

  Forestry Research Institute   Malaysia (FRIM)                                      

  Universiti Sains Malaysia 

 

Dr. Laurence Kirton 

 Ms Ong Su Ping 

 

Entomology 

 Entomology (M.Sc student) 

Sarawak 

  Sarawak Forestry, Botanical  Research Centre, Semenggoh   

 

Ms Lucy Chong 

Mr Het Bin Kaliang 

 

Entomology 

Entomology 

Sabah 

  Sabah Forestry Department,    Forest Research Centre,   Sepilok 

 

Dr. A. Chung Yaw Chyang 

Dr. Chey Vun Khen 

 

Entomology 

Entomology 

Singapore 

  National University of   Singapore (NUS), Biological   Sciences 

 

Dr. Rudolf Meier 

Dr. Hugh Tan Tiang Wah 

 

Entomology 

Entomology 

United States 

  USDA‐ARS, Invasive Plant  Research Laboratory, Ft.   Lauderdale FL   

 

Dr. Robert Pemberton 

 

 

 Biological control of insects and weeds in natural areas, biosafety 

 

   

51

Table 8.  Expert ad hoc reviewers for the host test list and host‐specificity testing protocol (Project 

3c).  All of these colleagues have agreed to continue to advise us on this and other aspects of the 

project.  

Reviewer  Expertise 

Australia 

Dr Don Sands OAM, CSIRO Ecosystem Sciences, Brisbane QLD 

 

Biological control of scale insects 

New Zealand 

Dr Barbara Barratt, Principal Scientist, AgResearch Invermay, Biocontrol, Biosecurity and Bioprocessing, Mosgiel, New Zealand 

 

Biosafety of biological control agents, risk assessment, biocontrol in natural areas, developed the BIREA (Biocontrol Information Resource for EPA Applicants) for New Zealand 

Switzerland 

Dr. Tim Haye, Commonwealth Agricultural Bureaux International, Geneva 

 

Host range assessment and impacts of parasitoids. 

United States 

Dr. Robert Pemberton, USDA‐ARS Invasive Plant Research Laboratory, Ft. Lauderdale FL 

Dr. Matthew Purcell, Team Leader,  USDA‐ARS,  Australian Biocontrol Laboratory, Brisbane QLD 

 

Biological control of insects and weeds in natural areas, biosafety, biocontrol of the lobate lac scale 

Biological control of insects and weeds 

 

52

Table 9.  Endemic hemipteran species known from Christmas Island and primary parasitoids 

(superfamily Chalcidoidea: family Encyrtidae) associated with the families represented by the 

endemic species.  The data were extracted from the Universal Chalcidoidea Database (Noyes 2012).  

The families Nogodonidae and Rhopalidae have no associated chalcidoid primary parasitoids and 

therefore endemic species in these families on Christmas Island can most likely be excluded from all 

further consideration.  Cicadellidae and Delphacidae have the highest diversity of chalcidoid primary 

parasitoids but have magnitudes lower diversity of encyrtid primary parasitoids.  These data suggest 

that the encyrtid primary parasitoids of families with endemic species on Christmas Island appear to 

not have host range overlap with taxa where the target lac scale is included and the host range 

separation is at the suborder level suggesting very distant phylogenetic separation.  During the 

database analysis, only records with species‐level chalcidoid identification were used.  N/A indicates 

not applicable 

1 Xestocephalus izzardi is also reported from Palau in the western Pacific Ocean (Linnavuori 1975).  Its status as an endemic on Christmas Island is questionable. 2 Leptocoris subrufescens on Christmas Island has been classified to subspecies status (L. subrufescens subrufescens,). Another subspecies (L. s. flava) is described from Yap, western Pacific Ocean (Göllner‐Scheiding 1980). More research is needed to resolve the taxonomic status of these two subspecies of L. subrufescens.  

   

Endemic species  Family  No. chalcidoid associates of family 

No. encyrtid 1o parasitoid species 

of family 

Suborder/Family host range of encyrtids parasitizing family 

Xestocephalus 

   Izzardi1 

Cicadellidae  627  6  Auchenorrhyncha 

(Cicadellidae) 

Oxypleura 

   calypso 

Cicadidae  35  0  N/A 

Clovia eximia  Cercopidae  71 4 Auchenorrhyncha 

(Cercopidae‐ 

Aphrophoridae) 

Ugyops aristella  Delphacidae  248  5  Auchenorrhyncha 

(Delphacidae‐ 

Cicadellidae) 

Varcia 

   flavicostalis 

Salona oceanica 

Nogodinidae  0  N/A  N/A 

Leptocoris 

  subrufescens2  

Rhopalidae  0  N/A  N/A 

 

53

 

 

 

 

 

 

 

 

Figure 1.  The yellow lac scale Tachardina aurantiaca is estimated to contribute a 

large fraction of the honeydew economy at forest sites with YCA supercolonies.  

At each site the estimated range in % contribution to SHI by T. aurantiaca is given, 

based on per capita parity in honeydew production by T. aurantiaca and coccoid 

scale insects (blue circles, mean = 70%, range 46‐86%) or a 3 times greater per 

capita honeydew production by T. aurantiaca (red circles, mean 86.5%, range 72 – 

95%).   

   

0

10

20

30

40

50

60

70

80

90

100

70 80 90 100 110 120 130

% Contribution by Tachardina in

 2000

Site Honeydew Index in 2000

54

 

Figure 2.  Estimated change in the Site Honeydew Index specifically for Tachardina 

aurantiaca on Inocarpus fagifer from 2000‐2012, at eight 0.25 ha sites in former 

YCA supercolonies. Numbers on the y‐axis are an index of Tachardina abundance 

and follow the methodology for calculation of the SHI, but applied only to 

Inocarpus.  

   

0

10

20

30

40

50

60

70

80

SHI o

f Tachardinaon In

ocarpus

2002 2012

55

 

 

 

 

 

Figure 3. Stable isotope analyses (δ15N) of yellow crazy ants from four declining 

supercolonies showed that trophic position increased (i.e. YCA became more 

carnivorous) as population densities decreased over 16 months in 2010‐2011.  In 

this figure, a trophic position > 3 indicates stronger carnivory while < 3 indicates 

increasing herbivory. The datapoints are connected in temporal order for each 

site, beginning at the right‐hand side.   

 

    

2.4

2.6

2.8

3.0

3.2

3.4

3.6

1 10 100 1000

Trophic Position

YCA abundance (no. ants 30 s‐1) 

Site 206

Site 318

Site 403

Site 582

56

 

  

Figure 4. Banding trees effectively excluded YCA from honeydew resources in the 

forest canopy (A), resulting in a precipitous decline and the virtual elimination of 

YCA traffic on tree boles 4 weeks after the tree bands were in place (B).  Red 

symbols indicate control plot (unbanded trees), blue symbols indicate treatment 

plot (banded trees).  Solid black line indicates when the bands were applied. 

   

0

5

10

15

20

25

30

35

40

45

50

YCA trunk counts (no. ants 30 s‐1

B 

A 

57

Figure 5. Mean YCA abundance was estimated from replicate counts of the number of ants crossing 

one quadrant of a 20 cm x 20 cm card in 30 s (A).  Exclusion of the yellow crazy ant from the forest 

canopy resulted in a significant and rapid decline in YCA abundance on the forest floor; YCA abundance 

fell and diverged markedly from the control plot two weeks after tree bands were placed (B).  Red 

symbols indicate control plot (unbanded trees), blue symbols indicate treatment plot (banded trees).  

Solid black line indicates when the bands were applied. 

A

0

5

10

15

20

25

30

35

40

45

YCA ground counts (n0. card‐130 s‐1)

B

58

 

 

 

 

 

 

Figure 6.  Performance and foraging behaviour 

of yellow crazy ants depend on sugar supply. 

(A) Per capita recruitment to sugar indicated 

that a smaller fraction of colony workers is 

needed to collect sugar with increasing sugar 

supply. Colony performance, as measured by 

(B) production of workers and males increased 

with sugar availability whereas per capita 

death rate decreased (C) with increasing sugar 

availability. Per capita foraging tempo also 

increased with sugar supply (D). 

0

0.02

0.04

0.06

0.08

0 1 2 3 4

Per capita no. Y

CA feeding

0

100

200

300

400

500

600

0 1 2 3 4

No. n

ew in

dividuals

P = 0.001

0

0.1

0.2

0.3

0.4

0.5

0 1 2 3 4

Per capita no. Y

CA dead

P = 0.025

A

B

0.000

0.005

0.010

0.015

0.020

0.025

0 1 2 3 4

Per cap

ita no.YCA exploring 

novel o

bject

log total sugar delivered (mg)

P = 0.012

D

C

59

 

 

  

Figure 7.  Aggressive behaviours in the yellow crazy ant increased with sugar supply. 

YCA with access to more sugar sprayed P. megacephala with formic acid sooner more 

often (A), and killed more P. megacephala in 3:3 interaction trials (B). 

   

0

1

2

3

4

0 1 2 3 4 5

No. tim

es YCA spray

P < 0.001

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0 1 2 3 4 5

No. d

ead

 P. m

egacephala

log total sugar delivered (mg)

P = 0.077

A

B

60

 

 

 

 

 

 

 

Figure 8.   Christmas Island (red circle) is the only known area of introduction and 

invasion of the yellow lac scale Tachardina aurantiaca (Kerriidae).  Yellow symbols 

indicate sites in Peninsular Malaysia (Penang Island, Klang, Selangor, Singapore) and 

Malaysian Borneo (Sarawak ‐ Kuching; Sabah ‐ Sandakan, Sepilok) where live 

aggregates of Tachardina were found. 

   

Christmas Island

61

Figure 9.  Parasitism of the yellow lac scale Tachardina aurantiaca in Malaysia.  A.  

Parasitoid emergence holes of Tachardiaephagus sp. (Encyrtidae) in tests of an 

aggregate of old adult females of T. aurantiaca on Milletia pinnata near Sandakan, 

Sabah, Malaysian Borneo.  Yellow crazy ants (Anoplolepis gracilipes) tended T. 

aurantiaca at this site.  B. Emergence holes of Coccophagus euxanthodes 

(Aphelinidae) in the test of a T. aurantiaca on Acacia auriculiformis at Klang, 

Selangor, Peninsular Malaysia.  The smaller opening in the centre of the test is the 

anal pore through which honeydew is produced. Weaver ants (Oecophylla 

smaragdina) tended T. aurantiaca at Klang.   

   

A B

62

 

 

 

Figure 10.  Tachardiaephagus somervillei, a primary parasite of the yellow lac scale 

Tachardina aurantiaca in Malaysia and Singapore (drawing from Narayanan 1962).  

In initial studies in 2011‐2013, T. somervillei attacked T. aurantiaca across 

Peninsular Malaysia and Malaysian Borneo, is the most abundant natural enemy of 

T. aurantiaca, exhibited superparasitism (i.e., where multiple progeny emergence 

from a single host individual), and heavily parasitized T. aurantiaca in the presence 

of tending ants, including the yellow crazy ant.  T. somervillei can be reared under 

laboratory conditions (Ong and Neumann, unpublished results). 

 

   

1 mm

63

 

 

 

 

 

 

Figure 11.  The positive and significant relationship between female size of the 

yellow lac scale Tachardina aurantiaca and the number of progeny of the parasitoid 

Tachardiaephagus somervillei emerging from each host scale under field conditions 

in Malaysia (R2 = 0.471, N = 50 females, p < 0.01).  

 

 

 

   

0

1

2

3

4

5

1.0 1.5 2.0 2.5 3.0 3.5 4.0

No. o

f progeny of T. somervillei

Female T. aurantiaca size (mm)

64

 

 

 

 

 

 

Figure 12.  Search methodologies for detecting native or endemic scale insects and 

natural enemies of the yellow lac scale T. aurantiaca on Christmas Island.   

Northwest Point is enlarged in the upper left‐hand side of the figure.   

   

65

 

 

 

 

 

Figure 13.  Size‐dependent fecundity of female Tachardina aurantiaca under 

laboratory and field conditions, across a range of plant hosts.  Female size was 

determined by measuring the test at the greatest horizontal diameter with callipers.  

The number of crawlers was determined by dissecting the females shortly before 

crawler release.  There is a significant correlation between female size and number 

offspring produced (laboratory, open circles: R2 = 0.295, p < 0.001, n = 50; field solid 

circles: R2 = 0.207, p = 0.006, n = 50)(Ong and Neumann, unpublished results). 

 

 

   

0

100

200

300

400

500

600

700

2.0 2.5 3.0 3.5 4.0 4.5 5.0

No. crawlers / female

Female size (mm)

66

 

 

Figure 14. Portion of a phylogram of the scale insects based on nucleotide 

sequencing of nuclear 18S rRNA for 72 species of scale insects and 10 outgroup taxa 

(see Gullan and Cook [2007] for details). Only the neococcoids (red) are shown here. 

For all families given here (except the Kermesidae), Bayesian posterior probabilities 

(numerical values above branches) are > 90%.  For a host test list, we will select 

species from those families given in bold.  The lac scales Kerriidae (bold and italics) 

is a sister family of the soft scales (Coccidae), more distant to the armoured scales 

(Diaspididae), and even further removed from the mealybugs (Pseudococcidae). 

 

Pseudococcidae

Coccidae

Kerriidae

Kermesidae

Diaspididae

Gondwanan clade

BSE clade

Asterolecaniidae

Acanthococcid group

Dactylopiidae

Tropical Ecosystems Research Centre

PMB 44 Winnellie, NT 0822, Australia

T (03) 8944 8400 • ABN 41 687 119 230

CSIRO ECOSYSTEMS SCIENCES

15 January 2013 Mr Mike Misso Manager, Christmas Island National Park mike.misso@environment.gov.au Dear Mike, During CASAP’s meeting on 12 December 2012 we considered the executive summary of the report ‘Research and development for indirect biological control of the yellow crazy ant (Anoplolepis gracilipes) on Christmas Island, Indian Ocean’. Drs Green and O’Dowd were excused from this consideration due to their significant roles in the writing of the report. The report summarises results of research related to the potential use of biocontrol of the scale insect Tachardina aurantiaca as a means of controlling crazy ant infestations on Christmas Island. The research shows that: (1) The supply of liquid carbohydrate plays a key role in the dynamics of crazy ant colonies on CI; (2) T. aurantiaca is a key provider of liquid carbohydrate on CI; (3) In contrast to CI, within its native range in Malaysia T. aurantiaca has a diverse range of natural enemies, and is rare and patchily distributed; (4) In Malaysia, T. aurantiaca has high rates of parasitism by the encyrtid Tachardiaephagus somervillei , which appears to specialise on the family Kerriidae (not native to CI) and can be reared under laboratory conditions. The report concludes that prospects of successful biocontrol are good, and therefore the biocontrol program should proceed. CASAP members were unanimously of the view that the research had very high scientific merit, and effectively demonstrates the potential for successful biocontrol. It was considered that the risks associated with introducing a bio-control agent were low, particularly given existing bio-security risks on CI. CASAP endorses the conclusion of the report that the biocontrol program should proceed, and recommends that it covers soft scale as well as T. aurantiaca, since it is highly feasible and requires minimal extra resources to do so. Yours sincerely,

Prof Alan N. Andersen Chair, Christmas Island Crazy Ant Scientific Advisory Panel Alan.Andersen@csiro.au (08) 8944 8431

1

Host specificity testing of Tachardiaephagus somervillei (Hymenoptera: 1

Encyrtidae), a biological control agent for the yellow lac scale 2

Tachardina aurantiaca (Hemiptera: Kerriidae) 3

G. Neumann1, D.J. O'Dowd2 and P.T. Green1 4

1Department of Botany, La Trobe University, Bundoora, Victoria 3086 Australia and 2School of 5

Biological Sciences, Monash University, Melbourne, Victoria 3800 Australia 6

7

Preamble 8

The yellow lac scale, Tachardina aurantiaca (Hemiptera: Kerriidae) is a damaging, invasive 9

pest on Christmas Island (Indian Ocean) and implicated in the formation of widespread, high-10

density supercolonies of the invasive yellow crazy ant (Anoplolepis gracilipes) (O'Dowd et al. 11

2003, Abbott and Green 2007). Suppression and control of crazy ant supercolonies may be 12

afforded by the importation and release of Tachardiaephagus somervillei (Hymenoptera: 13

Encyrtidae), a widespread and abundant parasitoid of Tachardina that is known to parasitize 14

lac scales in its native range in Southeast Asia (Hayat et al. 2010, Green et al. 2013). Below we 15

provide a ‘desktop’ evaluation (Sands and Van Driesche 2004) of risk of importation and 16

release of T. somervillei on Christmas Island and then describe a protocol for host-specificity 17

testing recommending that it be conducted in the area of origin of Tachardina aurantiaca. 18

19

1. Evaluation of risk based on host records of Tachardiaephagus from the 20

scientific literature, hemipteran diversity on Christmas Island, and host 21

records of encyrtid parasitoids 22

To focus host-specificity testing for Tachardiaephagus somervillei, we used four approaches to 23

assess the risk of importation and release of the exotic biological control agent T. somervillei 24

to Christmas Island. All four lines of evidence indicate that there is a very low likelihood that 25

importation and release of T. somervillei would harm species of concern on Christmas Island. 26

27

1.1 Known host range of Tachardiaephagus somervillei 28

We evaluated known host species records for all species of Tachardiaephagus using the 29

Universal Chalcidoid Database (Noyes 2012) so that host range could be estimated and risk of 30

release of T. somervillei assessed for species of concern on Christmas Island. The Universal 31

Chalcidoidea Databases (Noyes 2012) is the most comprehensive database for chalcidoid 32

parasitoids, with over 120,000 host/associate records (including associations with food plants 33

of the hosts) and > 140,000 distribution records of the parasitoids in the superfamily 34

Chalcidoidea. It is very well developed, regularly updated and extremely well referenced. 35

Nevertheless, large databases can contain errors affecting reliability, such as erroneous 36

2

published host records and outdated parasitoid taxonomy (Kuhlmann et al. 2006). The most 37

important source of error in this database is actual published erroneous records. Since all 38

records are referenced, doubtful records can be investigated and if necessary, filtered out. 39

Seven described species of Tachardiaephagus are distributed in Southeast and South Asia, 40

and sub-Saharan Africa (Noyes 2012). Host records of Tachardiaephagus are restricted to 41

species within three genera (Kerria, Tachardina, and Paratachardina) of lac insects (Kerriidae) 42

(Table 1). Furthermore, all host species records for Tachardiaephagus somervillei are within 43

two genera: Kerria, comprising the lac insects of commerce, and Tachardina. These records 44

suggest that Tachardiaephagus somervillei is highly likely to have a narrow host range 45

restricted to kerriid host species. 46

47

1.2 Status of other scale insects on Christmas Island 48

We determined insect species on Christmas Island that could conceivably constitute non-49

target species. Records for occurrence of scale insect species (Superfamily Coccoidea, the 50

same superfamily to which Tachardina aurantiaca belongs) on the island were compiled from 51

the literature and then supplemented by conducting >400 hours of structured search over 52

two years for endemic scale insects (Green et al. 2013). For specimens from the structured 53

search, all identifications were verified by Prof Penny Gullan (Australian National University), 54

a scale insect systematist. 55

A total of 24 species of scale insects in six families have been recorded on Christmas Island 56

(Table 2). All scale insects that could be considered as the most likely potential non-target 57

organisms are non-natives on Christmas Island and none are beneficial (Table 2). 58

59

1.3 Phylogeny of endemic hemipterans 60

The closest endemic relatives of the yellow lac scale on Christmas Island should be considered 61

to evaluate the risk of becoming non-target hosts of Tachardiaephagus somervillei. We 62

obtained a list of known endemic insect species on Christmas Island (James and Milly 2006) 63

and narrowed consideration of taxa on this list to the closest endemic relatives of lac scales 64

on Christmas Island in the Order Hemiptera, the same order to which the known target 65

species Tachardina aurantiaca belongs. These species comprise one true bug, a cicada, a 66

leafhopper, a spittlebug, and three planthoppers (Table 3). All of these endemic species occur 67

in different suborders (either suborder Auchenorrhyncha or Heteroptera) than the yellow lac 68

scale (suborder Sternorrhyncha). 69

70

71

72

3

Thus, any potential for non-target impacts by T. somervillei on these endemic Hemiptera 73

would require a host range that bridges this very substantial phylogenetic distance (see above 74

and Fig. 2 in Cryan and Urban 2012), as well as distinctive morphologies, life-histories and 75

ecological attributes to its known host taxa in the Kerriidae. 76

77

1.4 Host ranges of encyrtid parasitoids known to attack members of the hemipteran 78

families with endemic species on Christmas Island. 79

The Encyrtidae (Hymenoptera, Superfamily: Chalcidoidea), the family to which T. somervillei 80

belongs, is one of the most important parasitic wasp (parasitoid) families for the biological 81

control of harmful insects, including a variety of scale insects infesting woody plants (Noyes 82

and Hayat 1994, Noyes 2012). The Encyrtidae currently comprises 460 genera and 3735 83

species in 2 subfamilies. The subfamily Encyrtinae includes 353 genera and 2920 species, 84

while the Tetracneminae includes 107 genera and 815 species. Approximately half of all 85

encyrtid species are associated with scale insects (Hemiptera: Coccoidea)(Noyes 2012). 86

Encyrtids are generally endoparasitoids meaning that the parasitoid egg is laid directly inside 87

the host’s body where the hatching larva completes development feeding on the host’s 88

tissue, ultimately killing the host. Encyrtids mostly parasitize immature life stages (or, rarely, 89

adults), but some species in one genus (Microterys) are egg predators (Noyes 2012). 90

We used the Universal Chalcidoidea Database to analyze all records of encyrtid parasitoid 91

associates of the hemipteran families represented by endemic species on Christmas Island. 92

Next, all recorded primary hosts of encyrtid species associated with these taxa were 93

determined. Consequently, any encyrtid species that share (as hosts) both coccoid species 94

(scale insects) and any family represented by endemic species on Christmas Island could be 95

found. 96

There are no known records in the Encyrtidae of any parasitoid species that attacks both scale 97

insects (Coccoidea) and host species in hemipteran families that have endemic 98

representatives on Christmas Island (Table 3). All known encyrtid primary parasitoids known 99

to attack species in families which have endemic representatives on Christmas Island have 100

primary hosts only within suborder Auchenorrhyncha. While species in these hemipteran 101

families are attacked by many species of chalcidoid parasitoids, many fewer or no encyrtid 102

species are known to use them as hosts, and not one encyrtid species is reported with a host 103

range so extremely broad that it encompasses both scale insects and any of these hemipteran 104

families. 105

106

2. Host specificity testing protocol 107

Actual records for host range of Tachardiaephagus and known patterns of parasitism in the 108

Encyrtidae indicate that it is highly improbable that T. somervillei would exhibit an extremely 109

broad host range (one that would be unprecedented in any single species of Encyrtidae 110

4

known to attack scale insects) and utilize any of the endemic hemipteran species on 111

Christmas Island. 112

2.1 Terminology 113

A ‘test species’ is an insect species that is tested as a potential non-target insect. Since no 114

non-target scale insects were identified on Christmas Island, the list of test species will be 115

determined using the centrifugal approach (Kuhlmann et al. 2006, Neumann et al. 2010). In 116

this approach, species other than the known target host of the biological control agent are 117

tested with the most closely related species (least phylogenetic distance, and with close 118

similarities in biology and ecology) tested first then less similar species thereafter (“centrifugal 119

principle” - Wapshere 1974). 120

A test species will be considered a ‘suitable host’ if parasitoid emergence is observed during 121

any of the exposure tests. To be a suitable host, the parasitoid must (a) accept the test 122

species when exposed, (b) must oviposit, (c) the eggs must hatch into larvae, (d) the larvae 123

must complete development using the test species as the resource, (e) the larvae must 124

pupate and, finally, (f) the emerging adult parasitoid must be able to exit (emerge from) the 125

test species. If parasitoid emergence from a test species is observed, the test species will be 126

considered a suitable host without assessing the viability, fecundity, sex ratio and other 127

characteristics of the emerging parasitoid generation. 128

A test species will be considered ‘susceptible’ if the parasitoid causes significant mortality due 129

to probing, host feeding (when the parasitoid stabs the insect with its ovipositor and then 130

feeds on the insect’s hemolymph), oviposition, or oviposition and larval development. Note 131

that even if some mortality is observed due to the above, the test species will only be 132

considered susceptible if the mortality resulting to the exposure to the parasitoid is 133

significantly higher than in control groups (negative controls) of the test species where the 134

test individuals are not exposed to the parasitoid. 135

The ‘parasitoid’ in this case is T. somervillei (Hymenoptera: Encyrtidae), a widespread 136

parasitoid native to Southeast Asia. It is known to parasitize some scale insects in the family 137

Kerriidae (lac scales) including the ‘target host’, Tachardina aurantiaca (O’Dowd et al. 2012). 138

2.2 Selecting test species 139

Host specificity testing can be a long and difficult process, depending on how problematic it is 140

to establish and manage colonies of the parasitoid, the target host, the host plant of the 141

target host, and the test species. Furthermore, resources and time are not unlimited and 142

permitting issues to collect insects and run field experiments (when needed) in Malaysia can 143

add to the time required to complete host testing. Therefore, a manageable number of 144

species should be used (10 to 15, but fewer are acceptable if high specificity is found initially). 145

The species used will be largely determined by availability, so determining the actual test 146

species at species or genus level is not possible at this point. We can, however, predict to 147

5

some degree the families of the test species that will be selected. We will focus on neococcid 148

taxa including the Kerriidae, the family to which the target host belongs (see Fig. 1 and Gullan 149

and Cook 2007). Considering the phylogenetic relationships of scale insect families (Fig. 1), 150

we will aim to test one species in the Kerriidae, Paratachardina pseudolobata, which is also 151

invasive on Christmas Island (Table 2), and more than one species from the Coccidae. Species 152

in the Diaspididae will also be considered as a less closely related group of scale insects. Early 153

in the host testing process, an ‘out-group’ (test species phylogenetically more distant) will 154

also be used, most likely selected from the Pseudococcidae (Fig. 1). 155

As mentioned above, availability will determine species selection to some degree but in some 156

of the groups (e.g. Coccidae) there may be a number of species available. Species that can be 157

reared in laboratory conditions would be preferred but carrying out tests in field conditions 158

should also be acceptable as long as the tests can be well controlled. 159

2.3 No-choice tests 160

In no-choice tests, only the non-target test species will be provided to the parasitoid in the 161

experimental replicates. This is the most stringent test method that places the parasitoid 162

under high “oviposition pressure”. 163

For each test species, trials will be replicated 10 times. Each replicate will consist of 1) one 164

experimental cage with the test species (50 individuals in three different age groups/instars; 165

150 individuals in total) exposed to 10 female and 10 male parasitoids, 2) one positive control 166

cage consisting of 50 mature female T. aurantiaca exposed to 5 female and 5 male parasitoids 167

in order to confirm that the parasitoids used in the experiment are of good quality and 168

capable of parasitism in the given exposure time, and 3) one negative control cage which will 169

be similar to the experimental cage except the test species will not be exposed to parasitoids. 170

The negative controls will be used to determine any effect of parasitoid exposure on insect 171

mortality other than successful parasitization such as probing, host feeding and oviposition 172

without successful parasitoid development. 173

The cages will consist of fine mesh bags (sleeves) fixed on the branches of plants that serve as 174

host plants for the scale insects. Parasitoids will be collected from a lab colony and 175

introduced to the cages < 24 h after emergence. Exposure time to parasitoids will be 176

determined during preliminary studies to determine the optimal time frame for mating, egg 177

maturation and oviposition by the parasitoid. 178

Evaluation: 179

1) If the positive control does not yield any parasitoid emergence, the replicate will not be 180

evaluated (failed replicate). 181

2) If the positive control yields parasitoid emergence the replicate will be evaluated. The 182

parasitization rate in the positive will be noted but will not be compared to parasitization 183

rates in the test replicate. 184

6

3) Parasitoid emergence in the test replicate will be noted along with the approximate age 185

and developmental stage of the individuals yielding parasitoid emergence. These 186

individuals will not be used to compare mortality rates due to reasons other than 187

successful parasitism. 188

4) Mortality of test species in test replicates and negative controls will be noted. 189

Analysis: 190

1) If any test replicates yielded any number of parasitoid emergences, the test species will 191

be considered a suitable host. The level of suitability of the test species will not be 192

compared to the suitability of the target host at this stage of the project. 193

2) Mortality (except mortality due to successful parasitism) rates of test insects and insects 194

in the negative control will be compared using 2-sample t-tests. If the mortality rate is 195

significantly higher (α = 0.05), the test species will be considered susceptible and the 196

reasons for mortality will be investigated. 197

If a test species is susceptible (but not suitable), behavioural observations will be made to 198

determine the cause of the effect of parasitoid exposure. The observational arena will be a 199

‘window box’ arena. This arena is constructed by constructing a 10-cm W x 10-cm L x 5-cm H 200

box with one side being glass. The box is constructed so that it can be placed on the stem of a 201

potted host plant on which the test insects feed. Female parasitoids are then liberated inside 202

the box and the box closed. The potted plant then can be placed flat on its side and the box 203

positioned under a dissecting microscope. Video footage is then captured using a high 204

definition video camera with a microscope adaptor. The footage (4-6 h per observation) can 205

be analyzed later for the cause(s) of mortality (i.e. probing, host feeding, or oviposition 206

without full parasitoid development). If oviposition is suspected, dissections will also be 207

made to investigate parasitoid larval development. 208

2.4 Other testing methods 209

We considered using choice tests (where the parasitoid is presented with the test species and 210

the target host simultaneously) and sequential no-choice tests (where the parasitoid is 211

presented with the target host first then it is transferred on to the test species). However, in 212

our case these tests may have limited value for reasons given below. 213

A choice test would show whether a test species that is a suitable host in no-choice tests 214

would be consistently attacked when the target host is also available. A physiologically 215

suitable host may not be preferred over the target host and the assumption could be made 216

that parasitization would not occur (or at very low level) in field conditions. This test would 217

be used in cases where the suitable host (found suitable in a no-choice test) is of concern, e.g. 218

a beneficial or endemic non-target species that coexists with the target host. However, this 219

situation does not arise on Christmas Island where all known scale insects are non-native and 220

none of them are beneficial. This test is further limited by the assumption that the test 221

7

species and the target host occupy the same space hence providing the parasitoid with a 222

choice. This would also not be the case on Christmas Island. 223

A sequential no-choice test would further show the unsuitability of a test species. The 224

parasitoid may be ‘motivated’ to attack the test species even if it did not attack it in a simple 225

no-choice test if the parasitoid is first allowed to initiate oviposition behavior and to gain 226

experience. This test may be even more stringent than the simple no-choice test and one 227

would consider using it in the case of a test species that is of great concern to further show 228

the unsuitability of the test species. This would again require a beneficial or endemic non-229

target species neither of which exists on Christmas Island. Furthermore, similar to the choice 230

test, this would assume either the coexistence or very close proximity of the test species and 231

the target host. 232

233

3. Options for the location for host-specificity testing 234

There are three options for the location where host specificity testing could be conducted: 1) 235

in quarantine containment at the release location (Christmas Island); 2) in quarantine 236

containment on mainland Australia; and 3) in the native geographical range of the biological 237

control agent where no containment would be necessary. 238

Option 1. Testing in containment at the release location (Christmas Island) 239

This option is the least attractive and involves increased risks and expenses. There is no 240

quarantine containment facility on Christmas Island, a remote oceanic island. The expense of 241

constructing such a facility to Quarantine Approved Premises Criteria (Quarantine Insectary 242

Level 2) for host-specificity testing of a single agent would be prohibitive. Even if there were 243

such a facility, in case of escape, the biological control agent would find an environment very 244

similar to its native range with its natural host T. aurantiaca in abundance. The benefits of 245

this option would include easy access to the natural host for the parasitoid colony and no 246

further travel if and when a release permit is obtained. 247

Option 2. Testing in containment on mainland Australia 248

While this option is more attractive than Option 1 above, it is still somewhat risky, and labour 249

and cost intensive. It brings few benefits. The biological control agent (parasitoid) would have 250

to be brought into containment along with its natural host (Tachardina aurantiaca). This 251

would pose the risk of not only a parasitoid escaping but also a potentially invasive, host-252

generalist scale insect (on Christmas Island, for example, at least 15 horticultural species are 253

attacked by T. aurantiaca, including three species of Citrus, Macadamia, Guava, Pomegranate, 254

Chili, Eggplant, Star fruit, and Soursop)(R.W. Pemberton and D.J. O’Dowd, unpublished 255

results). Using a containment facility in the temperate region of Australia could decrease 256

these risks. In case of quality control issues of the biological control agent due to ‘lab 257

selection,’ additional travel, collection, and importation of the biological control agent would 258

8

be necessary, further increasing costs. Natural host colony loss (which can easily happen due 259

to overexposure to the parasitoid agent, fungal infections, etc.) would necessitate multiple 260

importations of the natural host, which would once again significantly increase costs and risk. 261

Option 3. Testing in the native geographical range of the biological control agent with no 262

containment necessary 263

In our case, this option is the most attractive, most cost-effective, and least risky. There are 264

many benefits to study biological control agents and carry out host specificity studies in the 265

native geographical range of the agent. In our case, both the parasitoid and its natural host is 266

readily available from the wild in Malaysia which ensures good quality parasitoid and host 267

cultures. The risk factor would be zero as there would be no importation of any organisms. 268

Although obviously desirable, such studies in the native range are not common, in part 269

because of the lack of local research facilities, lack of skilled and reliable cooperators, or 270

sufficient time in what are sometimes difficult locations (Van Driesche et al. 2008). However, 271

scientific work is cost-effective in Malaysia compared to Options 1 and 2 and our network of 272

collaborators is well established (see Table B1, O’Dowd et al. 2012). Options 1 (test in 273

containment on Christmas Island) and 2 (test in containment on the Australian mainland) 274

offer no benefits over this option. We therefore suggest that host specificity testing is carried 275

out in the native range of the biological control agent. This option carries the least risk and is 276

consistent with Recommendation 2 in a review of biosecurity risks in biological control 277

commissioned by the Australian Government (Ferrar et al. 2004) that biological control 278

practitioners undertake host specificity testing in the native region before any importation. 279

280

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353

11

Table 1. Records of known host families and genera for the primary parasitoid 354

Tachardiaephagus (Encyrtidae). Taxonomy follows Prinsloo (1977). The biological control 355

agent under investigation, Tachardiaephagus somervillei, is in bold. As a genus, 356

Tachardiaephagus has an extremely broad geographic range. With the exception of one 357

probably erroneous host record in Africa (Prinsloo 1983), all Tachardiaephagus species appear 358

to be family specialists and restricted to the Kerriidae. For host genera, number of species 359

recorded as hosts is in parentheses. Based on Noyes (2012, Universal Chalcidoidea Database, 360

http://www.nhm.ac.uk/research-curation/research/projects/chalcidoids/database/), except 361

for records for T. somervillei and T. sarawakensis (Hayat et al. 2010; Green et al. 2012; R.W. 362

Pemberton, pers. comm.) 363

Parasitoid species Distribution Recorded hosts (all Kerriidae)

Tachardiaephagus

somervillei

India, Malaysia, Thailand Kerria spp. (4)1

Tachardina aurantiaca

Tachardina sp.2

T. sarawakensis Sarawak (East Malaysia) Tachardina aurantiaca

T. tachardiae Brunei, China, India, Indonesia,

Malaysia, Sri Lanka, Taiwan,

Vietnam, Azerbaijan

Kerria spp. (8)

Paratachardina lobata

T. similis Afrotropical, South Africa Tachardina sp. (1)

T. absonus Afrotropical, South Africa Tachardina spp. (2)

T. communis Afrotropical, South Africa Tachardina spp. (5)

T. gracilis Afrotropical, South Africa Tachardina sp. (1)

1In Noyes (2012) both Kerria and Laccifer species are listed as hosts. However, Scalenet (Ben-364

Dov et al. 2012) indicates that Laccifer is a synonym for Kerria, so we have synonymized these 365

records with Kerria species. 366

2 Probably T. aurantiaca, since it is the only known Tachardina species in Asia. 367

12

Table 2. Scale insects of Christmas Island. It is highly probable that all of these species, with broad host

plant ranges and geographic distributions, are non-native to Christmas Island and introduced following

human settlement. The target species, Tachardina aurantiaca, for biological control is in bold. Families

are arranged in increasing phylogenetic distance from the Kerriidae based on Gullan and Cook (2007).

All scale insect taxa are 'neococcids' except for Icerya purchasi ('archeococcid'). Taxonomy and

distributions from Ben-Dov et al. (2012), http://www.sel.barc.usda. gov/scalenet/scalenet.htm).

Family and Species1

Common Name Distribution

Kerriidae (lac scales) Paratachardina pseudolobata (Kondo & Gullan) Tachardina aurantiaca (Cockerell)

False lobate lac scale Yellow lac scale

Oriental, Nearctic, Neotropical Oriental

Coccidae (soft scales) Ceroplastes ceriferus (Fabricius) C. destructor Newstead Coccus celatus De Lotto C. hesperidium Linnaeus Milviscutulus mangiferae (Green) Parasaissetia nigra (Nietner)

Pulvinaria urbicola Cockerell P. psidii Maskell2 S. coffeae (Walker) Saissetia oleae (Olivier)

Indian wax scale White wax scale Green coffee scale Brown soft scale Mango shield scale Nigra scale Urbicola soft scale Green shield scale Black olive scale Hemispherical scale

Cosmopolitan Afrotropical, Australasia, Oriental Afrotropical, Australasia, Oriental Cosmopolitan Cosmopolitan Cosmopolitan Pantropical Cosmopolitan Pantropical Cosmopolitan

Diaspididae (armoured scales) Aspidiotus destructor (Signoret) Hemiberlesia palmae (Cockerell) Ischnaspis longirostris (Signoret) 2

Lindingaspis sp. Pseudaulacaspis pentagona (Targioni Tozzetti) Unaspis citri (Comstock)

Coconut scale Tropical palm scale Black thread scale -- White peach scale White louse scale

Cosmopolitan Cosmopolitan Cosmopolitan -- Cosmopolitan Cosmopolitan

Cerococcidae (ornate pit scales) Cerococcus indicus (Maskell)

Spiny brown coccid

Cosmopolitan

Pseudococcidae (mealybugs) Dysmicoccus finitimus Williams

Asian coconut mealybug

Australasia, Oriental

Ferrisia virgata (Cockerell) Nipaecoccus viridis (Newstead) Pseudococcus longispinus (Targioni Tozzetti)

Monophlebidae (giant scales) Icerya purchasi (Maskell)

Striped mealybug Spherical mealy bug Long-tailed mealy bug

Cottony cushion scale

Cosmopolitan Cosmopolitan Cosmopolitan

Cosmopolitan

1Records from Campbell (1968), CSIRO (1999), O'Dowd et al. (2003), Bellis et al. (2004), Abbott (2004), Woods and

Steiner (2012) and Neumann et al. (unpubl. results); 2Tentative identifications

13

Table 3. Endemic hemipteran species known from Christmas Island and primary parasitoids

(superfamily Chalcidoidea: family Encyrtidae) associated with the families represented by the

endemic species. The data were extracted from the Universal Chalcidoidea Database (Noyes

2012). The families Nogodonidae and Rhopalidae have no associated chalcidoid primary

parasitoids and therefore endemic species in these families on Christmas Island can most

likely be excluded from all further consideration. Cicadellidae and Delphacidae have the

highest diversity of chalcidoid primary parasitoids but have magnitudes lower diversity of

encyrtid primary parasitoids. These data suggest that the encyrtid primary parasitoids of

families with endemic species on Christmas Island appear to not have host range overlap with

taxa where the target lac scale is included and the host range separation is at the suborder

level suggesting very distant phylogenetic separation. During the database analysis, only

records with species-level chalcidoid identification were used. N/A indicates not applicable.

1 Xestocephalus izzardi is also reported from Palau in the western Pacific Ocean (Linnavuori 1975). Its

status as an endemic on Christmas Island is questionable. 2 Leptocoris subrufescens on Christmas Island has been classified to subspecies status (L. subrufescens

subrufescens,). Another subspecies (L. s. flava) is described from Yap, western Pacific Ocean (Göllner-

Scheiding 1980). More research is needed to resolve the taxonomic status of these two subspecies of

L. subrufescens.

Endemic species Family

No. chalcidoid associates of family

No. encyrtid 1o parasitoid species of

family

Suborder/Family host range of encyrtids parasitizing family

Xestocephalus Izzardi1

Cicadellidae 627 6 Auchenorrhyncha (Cicadellidae)

Oxypleura calypso

Cicadidae 35 0 N/A

Clovia eximia Cercopidae 71 4 Auchenorrhyncha (Cercopidae- Aphrophoridae)

Ugyops aristella Delphacidae 248 5 Auchenorrhyncha (Delphacidae- Cicadellidae)

Varcia flavicostalis

Salona oceanica

Nogodinidae 0 N/A N/A

Leptocoris subrufescens2

Rhopalidae 0 N/A N/A

14

Figure 1. Portion of a phylogram of the scale insects based on nucleotide sequencing of

nuclear 18S rRNA for 72 species of scale insects and 10 outgroup taxa (see Gullan and Cook

[2007] for details). Only the neococcoids (red) are shown here. For all families given here

(except the Kermesidae), Bayesian posterior probabilities (numerical values above branches)

are >90%. For a host test list, we will select species from those families given in bold. The

lac scales Kerriidae (bold and italics) is a sister family of the soft scales Coccidae, more

distant to the armoured scales Diaspididae, and even further removed from the mealybugs

Pseudococcidae.

Pseudococcidae

Coccidae

Kerriidae

Kermesidae

Diaspididae

Gondwanan clade

BSE clade

Asterolecaniidae

Acanthococcid group

Dactylopiidae

Comments and suggestions for host specificity testing protocol (Neumann et al. 2013) from 5 ad hoc reviewers

Dr. Bob Pemberton (USDA-ARS, Invasive Plant Research Laboratory, Ft. Lauderdale, Florida)

Leading proponent of safety in classical biological control of weeds and insects; development of biological control for insect pests and weeds, including the lobate lac scale, foreign exploration for natural enemies) You all have done an excellent job on your testing proposal! I have attached the reviewed doc which has only a few comments.

1. More information on T. somervillei. 2. Say that it attacks only attached females not the smaller attached males. 3. Some reviewers will be unfamiliar with the basic biologies of scales and parasitoids

so it would be helpful to describe the life history of your lac scale. Then what stages the parasitoid has been reared from, and if known, what stages are attacked.

4. If it is known what host plants that Tachardina aurantiaca was on when parasitized by T. somervillei and list some.

5. Say something about the phenologies of both the scale and parasitoid to indicate that they overlap or that both appear to have continuous populations because of the moist tropical conditions. This would suggest that there should by synchrony and climatic suitability on Christmas Island.

6. Indicate that there is no parasitism of the scale on Christmas Island but that it is common or usual in its native Malaysia. Give some parasitism rates found. More needs to be said about the potential of the parasitoid and probable establishment based on similarities of the native area and Christmas Island. This information helps justify the host range testing.

7. For the use of "suitable host" some people say "suitable laboratory host" or "potential host." Could use "suitable physiological host" (note: same comment made by Barbara Barratt).

8. Although you say containment would not be needed in Malaysia, a containment level that excludes hyperparasitoids is needed.

Dr. Barbara Barratt (Principal Scientist, AgResearch Invermay, Biocontrol, Biosecurity and Bioprocessing, Mosgiel, New Zealand) Leading researcher in host specificity testing of parasitoids, risk assessment for classical biological control, biocontrol in natural areas, and developed the BIREA for New Zealand Basically looks pretty good to me but I have posed one or two questions.

1. Line 11. What damage is caused by T. aurantiaca? 2. Line 42. Clarify "actual published erroneous records." 3. Line 64. Revise subheading so as to not prejudge phylogenetic status 4. Line 71. "They would seem to be a real long-shot!" 5. Line 132. Add Wapshere 1974 as reference for centrifugal testing. 6. Line 140. Clarify - this determines physiological host range as distinct from

ecological host range. 7. Line 154. Add "and the host plant of the target" to the issue of establishment and

maintenance of colonies of the parasitoid. 8. Line 198. Rationale for not comparing parasitization rates in the control to the test

replicate. 9. Line 206. Same issue as at Line 198. 10. Line 208. Clarify reasoning here. 11. Line 292. Are coccid and diaspidid non-target species you want going to be

available in Malaysia?

Dr Matthew Purcell (Director, USDA-ARS Australian Biological Control Laboratory, Brisbane) Leading researcher in classical biological control of weeds. I’ve gone through the document a few times and it seems bullet proof to me. Given the remote location of Christmas Island to Australia, and to anywhere else for that matter, the risks are very low. Given that you have looked thoroughly into the insect fauna of the Island and that no endemic scales exist, your host testing protocol is more than adequate and fully justified.

1. It may be appropriate to mention in the Preamble that host-specificity testing is recommended to be conducted in Malaysia.

2. In section 2, I think you should make it implicit that only scales are being tested. 3. In section 2.2, it may be best to explain why it is not possible to determine the

species of scale insects to be tested at this point in time. 4. In section 2.3, 2nd paragraph, mature adult females are obviously the preferred stage

for the parasitoid to attack. It may be worth discussing here or elsewhere a little about the biology of the host and its parasite, especially since most Encyrtidae attack immatures. This would be particularly useful information when evaluating the experimental procedure.

5. In section 2.3, Evaluation 1. It would be beneficial to explain why parasitization rate in the positive control will not be compared to parasitization in rates in the test replicate. Ditto for Evaluation 3.

Dr. Don Sands OAM (retired, CSIRO, Ecosystems Sciences, Brisbane, QLD) Leading researcher in the biological control of scale insects and biological control of weeds I could add very little to your thorough testing protocol - you covered it very well. I have attached a few thoughts and comments that might be included or considered.

1. A quarantine facility on Christmas Island should be adequate for needed studies of specificity. Adequate lighting allowing sunlight to enter through double-glass will minimise artefacts in parasitoid behaviour.

2. Light and cage materials may be important when host testing and breeding parasitoids in cages. Encyrtidae often use light, certain spectra, intensity & absorption as ovipositional stimuli and for host recognition. I recommend black cages be used, as now used for rearing parasitoids by USDA and elsewhere, to avoid false positives and negatives.

3. Host specificity testing of parasitoids. Based on indigenous Hemiptera species and parasitoid host range only a small precautionary list of non-targets species would appear to require testing. As exotic scales on Christmas Island would appear to be the closest relatives to the target lac, these could be easily included in preliminary tests.

4. Many encyrtid parasitoids behave differently to their arthropod hosts feeding on different plant hosts. Tachardiaephagus could be tested with scales attached to a small range of plants, particularly native species.

5. Retain vouchers from each original shipment of wasps and also second generation of lab. – reared wasps, and have permanent preserved samples of insects released on the island.

6. Choice tests (target and non-target in same cage) can give misleading information and incorrect results from the diffusing pheromones derived from host affecting non-target host identity.

7. Nursery & mass rearing parasitoids for distribution. Once approvals for release minimise the numbers of parasitoids and number of their generations, in the confinement of quarantine, to avoid lab-adaptation or bottle-necking (can happen in 4 generations).

8. Mass rearing post approval is best done in cages outside of quarantine and with hosts + parasitoids exposed to diurnal temperature fluctuations, to enhance climate pre-adaptation and maximise numbers of parasitoids for release.

9. Release of parasitised scales on live plants (or bouquets) is more effective than the release of adult parasitoids.

10. There may be unrecognised hyper-parasitoids on Christmas Island likely to attack the Tachardiaephagus after it is introduced – worth predicting this possibility in case it influences parasitoid efficiency.

11. Release methods and localities, post release and establishment monitoring might best be outlined and methods included (& for what period) in the protocol?

Dr Tim Haye (Research Scientist, Centre for Agricultural Bioscience International [CABI], Rue des Grillons 1, CH-2800, Delemont, Switzerland) Leading researcher on the biology and use of parasitoids in classical biological control of insect pests I think the approach you suggest is well done. For us here at CABI it is a common practise to test the parasitoids in their native range. I do this for all the European insects that got introduced to North America. As lab tests often overestimate the host range of parasitioids, you may consider to look at the ecological host range (field host range) of your biocontrol agent in Malaysia. I would just take some samples from sites where maybe your target and non-targets co-occur. This would back up your lab data in case you may get non-target parasitism. The chalcidoid data base is a good tool, but the host records are often not complete, so any additional field data would make a later petition for releases of the biocontrol agent much stronger. The only thing I would hesitate about in your test design is that you are planning to test groups of parasitoids instead of individual wasps. Is there a specific reason for this? When testing groups you may have competition of parasitoids which may negatively influence your test outcome. Is there much known on the biology of the wasps (fecundity, pre-oviposition period, longevity)? All these factors may influence the test outcome, but I assume most of this is not known?

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Referral of proposed action

Project title: Importation, rearing and release of Tachardiaephagus somervillei (Hymenoptera: Encyrtidae) as a biological control agent for the yellow lac scale Tachardina aurantiaca (Hemiptera: Kerriidae) on Christmas Island, Indian Ocean

1 Summary of proposed action NOTE: You must also attach a map/plan(s) showing the location and approximate boundaries of the area in which the project is to occur. Maps in A4 size are preferred. You must also attach a map(s)/plan(s) showing the location and boundaries of the project area in respect to any features identified in 3.1 & 3.2, as well as the extent of any freehold, leasehold or other tenure identified in 3.3(i). 1.1 Short description

Use 2 or 3 sentences to uniquely identify the proposed action and its location.

Supercolonies of the invasive yellow crazy ant Anoplolepis gracilipes (YCA) are a major and on-going threat to biodiversity values on Christmas Island, especially to red land crabs Gecarcoidea natalis and robber crabs Birgus latro. To date, the management of YCA supercolonies has depended on surveillance, monitoring and control using toxic bait (mostly fipronil), particularly through aerial baiting programs in 2002, 2009 and 2012. While this program has been very effective in suppressing YCA supercolonies and there are encouraging signs of recovery in many treated areas, new supercolonies continue to form. There is widespread concern for the sustainability of this program in terms of its expense, non-target impacts, and the resources it diverts from other conservation programs. Recent research conducted by La Trobe University, funded by the Director of National Parks and endorsed by the Christmas Island Crazy Ant Scientific Advisory Panel, indicates that long-term, sustainable suppression of YCA supercolonies could be achieved through the introduction of a host-specific biological control agent that would indirectly affect YCA by reducing carbohydrate supply provided by scale insects, a key resource implicated in supercolony dynamics. The yellow lac scale Tarchardina aurantiaca (Hemiptera, Kerriidae; hereafter Tachardina) is likely to be the single biggest contributor to the honeydew economy of YCA supercolonies across the island. This species, like all other scale insect species on the island, is not native to Christmas Island.

The proposed action is to import, rear and release on Christmas Island a key natural enemy of Tachardina, the parasitoid microhymenopteran wasp Tachardiaephagus somervillei (Hymenoptera, Encyrtidae; hereafter Tachardiaephagus) as a biological control agent for this scale insect. The expectation is that Tachardiaephagus should indirectly suppress supercolony formation by YCA by controlling its key scale insect mutualist.

1.2 Latitude and longitude Latitude and longitude details are used to accurately map the boundary of the proposed action. If these coordinates are inaccurate or insufficient it may delay the processing of your referral.

Latitude Longitude location point degrees minutes seconds degrees minutes seconds NE extreme -10 24 40 105 42 14 NW extreme -10 26 14 105 32 59 SW extreme -10 30 54 105 32 1.6 S extreme -10 34 41 105 39 53 E extreme -10 28 4 105 42 49

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1.3 Locality and property description Provide a brief physical description of the property on which the proposed action will take place and the project location (eg. proximity to major towns, or for off-shore projects, shortest distance to mainland).

The project will be carried out on Christmas Island, an Australian External Territory located in the northeastern Indian Ocean at 10° 25’S and 105° 40’E (Fig. 1a). The island is approximately 2600 km northwest of Perth and 360 km south of the western end of Java, Indonesia. The island covers 135 km2, of which approximately 85 km2 (64%) is National Park (Fig. 1b). The remaining area is unallocated Commonwealth Crown Land (18%); mine lease (15%) (leased by Phosphate Resources Limited from the Commonwealth) and committed land, including private dwellings (3%). The Park contains two Ramsar wetlands at The Dales and Hosnie’s Spring (Fig. 1b).

Christmas Island rises from the sea in a series of cliffs and terraces to a maximum elevation of 361 meters. The terraces are separated by slopes covered by loose and jagged limestone boulders, or by sheer cliffs (Fig. 1c). The interior of the island is a slightly undulating plateau, from 160-361 metres above sea level (Fig. 1d). About 75% of the island is covered by vegetation, mostly rain forest.

Figure 1. (a) Geographic location of Christmas Island in the north eastern Indian Ocean, (b) Christmas Island showing the National Park (green), unallocated crown land (yellow), Ramsar sites (Blue hatching) and phosphate mining leases (green stippling). The National Park and Unallocated Crown Land together show the extent of remaining rainforest on Christmas Island, (c) Christmas Island rises in a series of cliff and terraces to a maximum elevation of 361 m (d) the interior of the Island is a slightly undulating plateau, from 160-361 m above sea level.

(a) (b)

(c) (d)

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1.4 Size of the development footprint or work area (hectares)

YCA supercolonies have formed patchily in rainforest across the entire Island (Fig. 2). The intention is for the biological control agent to both control existing supercolonies and suppress the formation of new ones, by eventually colonising and establishing self-sustaining populations across the entire forested area from an initially small number of release points. Thus, the proposed action is forecast to occur over the entire forested area of the Christmas Island National Park and adjacent unallocated Crown Land, totalling c. 10,000 ha.

Figure 2. Composite map showing YCA Supercolonies treated with toxic bait between 2000-2012. This map effectively shows the extent of supercolony formation over the last twelve years.

1.5 Street address of the site

Christmas Island National Park, PO Box 867, Drumsite, Christmas Island, Indian Ocean, 6798.

Unallocated Crown Land, managed by the Commonwealth Department of Department of Regional Australia, Local Government and Sports (DRALGAS).

1.6 Lot description Describe the lot numbers and title description, if known.

N/A

1.7 Local Government Area and Council contact (if known) If the project is subject to local government planning approval, provide the name of the relevant council contact officer.

Although local government approval is not required for the proposed action, consultation will still occur. The relevant local government is the Shire of Christmas Island – Western Australia Local Government Association. CEO Kelvin Mathews.

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1.8 Time frame Specify the time frame in which the action will be taken including the estimated start date of construction/operation. Foreign exploration in Southeast Asia has already located Tachardina at sites across 1900 km in Malaysia, within its native range in Southeast Asia. Research on the biology of its main parasitoid Tachardiaephagus is already underway in Southeast Asia, principally at the Forest Research Institute of Malaysia in Kuala Lumpur and at Sarawak Forestry in Semenggoh, Sarawak (see O’Dowd et al. 2012, and Section 2.1 below). A preliminary draft for host specificity testing has been produced (see Attachment 1) and host specificity testing could be completed in Malaysia by June 2013. Coincident with these activities, rearing facilities for Tachardiaephagus will be constructed on Christmas Island (see Attachment 2). Tachardiaephagus will be imported to Christmas Island when both tasks are completed, and a population will be established under controlled laboratory conditions in the rearing facility. The first field releases are planned for mid-2014, and there will be multiple releases thereafter through 2015 and 2016.

1.9 Alternatives to proposed action Were any feasible alternatives to taking the proposed action (including not taking the action) considered but are not proposed?

No

Yes, you must also complete section 2.2

1.10 Alternative time frames etc Does the proposed action include alternative time frames, locations or activities?

No

Yes, you must also complete Section 2.3. For each alternative, location, time frame, or activity identified, you must also complete details in Sections 1.2-1.9, 2.4-2.7 and 3.3 (where relevant).

1.11 State assessment Is the action subject to a state or territory environmental impact assessment?

No

Yes, you must also complete Section 2.5 NOTE: As described in Section 2.4, the regulatory framework under which the introduction of a biological control agent to the external Australian territory of Christmas Island would be considered cannot yet be clearly identified. Therefore, the requirement for a formal state or territory environmental impact assessment is also unclear. The matters of greatest relevance in the assessment of this Referral are the host specificity of the proposed biological control agent, and the likelihood of off-target impacts on other scale insects or species of concern. These issues are addressed in Section 2.5 in lieu of a formal environmental impact assessment.

1.12 Component of larger action Is the proposed action a component of a larger action?

No

Yes, you must also complete Section 2.7

1.13 Related actions/proposals Is the proposed action related to other actions or proposals in the region (if known)?

No

Yes, provide details:

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1.14 Australian Government funding Has the person proposing to take the action received any Australian Government grant funding to undertake this project?

No

Yes, provide details: The research supporting the proposed action is being funded by DSEWPaC though the Director of National Parks to La Trobe University. One postdoctoral fellow has just finished a three-year project establishing the importance of liquid carbohydrate resources provided by scale insects for YCA supercolony formation (November 2009 – November 2012), while a second postdoctoral fellow has been working on research and survey for prospective biological control agents of Tachardina (June 2010 – June 2013). This postdoctoral researcher has spent considerable time in Southeast Asia. It is intended that DSEWPaC continue to fund La Trobe University through the host-specificity testing phase in Kuala Lumpur, and on to the importation, rearing and release phases on Christmas Island (July 2013 – July 2016).

1.15 Great Barrier Reef Marine Park Is the proposed action inside the Great Barrier Reef Marine Park?

No Yes, you must also complete Section 3.1 (h), 3.2 (e)

2 Detailed description of proposed action NOTE: It is important that the description is complete and includes all components and activities associated with the action. If certain related components are not intended to be included within the scope of the referral, this should be clearly explained in section 2.7. 2.1 Description of proposed action This should be a detailed description outlining all activities and aspects of the proposed action and should reference figures and/or attachments, as appropriate.

Background – Biology and Impacts. Anoplolepis gracilipes (the yellow crazy ant, YCA) is a ‘tramp’ species that has become invasive throughout the tropics (Wetterer 2005). The YCA is listed by the IUCN as one of the world’s 100 worst invasive species (Lowe et al. 2000), and was accidentally introduced to Christmas Island between 1915 and 1934 (O’Dowd et al. 1999). Because of its negative impacts on species, interactions and ecosystem processes, YCA is recognised as the most significant and pervasive threatening process affecting biodiversity on Christmas Island, reflected by the listing of the Loss of biodiversity and ecosystem integrity following invasion by the Yellow Crazy

Ant on Christmas Island, Indian Ocean as a Key Threatening Process under the EPBC Act 1999, and as identified in Threat abatement plan to reduce the impacts of tramp ants on biodiversity in Australia

and its territories (Commonwealth of Australia 2006). The control of this ant features prominently in many Recovery Plans for EPBC-Listed species on Christmas Island, and has been the focus of natural resource management activities on the island for more than a decade at the cost of millions of dollars.

The attribute that makes the YCA so problematic on Christmas Island and elsewhere is its capacity to form high-density, expansive ‘supercolonies’. Many tramp ant species form supercolonies, often defined using a combination of criteria including genetic relatedness,intraspecific behavioural interactions, and ant abundance. For example, the invasive argentine ant Linepithema humile is genetically uniform across most of its European range and is regarded as a single supercolony (Giraud et al. 2002), while intercontinental behavioural assays and analyses of cuticular hydrocarbons suggest this species may form a single supercolony spanning Australia, Europe, North

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America and Japan (Sunamura et al. 2009; Suhr et al. 2010). Although two distinct genotypes of YCA occur on Christmas Island, these co-occur at very small spatial scales (Thomas et al. 2010) and behavioural assays pairing individual ants from opposite ends of the island suggest that the population on Christmas Island behaves as a single supercolony (Abbott 2005). Nevertheless, YCA supercolonies on Christmas Island have always been defined in terms of very high ant densities. YCA occurs at many locations across the island in very low abundance with no obvious impact on biodiversity, but in 1989, and then again in late 1997, YCA was discovered in several locations at extremely high densities sufficient to extirpate local populations of the abundant red land crab Gecarcoidea natalis (O’Dowd et al. 1999, 2003). The red crab is a keystone species in rainforest on the island that controls patterns seedling recruitment and rates of litter breakdown and nutrient cycling (Green et al. 1997, 2008). Since then, the density at which YCA kills land crabs leading to understorey transformation has become the operational definition of ‘supercolony’ on Christmas Island. On the ground, the density of YCA in supercolonies can be extraordinary – up to several thousand per square meter (Abbott 2005). A systematic, island-wide survey in 2001 found multiple supercolonies ranging in area from tens to hundreds of hectares, totalling c. 2500 ha, or 25% of rainforest on the island (Green et al. 2004; Green and O’Dowd 2009). Since 2001, supercolonies have continued to form and/or reform and upwards of 5000 ha of rainforest have been treated with toxic bait to 2012.

The key trait that has allowed YCA to form high-density supercolonies is its ability to form mutualistic associations with honeydew-producing hemipterans, principally scale insects (O’Dowd et al. 2003; Abbott and Green 2007). The scale insects suck sap from trees and secrete carbohydrate-rich honeydew on which the ants feed. The ants provide sanitation services for the scale insects, removing honeydew that might otherwise build up and kill them either through asphyxiation or the growth of sooty moulds, but the ants may also provide limited protection for the scale insects from generalist natural enemies. Supercolony-level densities of YCA and outbreak-densities of several species of scale insects invariably co-occur, and in supercolonies high densities of ants can typically be seen ascending the boles of most trees to visit scale insects in the canopy. The gasters of descending ants are swollen with carbohydrate-rich honeydew that they will take back to the nest to be shared with non-forager conspecifics. Site-scale, manipulative experiments on Christmas Island have demonstrated a bi-directional, causal link between co-occuring high densities and ants and scale – the exclusion of ants using toxic bait leads to a dramatic decline in scale abundance (Abbott and Green 2007), while the prevention of access by ants to scale insects using tree bands leads to a dramatic decline in ant density (O’Dowd et al. 2012). The tree banding experiment especially is important as “proof of concept” that removing a key food resource for ants could lead to supercolony suppression. On Christmas Island YCA interacts with several species of honeydew-secreting scale insects including Tachardina aurantiaca, the principal target of the biocontrol program (see below).

The mutualism between YCA and scale insects has manifold negative impacts on species abundances, interactions among species, and forest structure. At the core of these impacts is the devastating effect of YCA on land crabs, especially red crabs. YCA sprays formic acid as a weapon both to subdue prey and in self-defence, and although the amount sprayed by individual ants is tiny, at supercolony densities the overall effect is overwhelming. YCA supercolonies reduce formerly high densities of red crabs (averaging c. 0.5 – 1.0 crabs m-2) to nil, deregulating seedling recruitment and litter dynamics and resulting in a thick, diverse understorey of seedlings and saplings with an almost permanent layer of leaf litter (O’Dowd et al. 2003). In forest dominated by red crabs, the understorey is sparse and dominated by a few crab-resistant species, and the forest floor is almost devoid of litter for much of the year (Green et al. 1997, 2008). These impacts are widespread. Based on the spatial extent of supercolony formation over the last 12 years, it is likely that YCA has extirpated at least 20 million red land crabs, or about 30% of the total population in areas where they have formed supercolonies.

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YCA has also caused declines in the density of red land crabs at sites where high-density supercolonies have never formed. About half of the red crab population migrates to the coast each year to complete breeding activities, and many YCA supercolonies have formed across the crabs’ traditional migration routes. Thus, significant numbers of migrating red crabs have been killed en

route to the coast over many years, never to return to the former home ranges. As a result, some areas of rainforest are practically devoid of red crabs even though YCA supercolonies have never occurred there, and the same processes of understorey transformation are in train there too. It is hard to gauge the severity and extent of this “ghosting” effect because pre-YCA invasion data on red crab densities are sparse, but is likely to be significant; Green et al. (2011) estimated that around 25% of rainforest may have been ghosted at some time in the last decade. The direct and indirect (ghosting) impacts of YCA supercolony formation have been so widespread since the late 1990s that just 28% of rainforest could still be considered as “intact” (no YCA supercolony formation, and unaffected by ghosting) by 2007 (Green et al. 2011).

In YCA supercolonies, scale insects themselves can have large negative impacts on their host plants. Especially vulnerable is the Tahitian Chestnut Inocarpus fagifer, a widespread canopy tree that hosts very high densities of Tachardina on its outer twigs and leaves. In supercolonies, seedlings, saplings and small trees all suffer extremely high mortality, and the canopies of large trees are much reduced through the dieback of fine twigs and branches (Green et al. 2001, O’Dowd et al. 2003, P. Green and D. O’Dowd, unpublished results). There is also evidence that fruit production is reduced in supercolonies. Excess honeydew that YCA does not harvest settles on leaves of all plant species and is colonised by sooty moulds, which probably interferes with photosynthesis and growth.

YCA may affect many of the island’s bird species through direct interference and through altered resource availability and habitat structure (Davis et al. 2008, Davis et al. 2009). The Christmas Island Emerald Dove Chalcophaps indica natalis is 9-14 times less abundant in ant-invaded forest, and because it forages on the forest floor, is probably vulnerable to direct predation by YCA. The nesting success and density of juvenile Christmas Island Thrushes Turdus poliocephalus erythropleurus is lower in supercolonies, where they also show altered foraging and reproductive behaviours. Furthermore, these birds alter their choice of tree species in which to build nests, with lower frequency on tree species that typically experience high densities of scale insects and ants. The density of foraging Christmas Island white-eye Zosterops natalis is higher in supercolonies, perhaps because scale insects (as prey) are more common there. It is possible that impacts of YCA on thrushes and white-eyes affect frugivory and seed dispersal on the island; assays with both real and model fruit showed handling rates to be more than two-fold lower in YCA supercolonies, and manipulative experiments showed this to be a direct consequence of the presence of ants. There is no evidence that YCA supercolony formation significantly affects the density of nesting success of Abbott’s Booby Papasula abbotti (P. Green, unpublished data), while the impact of YCA on other seabirds and on other land birds such as the goshawk and owl are unknown.

Several endemic vertebrate species, including the pipistrelle bat Pipistrellus murrayi and endemic reptiles have experienced precipitous declines over recent years, but the causes of the declines are opaque. In the case of the pipistrelle it is possible that YCA supercolony formation has contributed to the decline, either directly through predation of bats at roost sites or indirectly by eliminating red crabs and facilitating the expansion of predators such as giant centipedes Scolopendra subspinipes, wolf snakes Lycodon aulicus, cats and rats (Schulz and Lumsden 2004, Lumsden et al. 2007, Beeton et al. 2010). However, the decline of the pipistrelle was well in train before the rise of YCA supercolonies in the late 1990s. The endemic reptiles were similarly in decline long before YCA supercolonies became common, and the role of YCA in their decline is also uncertain (Smith et al. 2012).

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In addition to impacts on species of concern, supercolony formation by YCA has also led to an altered web of species interactions that facilitates the entry and spread of other invasive species. The best example of this is the entry and spread of the giant African landsnail Achatina fulica (GALS) in rainforest on the island. GALS was introduced to the island in the 1940s, and despite being a notoriously invasive species (Lowe et al. 2000), its distribution was for many decades limited to settled areas, abandoned mining fields and roadsides. Experiments showed that predation by red crabs excluded this invader from establishing in rainforest (Lake and O’Dowd 1991), but the extirpation of red crabs in YCA supercolonies, coupled with the ability of GALS to coexist alongside YCA in supercolonies, has permitted this snail to establish high densities in rainforest at many locations across the island (Green et al. 2011). The facilitation of GALS by YCA could be due to the creation of enemy-free space, augmented understorey resources, or both.

The rise of YCA supercolonies and the extirpation of red crabs have also affected the invasion dynamics of other non-native organisms. These effects encompass both inhibition and facilitation for a range of non-native ant and snail species (O’Dowd and Green 2010; P. Green and L. O’Loughlin, unpublished results), while invasion by several weeds including Capsicum frutescens, Carica

papaya, Cordia curassavica, and Muntingia calabura appears to be facilitated in areas affected by YCA supercolony formation (P. Green and D. O’Dowd, personal observations).

Background – Management. Given all the above, supercolony formation by YCA is considered a major and on-going threat to biodiversity values on Christmas Island. To date the management of YCA has depended on surveillance, monitoring, and control using toxic bait (Green and O’Dowd 2009, Boland et al. 2011). New supercolonies continue to form, and there is concern for the sustainability of this program in terms of its expense, non-target impacts, and the resources it diverts from other conservation programs. Further, this program can only ever be reactive, and it has not been able to find an effective solution to the difficult issue of the management of incipient supercolonies at an islandwide spatial scale (see section 2.2, below). There is widespread agreement that the development of a more cost-effective, sustainable alternative to the use of toxic bait is needed to manage the YCA invasion on Christmas Island.

For the last three years, La Trobe University researchers have been investigating the potential for supercolony suppression by the biocontrol of scale insects. These researchers presented a summary of their findings to the Crazy Ant Scientific Advisory Panel (CASAP), and independent group of scientists who provide advice to the Director of National Parks and Parks Australia on matters pertaining to the management of the YCA invasion. CASAP advice was formally sought on the veracity of the research findings, and on the proposal to import, rear and release a biological control agent(s) as an option for controlling YCA supercolony formation and spread. At a meeting in December 2012, CASAP assessed the scientific merit of the research conducted by La Trobe University as well as the feasibility and risks of introducing a biological agent to Christmas Island. CASAP members were convinced that the option of biological control was a viable and feasible option for controlling YCA, the risks to the island’s biodiversity were very low, and the risk of doing nothing outweighed the risk posed by the importation and release of a biological control agent. CASAP advised the DNP to proceed with the implementation phase of the biological control research (see Attachment 3).

Biological Control. Classical biological control works on the principle that in their area of origin, populations of native species are kept in check by their natural enemies (predators, parasites or pathogens). There is a large body of literature demonstrating that in many cases, species introduced outside of their native ranges become invasive because they have effectively left their enemies behind. This is known as the “Enemies Release Hypothesis”. The principle of classical biological control then is the converse: to re-establish population control over invasive species by first identifying and then importing a natural enemy – a biological control agent – from within the native

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range of the target organism. In all instances, this now involves selection and testing of biological control agents to verify narrow host ranges that minimize the risk of non-target impacts in the area of introduction.

Indirect Biocontrol for YCA on Christmas Island. Despite the diversity and significant ecological and economic impacts of invasive ants worldwide, they have proved to be an especially difficult target group for biological control. A program for the biocontrol of the Red Imported Fire Ant (Solenopsis invicta) using a parasitic fly and a protozoan disease as agents is currently under development in the southeastern United States, but no species of ants have yet been controlled in the field using biological control agents and principles. Instead, a novel solution for managing the YCA invasion is proposed; rather than targeting the ant itself, a key mutualist species that plays a significant role in sustaining YCA supercolonies at very high and ecologically damaging densities will be targeted instead. Long-term, sustainable suppression of YCA supercolonies could be achieved through the introduction of a biological control agent that would indirectly affect YCA by reducing carbohydrate supply provided by honeydew-producing scale insects, a key resource implicated in supercolony dynamics.

The Proposed Action. While several species of honeydew-producing scale insects are common in YCA supercolonies, the yellow lac scale Tarchardina aurantiaca (Hempitera, Kerriidae) is almost certainly the single biggest contributor to the honeydew economy of YCA supercolonies across the island (O’Dowd et al. 2012). This referral is a proposal to import, rear and release on Christmas Island a key natural enemy of this scale insect, the parasitoid microhymenopteran wasp Tachardiaephagus somervillei (Hymenoptera: Encyrtidae - hereafter Tachardiaephagus) as a biological control agent for Tachardina. The expectation is that Tachardiaephagus will indirectly suppress existing YCA supercolonies and arrest formation of new supercolonies by controlling its key scale insect mutualist.

The Proposed Biological Control Agent. Tachardiaephagus somervillei (Fig. 3) is the most promising agent for introduction and release on Christmas Island. It is one of several primary parasitoids that have been found to attack yellow lac scale during studies conducted within it native distribution in Malaysia (Table 1). This parasitoid

attacks Tachardina across a 1900-km range in Peninsular Malaysia and Malaysian Borneo is the most abundant natural enemy of Tachardina has a short life cycle compared to its host exhibits superparasitism (i.e., where multiple progeny emergence from a single host

individual) causes high rates of parasitism on Tachardina in the presence of tending ants, including the

yellow crazy ant (Fig. 4) can be reared under laboratory conditions.

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Figure 3. Tachardiaephagus somervillei, a primary parasite of the yellow lac scale Tachardina aurantiaca in Malaysia and Singapore (drawing from Narayanan 1962. Pests of lac in India. Pp. 90-113 in Mukhopadhyay, B and Muthana, MS (eds) A Monograph on Lac. Indian Lac Res. Institut. Nancum, Ranchi, India). A Master’s student at Universiti Sains in Malaysia has also successfully reared T. somervillei under laboratory conditions.

Figure 4. Parasitism of the yellow lac scale Tachardina aurantiaca in Malaysia. The image shows emergence holes of the parasitoid Tachardiaephagus sp. (Encyrtidae) in tests of an aggregate of old adult females of Tarchardina near Sandakan, Sabah, Malaysian Borneo. Yellow crazy ants (Anoplolepis gracilipes) tended Tachardina at this site. Superparasitism (i.e., where more than one progeny is produced per host individual) is frequent. The mean number of Tachardiaephagus somervillei emerging from each parasitized female Tachardina was 2.1 (range 1- 4, N = 30) and up to 5 emergences occurred from each female in Peninsular Malaysia. In contrast, parasitism of Tachardina on Christmas Island was nil; emergence holes were never seen in examination of over 11,000 females over two years (or over the past 15 years of observations of Tachardina on the island).

1 mm

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Table 1. Natural enemy assemblages of the yellow lac scale Tachardina aurantiaca on Christmas Island and in Malaysia. + = present, -- = absent. For associates of T. aurantiaca, primary parasitoids oviposit on or in a host and develop within, ultimately killing the host. Hyperparasitoids seek out hosts with primary parasites, oviposit, and develop within the primary parasitoid. Predators feed externally and consume multiple scales. On Christmas Island, search focused on seven areas and examined over 11,000 females and 2000 males of the yellow lac scale. In Malaysia, targeted search for T. aurantiaca on known host plants (e.g., Pongamia pinnata) was frequently used to locate T. aurantiaca. Because the yellow lac scale is so rare across Malaysia, fewer individuals were inspected for parasitization. To assess enemies, host plant twigs with aggregates of T. aurantiaca were first inspected, and then isolated so that emerging parasitoids could be collected for later identification. Individual females of T. aurantiaca were also isolated to collect emergent parasitoids and dissected to determine overall rates of parasitization. On Christmas Island, lac scale predators Eublemma sp. and ?Holcocera sp. were extremely rare.

Species (Family) Association with T. aurantiaca

Christmas Island Malaysia

Tachardiaephagus somervillei Mahdihassan (Encyrtidae) primary parasitoid -- +

T. sarawakensis Hayat et al. (Encyrtidae) primary parasitoid -- +

Coccophagus euxanthodes Hayat et al. (Aphelinidae) primary parasitoid -- +

C. tschirchii Mahdihassan (Aphelinidae) primary parasitoid -- +

Coccophagus sp. (Aphelinidae)1 primary parasitoid2 -- +

Promuscidea unfasciativentris Girault (Aphelinidae) hyperparasitoid -- +

Aprostocetus (syn. Tetrastichus) purpureus Cameron (Eulophidae)1 hyperparasitoid3 -- +

Marietta leopardina Motschulsky (Aphelinidae)

primary parasitoid4 + +

Eublemma sp. (Noctuidae) predator + +

?Holcocera sp. (Blastobasidae) predator + +

1Tentative identification; 2Attack male T. aurantiaca only; 3primary parasitoid of many Coccidae, Diaspididae, Kerriidae, Margarodidae, and Pseudococcidae but known as a hyperparasitoid of C. tschirchii and Tachardiaephagus sp.; 4On Christmas Island and in Malaysia, Marietta leopardina is known only to attack male T. aurantiaca. It has never been observed emerging from female T. aurantiaca. In Southeast Asia, it is also reported as a hyperparasitoid of primary parasitoids of a variety of scale insects.

Supporting Research. Key outcomes from the research conducted by La Trobe University on Christmas Island and in Southeast Asia over the last three years firmly support the concept of indirect biological control (O’Dowd et al. 2012). Briefly,

dietary manipulation experiments in the laboratory, together with studies of stable isotopes in the field, have established a causal link between sugar supply and the dynamics of YCA supercolonies

a large, controlled field experiment has demonstrated an 80% decline in YCA abundance within several weeks of them being denied access to scale insects in the canopies of rainforest trees

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while variable, the average contribution made by Tachardina to the honeydew economy of YCA supercolonies is estimated to be 70%

within its native range in Malaysia, Tachardina is rare and patchily distributed, associated with diverse natural enemies including at least five species of primary parasitoids, and suffers high parasitization rates – all attributes consistent with population regulation by natural enemies

host records of Tachardiaephagus somervillei, the most abundant parasitoid of Tachardina across its native range in Malaysia suggest that it is a specialist within the lac scale family, Kerriidae. There are no native lac scale insects on Christmas Island

Tachardiaephagus does not occur on Christmas Island and Tachardina is not currently under effective biological control from the few existing natural enemies.

there is a single ecotype of female Tachardina on Christmas Island, which has been morphologically and genetically matched to populations in Southeast Asia that show evidence of being under control from their primary parasitoids

Approval, Importation & Rearing, and Release & Monitoring of Tachardiaephagus Approval: Currently, there is some uncertainty about the appropriate regulatory framework under which a biological control agent might be considered for introduction to Christmas Island (see Section 2.4, below). However, the framework will almost certainly include host-specificity testing as a necessary precursor to release (Palmer et al. 2010). The purpose of these trials is to test the proposition that Tachardiaephagus is as narrowly specific as the host records suggest, and that the probability of non-target impacts on species of concern is extremely low.

Australia has had a long history of conducting host-specificity tests in the area of agent origin, and it has only been relatively recently that these tests have been conducted within Australia by bringing agents into quarantine facilities (Palmer et al. 2010). However, testing within the native range is still desirable because it is safe (no need to import the agent), and it also allows for the possibility of conducting field tests which are seen as more realistic than laboratory trials (Secord and Karieva 1996). In any case, there is no suitable quarantine facility on Christmas Island in which to test Tarchardiaephagus against potential local non-target species, and the cost of constructing one would be prohibitive. Alternatively, Tachardiaephagus could be imported into containment in Australia, but this poses some risk to native kerriid species in Australia, and would present formidable regulatory issues. Instead, host-specificity tests will be conducted within the native distribution of Tachardina aurantiaca at the Forest Research Institute of Malaysia, where La Trobe University has established a research laboratory with the assistance of local co-operators. It is proposed to use “centrifugal host range testing” as the guiding principle to assess the host range of the Tachardiaephagus (Kuhlmann et al 2006, Neumann et al. 2010). In this approach, species other than the known host of the biological control agent are tested with the most closely related species (least phylogenetic distance, and with close similarities in biology and ecology) tested first then less similar species thereafter (“centrifugal principle”). This is outlined in more detail in Attachment 1.

Importation & Rearing: Many parasitoids have their own insect natural enemies, known as hyperparasitoids (i.e. parasites of parasites). The importation of a hyperparasite of Tachardieaphagus is inimical to the successful suppression of YCA supercolonies, because it could compromise seriously the capacity of Tachardieaphagus to build up population densities sufficient to control Tachardina. For this reason, great care will be taken to implement standard agent rearing and sanitation techniques to ensure that the founding population of Tachardiaephagus from Malaysia is free of hyperparasitoids and pathogens before importation to Christmas Island.

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Importation of Tachardiaephagus to the island should conservatively be regarded as the point of release. A production facility will be built on Christmas Island to receive the founder population, and to mass-rear these insects for field-release. This facility will be designed to contain the parasitoids through the rearing phase. The facility will produce Tachardina host plants using existing nursery facilities, and their maintenance in a dedicated glasshouse/greenhouse for the mass rearing of agents. This population will require careful monitoring and maintenance to minimize the selection of laboratory-adapted insects, and to counter the possible susceptibility of Tachardiaephagus to the loss of population heterozygosity. Sex determination in microhymenoptera is usually haplodiploid – males are haploid, females diploid, and heterozygosity at a multi-allelic sex-determining locus is required for femaleness. Inbreeding can lead to a preponderance of homozygous diploids that will either be sterile males, or experience a very high rate of mortality. The infrastructure, personnel and logistic support required for this phase of the biological control program have been outlined in Attachment 2.

Release & Monitoring: Protocols will be developed to estimate the impact of Tachardiaephagus on Tachardina and on YCA densities, and criteria will be established to select the number and location of primary release sites and control points, establish the most appropriate timing of the releases according to local site variation in Tachardina phenology, and to determine the rate of spread of Tachardiaephagus from release points. It is premature to give precise details on most aspects of the release and monitoring phase because they will largely depend on the number of insects that can be reared in the production facility, and on the extent and location of YCA supercolonies at the time. 2.2 Alternatives to taking the proposed action

This should be a detailed description outlining any feasible alternatives to taking the proposed action (including not taking the action) that were considered but are not proposed (note, this is distinct from any proposed alternatives relating to location, time frames, or activities – see section 2.3).

There are two alternatives to taking the proposed action:

1. Do not take the proposed action. Not taking the proposed action will ensure the management of YCA supercolonies and the amelioration of their impacts will continue to rely on chemical control, mainly the toxicant fipronil. However, the use of fipronil is perpetually reactive, because it relies on continual surveillance, monitoring and control using toxic bait and considerable human resources to keep abreast of supercolony formation. Further, it has not been able to deal with incipient supercolonies where YCA densities are increasing but still not high enough for YCA to monopolise the bait, and thereby minimise non-target impacts. Despite no evidence for the bioaccumulation of fipronil or its metabolites in baited areas (CESAR Consultants 2011), there is still disquiet among all the stakeholders over its continued use but a grudging acceptance of the lack of alternatives (Beeton et al. 2010). For all of these reasons, business-as-usual baiting with fipronil is seen as unsustainable in the long term and is now being considered as a transitional measure until biocontrol can be developed as an alternative (EPBC Referral, Helicopter baiting of

the exotic yellow crazy Anoplolepis gracilipes supercolonies on Christmas Island, Indian Ocean, 2012).

2. Develop a biocontrol program for several species of soft scales common in YCA supercolonies, using parasitoids already present on Christmas Island. Coccophagus

ceroplastae (Hymenoptera: Aphelinidae) and Encyrtus infelix (Hymenoptera: Encyrtidae), both parasitoids of a variety of coccid scale insects, have been discovered on Christmas Island as part of the supporting research leading up to this referral (O’Dowd et al. 2012). Both were almost certainly introduced inadvertently to the island in the past with importation of plant material with host scale insects. Both species attack a wide variety of soft scales, including four that are important in YCA supercolonies: Coccus hesperidium, C. celatus, Saissetia oleae and S. coffeae.

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The difficult issues of foreign exploration, host-specificity testing and navigating regulatory frameworks have been obviated by the presence of these parasitoids on the Island. Experience with the efficacy of these agents in dealing with the outbreak of Pulvinaria urbicola on Christmas Island (Neumann et al. 2011) suggests that the current lack of control of soft scales in YCA supercolonies is a result of dispersal limitation of their parasitoids. Dispersal limitation could presumably be overcome by releasing these parasitoids at multiple sites and at multiple times across the island. However, soft scales are estimated to contribute on average just 30% to the honeydew economy of YCA supercolonies, so targeting them alone is less likely to achieve suppression of YCA supercolonies than targeting Tachardina. For this reason, the development of biological control for soft scales using parasitoids already present on the island should be considered as being complementary, rather than as an alternative, to biological control for Tachardina.

The goal of the proposed action is to achieve ecologically-effective, cost-effective, and self-sustaining suppression of YCA supercolonies through the importation of a biological control agent specifically for Tachardina. Using these criteria, Alternative 1 is not a viable option because it is not self-sustaining, and Alternative 2 is not a viable option by itself because it is unlikely to achieve supercolony suppression.

2.3 Alternative locations, time frames or activities that form part of the referred action If you have identified that the proposed action includes alternative time frames, locations or activities (in section 1.10) you must complete this section. Describe any alternatives related to the physical location of the action, time frames within which the action is to be taken and alternative methods or activities for undertaking the action. For each alternative location, time frame or activity identified, you must also complete (where relevant) the details in sections 1.2-1.9, 2.4-2.7, 3.3 and 4. Please note, if the action that you propose to take is determined to be a controlled action, any alternative locations, time frames or activities that are identified here may be subject to environmental assessment and a decision on whether to approve the alternative.

N/A 2.4 Context, planning framework and state/local government requirements Explain the context in which the action is proposed, including any relevant planning framework at the state and/or local government level (e.g. within scope of a management plan, planning initiative or policy framework). Describe any Commonwealth or state legislation or policies under which approvals are required or will be considered against.

Ecological Context. The Expert Working Group’s Final Report (Beeton et al. 2010) provides an ecosystem-wide context for the proposed action. The EWG’s terms of reference included an examination of all threats to Christmas Island’s ecology, biodiversity management and any other issues relating to conservation management of the island and its surrounds. The principal finding of the EWG was that the extremely high biodiversity values of Christmas Island are in a “parlous state” (p. 9), to the extent that Christmas Island and its surrounding seas should be considered for listing as a threatened ecological community under the EPBC Act 1999. Invasion and supercolony formation by YCA was identified as a major contributing factor, and Loss of biodiversity and ecosystem integrity

following invasion by the Yellow Crazy Ant (Anoplolepis gracilipes on Christmas Island, Indian Ocean has been listed as a Key Threatening Process under the EPBC Act since 2005. Numerous scientific publications and reports over more than a decade have documented the direct and indirect negative impacts of YCA supercolony formation on various aspects of the island’s ecology (O’Dowd et al. 1999; Green et al. 2001; Marr et al. 2003; O’Dowd et al. 2003; Davis et al. 2008, 2010; Green and O’Dowd 2009; O’Dowd and Green 2010; Green et al. 2011, Smith et al., unpublished results).

Planning Framework – The Yellow Crazy Ant Research & Control Program. This 10-year plan was developed by DNP/CINP and CASAP to map out the management of Yellow Crazy Ants from 2007 to 2017. The major objectives of the program include significantly reducing the impact of Yellow Crazy Ants on the biodiversity values of Christmas Island by removing all existing, and halting future, development of supercolonies through:

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a) development of more target-specific baits which can be used on a more regular and widespread basis.

b) moving the baiting control methodology to a predominantly aerial approach.

c) research and development of biological control agents to reduce the densities of scale insect mutualists, potentially reducing the main cause of YCA supercolony formation.

Part C of this ten-year plan was fully endorsed by two recommendations in the EWG Final Report (Beeton et al. 2010):

Recommendation 9: (High priority) The initial steps taken already to explore biological control of the introduced scale insects be accelerated and biological control trials be started as soon as possible.

Recommendation 29: (High priority) Fundamental investigations continue and be augmented by adaptive management and aspects of Integrated Pest Control experimental work to develop cost-effective methods to break the scale insect - Yellow Crazy Ant mutualistic dependence.

Regulatory Framework – Director of National Parks and the Christmas Island Management Plan. The EPBC Act 1999 outlines the responsibilities of the Director of National Parks (DNP) to protect, conserve and manage biological diversity in Commonwealth reserves. The EPBC Act Regulations provide for the conservation of biological diversity in Commonwealth areas.

The EPBC Act requires the Director of National Parks to prepare a management plan for the Park at all times after the first plan for managing the park comes into effect. The third management plan for Christmas Island National Park (2002 - 2009) ceased to be in operation in March 2009 and the fourth management plan is currently in draft (2012) but is likely to be in force in early to mid 2013, before any importation of a biological control agent would occur. Until the fourth Plan comes into operation the Park will be managed in accordance with Section 357 of the EPBC Act. Section 357(1) states:

While a management plan is not in operation for a Commonwealth Reserve, the Director must exercise the Director's powers and perform the Director's functions in relation to the reserve or to a zone of the reserve so as to manage the reserve in accordance with:

a) the Australian IUCN reserve management principles for the IUCN category to which the reserve or zone has most recently been assigned by:

i. a Proclamation made under Subdivision B; or ii. a management plan that was in operation for the reserve (but is no longer); and

b) if the Director holds land or seabed included in the reserve under lease - the Directors obligations under the lease.

The specific objectives of the draft Christmas Island Management Plan relevant to this referral are:

Landscape

4.1.1 Impacts on the values and integrity of the park’s landscape, including visitor experience values will be avoided or minimised.

4.1.7 If the landscape changes in ways that threaten landscape or ecosystem values or otherwise beyond levels of acceptable change, the Director, in consultation with relevant stakeholders, will identify further monitoring requirements and will decide whether protection, rehabilitation or adaptation measures can and will be implemented.

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Terrestrial vegetation 4.2.3 Subject to risk and required approvals including from the Australian Quarantine and Inspection Service, the Director may introduce, or issue a permit for the introduction of, non-native species for conservation purposes such as the biological control of invasive species

4.2.4 So far as practicable, implement multi-species recovery plans, and relevant threat abatement plans for listed threatened species.

Terrestrial animals

4.3.1 Determine priorities for actions to conserve native plant and animal species based on:

a) a species’ conservation or biodiversity value, with high priority placed on endemic, keystone and EPBC Act listed and threatened species, and the risks of taking no action

b) likelihood that proposed actions will have ecosystem or multiple species benefits

c) likelihood that proposed actions will achieve their conservation aims

d) cost benefits and effectiveness of implementing proposed actions.

4.3.2 If EPBC Act listed, endemic, keystone or otherwise threatened or significant species are in decline to a level that may threaten their conservation status, the Director will:

a) assess the likelihood of mitigating known threats and, if feasible, implement threat mitigation strategies

b) if threats are not known, seek to determine (so far as possible) the threats and appropriate mitigation measures

c) if threats are not known or not likely to be mitigated for some time, assess the feasibility and effectiveness of implementing interventionist programs, such as captive breeding, that have the long-term aim of conserving the species in their natural environment.

4.3.3 The Director may take actions concerning animal species, including species listed under Part 13 of the EPBC Act, that are otherwise prohibited by the EPBC Act or Regulations where they are necessary to implement this plan, or where they are otherwise necessary for preserving or protecting the park, protecting or conserving biodiversity, or protecting persons or property in the park.

4.3.4 So far as practicable implement, multi-species recovery plans, and relevant threat abatement plans for listed threatened species.

4.3.5 Implement and contribute to on-park and off-park actions for conserving ecosystems and native species, particularly EPBC Act listed and other threatened species including red crabs and other keystone species.

4.3.7 Assess and monitor threats to native species. This will include the risk of invasive species which are currently considered a low threat becoming a greater threat.

4.3.9 Continue to implement the crazy ant control program including monitoring the impact of crazy ants on red crabs and other native species.

Ramsar wetlands and other freshwater wetlands

4.4.1 Applicable policies and actions from this plan will be applied to managing The Dales and Hosnies Spring.

4.4.4 Monitor and maintain the ecological character of the Ramsar listed wetlands known as Hosnies Spring and The Dales. This may include mitigating the impacts of potential threats, such as invasive species and unmanaged visitor use.

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Research and monitoring

8.7.1 Research and monitoring will focus on conserving, managing or restoring the park’s and island’s natural heritage values.

8.7.2 The Director or permitted organisations or individuals may carry out research and monitoring actions concerning native species, including species listed under Part 13 of the EPBC Act.

8.7.3 Permits authorising research and monitoring may be issued for conservation focused research consistent with this plan and with the park’s IUCN category (see Section 3.1).

8.7.4 Persons carrying out research and monitoring in the park will be required to provide the Director with reports on their work in ways requested by the Director.

8.7.6 Where needed, seek independent scientific and other specialist advice, for example through relevant advisory groups, for conserving and managing natural heritage.

8.7.8 Conduct and/or support or encourage conservation management research, monitoring and studies that assist with conserving and managing the park’s and island’s natural heritage, particularly studies on:

a) landscape and ecosystem changes and threats including monitoring and management of biodiversity condition

b) restoration, recovery and adaptive management of ecosystems and their species including rehabilitated minesites and red crab migration routes/habitat

c) populations of threatened and otherwise significant species, including but not limited to seabirds and land crabs (particularly red and robber crabs) and, as needed, invasive species

d) identification, quantification and, as needed, management of threatening processes impacting on ecosystems and threatened species. Give priority to invasive species, including the indirect biological control of crazy ants and control of cats and rats

8.7.9 Where possible, provide support for suitably qualified research organisations or individuals conducting natural heritage research consistent with Section 8.7.8.

Regulatory Framework – Commonwealth or state legislation or policies under which approvals are required or will be considered against

Any regulatory framework under which the introduction of a biological control agent to Christmas Island would be conducted is currently unclear. However, the Biological Control Act 1984, indicates in Section 4(1) that the responsible Minister, by giving notice in the Gazette, can extend the Act to the external territory of Christmas Island (http://www.comlaw.gov.au/Details/C2008C00315). In the absence of this extension, there is no obvious regulatory framework applicable to these circumstances. For example, the advisory committees (Plant Health Committee [PHC] and the National Biosecurity Committee [NBC]) recommend approvals to the Primary Industry Standing Committee (PISC). A clear approvals process exists for nomination of a biological control target (the yellow lac scale Tachardina aurantiaca [Kerriidae], in this case), but as an external territory Christmas Island appears to be outside of the jurisdiction of both the PHC and NBC. Currently no member on the PHC represents this external island territory; and, even if there were, the island is not within the jurisdiction of the NBC, which approves recommendations made by the PHC.

Nevertheless, initial steps have been followed in the Biosecurity Guidelines for the Introduction of Exotic Biological Control Agents for the Control of Weeds and Plant Pests

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(http://www.daff.gov.au/ba/reviews/biological_control_agents/protocol_for_biological_control_agents).A nomination of the target species as a candidate for biological control has been produced (see Attachment 4); offshore research in Malaysia on prospective biological control agents is underway; and a rationale for host-specificity testing has been produced (Appendix 1). Approval would be sought to undertake host-specificity testing within the natural range of the biological control agent (Malaysia) rather than in containment on the Australian mainland.

It is intended that in the absence of a regulatory framework for introduction of an exotic biological control agent that is applicable to Christmas Island, this referral will act as a catalyst and help provide a basis for the relevant government agencies to identify, in a timely manner, a workable framework under which to consider import approval. 2.5 Environmental impact assessments under Commonwealth, state or territory legislation If you have identified that the proposed action will be or has been subject to a state or territory environmental impact statement (in section 1.11) you must complete this section. Describe any environmental assessment of the relevant impacts of the project that has been, is being, or will be carried out under state or territory legislation. Specify the type and nature of the assessment, the relevant legislation and the current status of any assessments or approvals. Where possible, provide contact details for the state/territory assessment contact officer. Describe or summarise any public consultation undertaken, or to be undertaken, during the assessment. Attach copies of relevant assessment documentation and outcomes of public consultations (if available). As described above, the regulatory framework under which the introduction of a biological control agent to Christmas Island would be considered cannot be clearly identified. Therefore, the requirement for a formal state or territory environmental impact assessment is also unclear but is considered unlikely, given that the import of exotic species (e.g. plants for propagation) may be permitted (and occurs) under existing biosecurity import arrangements. In lieu of a formal environmental impact assessment, the matters of greatest relevance in the assessment of this Referral are addressed; the host specificity of the proposed biological control agent, and the likelihood of off-target impacts on other scale insects or species of concern.

Host Specificity of Tachardiaephagus somervillei. Based on known host records, all Tachardiaephagus species have narrow host ranges and appear to be family specialists, known only to attack scale insects in the Kerriidae, the family to which the yellow lac scale belongs (Table 2; see also O’Dowd et al. 2012). Table 2. Records of known host families and genera for the primary parasitoid Tachardiaephagus (Encyrtidae). As a genus, Tachardiaephagus has an extremely broad geographic range. With the exception of one probably erroneous host record in Africa, all Tachardiaephagus species appear to be family specialists and restricted to the Kerriidae. For host genera, number of species recorded as hosts is in parentheses. Based on Noyes (2012, Universal Chalcidoidea Database, http://www.nhm.ac.uk/research-curation/research/projects/chalcidoids/database/), except for records for T. somervillei and T. sarawakensis (Hayat et al. 2010. Oriental Insects 44, 23; R.W. Pemberton, pers. comm.; this study)

Species Distribution Recorded hosts

Tachardiaephagus somervillei India, Malaysia, Thailand Kerriidae

Kerria spp. (4)

Tachardina aurantiaca

Tachardina sp. (1)

T. sarawakensis Sarawak

Kerriidae

Tachardina aurantiaca

T. tachardiae Brunei, China, India, Indonesia, Malaysia,

Sri Lanka, Taiwan, Vietnam, Azerbaijan

Kerriidae

Kerria spp. (6)

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Laccifer spp. (3)

Paratachardina lobata

T. similis Afrotropical,

South Africa

Kerriidae

Tachardina sp. (1)

Coccidae

?Ceroplastes eucleae1

T. absonus Afrotropical,

South Africa

Kerriidae

Tachardina spp. (2)

T. communis Afrotropical,

South Africa

Kerriidae

Tachardina spp. (5)

T. gracilis Afrotropical,

South Africa

Kerriidae

Tachardina sp. (1)

1This record is likely to be erroneous (see Prinsloo1983. Entomol. Mem. Dept. Agric. Rep. S. Afr. 60, 26). Scale insect diversity on Christmas Island. No native or endemic scale insect species have been discovered in 400 hours of search over two years of intensive and extensive searches for scale insect species on Christmas Island (O’Dowd et al. 2012). However, this effort did yield five additional exotic scale insect species previously unknown to the island (Table 3). Table 3. Scale insects of Christmas Island. It is highly probably that all of these species, with broad host plant ranges and geographic distributions, are exotic to Christmas Island and introduced following human settlement. The yellow lac scale, Tachardina aurantiaca (Kerriidae) and Coccidae (soft scales) are the primary honeydew suppliers to the yellow crazy ant. Scale insects in bold occur commonly in YCA supercolonies. Taxonomy and distribution from Ben-Dov et al. (2012, http://www.sel.barc.usda. gov/scalenet/scalenet.htm).

Family and Species

Common Name Distribution Honeydew Producer

Kerriidae (lac scales) Tachardina aurantiaca (Cockerell) *

Paratachardina pseudolobata (Kondo & Gullan)

Yellow lac scale False lobate lac scale

Oriental Oriental, Nearctic, Neotropical

Yes Yes2

Coccidae (soft scales) Coccus celatus De Lotto *C. hesperidium Linnaeus *Milviscutulus mangiferae (Green) *Ceroplastes ceriferus (Fabricius) *C. destructor Newstead Saissetia oleae (Olivier) *S. coffeae (Walker) **Parasaissetia nigra

1

**Pulvinaria urbicola Cockerell

**P. psidii

1

Green coffee scale Brown soft scale Mango shield scale Indian wax scale White wax scale Black olive scale Hemispherical scale Nigra scale Urbicola soft scale Green shield scale

Afrotropical, Australasia, Oriental Cosmopolitan Cosmopolitan Cosmopolitan Afrotropical, Australasia, Oriental Pantropical Cosmopolitan Cosmopolitan Pantropical Cosmopolitan

Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes

Monophlebidae (giant scales) Icerya purchasi (Maskell)

Cottony cushion scale

Cosmopolitan

Yes

Cerococcidae (ornate pit scales) **Cerococcus indicus (Maskell)

Spiny brown coccid

Cosmopolitan

Yes

Pseudococcidae (mealybugs) **Dysmicoccus finitimus Williams

**Ferrisia virgata (Cockerell)1

Asian coconut mealybug Striped mealybug

Australasia, Oriental Cosmopolitan

Yes Yes

Diaspididae (armoured scales) Aspidiotus destructor (Signoret) Pseudaulacaspis pentagona

Coconut scale White peach scale

Cosmopolitan Cosmopolitan

No No

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(Targioni Tozzetti) *Hemiberlesia palmae (Cockerell) *Lindingaspis sp. **Lepidosaphes sp.1

Tropical palm scale -- Oystershell scale

Cosmopolitan -- --

No No No

*Record added by Abbott (2004, PhD Thesis, Monash University); **Record added by Neumann et al. (unpublished results); 1Tentative identification; 2P. pseudolobata produces honeydew but ejects it instead of producing droplets that can be collected by ants (Howard 2010, Fl. Entomol. 93, 1). Likelihood of off-target impacts. All known scale insect species on the island are exotic/invasive, and the proposed biological control agent for Tachardina on Christmas Island appears to be a narrow family specialist (Kerriidae). After intensive survey, no scale insect species of concern have been found on the island, and the probability of any direct non-target effects on any scale insects is negligible. Further, given the co-evolved nature of host-parasitoid interactions, it is extremely unlikely that Tachardiaephagus, as a primary parasitoid wasp, will attack any native Christmas Island insects. Risk of off-target impacts will be addressed by conducting host-specificity tests within the native range of Tachardina in Malaysia where it is safest to conduct these tests. 2.6 Public consultation (including with Indigenous stakeholders) Your referral must include a description of any public consultation that has been, or is being, undertaken. Where Indigenous stakeholders are likely to be affected by your proposed action, your referral should describe any consultations undertaken with Indigenous stakeholders. Identify the relevant stakeholders and the status of consultations at the time of the referral. Where appropriate include copies of documents recording the outcomes of any consultations.

Christmas Island has never been settled by Indigenous peoples prior to European settlement.

The local community on Christmas Island is very knowledgeable about YCA and its ecological impacts because of public outreach initiatives (community meetings, information brochures and stakeholder meetings) carried out by the DNP and La Trobe University over a number of years The local community is also very aware of the need to suppress supercolonies using toxic bait, especially because of the high community profile of the issue generated by three helicopter baiting campaigns, and the recent (September 2012) ground baiting of YCA supercolonies behind the Kampong, a major residential area. The concept of a biological control program for the suppression of YCA supercolonies was first introduced to the community through public presentations and meetings in 2009. University researchers Green and O’Dowd gave repeat presentations at the Malay Club, Sports and Recreation Centre, the Chinese Literary Association, the Christmas Island District High School and to Phosphates Resources Limited, in an effort to inform a wide cross section of the community of the proposal. The proposal was welcomed insofar as it presents an alternative means of suppressing supercolonies. All community groups appreciated the potential risks of introducing another non-native species to Christmas Island, but were reassured that risk assessment and strict regulatory oversight would occur prior to any importation and release of any biological control agent. Further public meetings will be held closer to the time of importation and release.

In addition, several key island based stakeholders, especially the Department of Regional Australia, Local Government, Arts and Sport (DRALGAS) are aware of and support (in-principle) the biological control research. This is reflected in the Australian Government’s response (http://www.environment.gov.au/parks/publications/christmas/ewg-response.html) to the Expert Working Groups final report (Beeton et al. 2010), particularly recommendation nine that: “the initial steps taken already to explore biological control of the introduced scale insects be accelerated and biological control trials be started as soon as possible”.

2.7 A staged development or component of a larger project If you have identified that the proposed action is a component of a larger action (in section 1.12) you must complete this section. Provide information about the larger action and details of any interdependency between the stages/components and the larger action. You may also provide justification as to why you believe it is reasonable for the referred action to be

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considered separately from the larger proposal (eg. the referred action is ‘stand-alone’ and viable in its own right, there are separate responsibilities for component actions or approvals have been split in a similar way at the state or local government levels).

The proposed action is part of a larger program of integrated pest management designed to ameliorate the impacts of YCA invasion by suppressing supercolony formation (see section 2.4 above, Planning Framework). The current backbone of the program is surveillance and monitoring to detect and map supercolonies, followed by the use of toxic bait, distributed by hand on the ground or by helicopter, to suppress them. The bait is AntOff®, with the active ingredient Fipronil at 0.01 g kg-1 in a fishmeal protein matrix, broadcast at 4 kg ha-1. Several alternative chemical approaches, including different neurotoxins and insect growth regulators (IGRs), have also been trialled but so far without success. New trials using IGRs were commenced during the aerial baiting campaign of September 2012 but the outcome of those trials will not be known until early to mid-2013.

3 Description of environment & likely impacts

3.1 Matters of national environmental significance Describe the affected area and the likely impacts of the proposal, emphasising the relevant matters protected by the EPBC Act. Refer to relevant maps as appropriate. The interactive map tool can help determine whether matters of national environmental significance or other matters protected by the EPBC Act are likely to occur in your area of interest. Your assessment of likely impacts should refer to the following resources (available from the Department’s web site): specific values of individual World Heritage properties and National Heritage places and the ecological character of

Ramsar wetlands; profiles of relevant species/communities (where available), that will assist in the identification of whether there is likely

to be a significant impact on them if the proposal proceeds; Significant Impact Guidelines 1.1 – Matters of National Environmental Significance; and associated sectoral and species policy statements available on the web site, as relevant. Your assessment of likely impacts should consider whether a bioregional plan is relevant to your proposal. The Minister has prepared four marine bioregional plans (MBP) in accordance with section 176. It is likely that the MBP’s will be more commonly relevant where listed threatened species, listed migratory species or a Commonwealth marine area is considered. Note that even if your proposal will not be taken in a World Heritage area, Ramsar wetland, Commonwealth marine area, the Great Barrier Reef Marine Park or on Commonwealth land, it could still impact upon these areas (for example, through downstream impacts). Consideration of likely impacts should include both direct and indirect impacts.

3.1 (a) World Heritage Properties

Description

N/A. There are no World Heritage Properties on Christmas Island

Nature and extent of likely impact

Address any impacts on the World Heritage values of any World Heritage property.

N/A. There are no World Heritage Properties on Christmas Island

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3.1 (b) National Heritage Places

Description (from Draft Christmas Island National Park Management Plan, Commonwealth of Australia 2012).

Christmas Island is not listed as a National Heritage Place but is listed on the Commonwealth Heritage register for both natural and cultural reasons (Commonwealth of Australia 2012).

Christmas Island has a number of unique ecological characteristics, as well as other features common to other oceanic islands. Characteristics of Christmas Island’s ecosystems include: fewer species than comparable areas of land on continents or islands near continents but with a relatively higher proportion of endemic terrestrial species; evolutionary isolation for thousands or millions of years until recent human arrival; native species that have evolved with few competitors; and many species with small population sizes. These characteristics make the island’s ecosystems and species of high conservation value but also highly vulnerable to environmental change, particularly from invasive species, climate change, and habitat clearing, fragmentation and degradation.

Christmas Island also has nine cultural sites on the register. Eight of the nine sites are located within settled areas of the island, and the other site (South Point Settlement remains) is well away from settled areas. Nature and extent of likely impact

Address any impacts on the National Heritage values of any National Heritage place.

The likelihood of negative impacts on species of concern from the introduction of a biological control agent is rated as negligible (see Section 2.5); therefore, the likelihood of negative impacts on Commonwealth Heritage Places is also rated as negligible. The likelihood of negative impacts on cultural sites is nil.

3.1 (c) Wetlands of International Importance (declared Ramsar wetlands)

Description (extracted from the Draft Christmas Island National Park Management Plan, Commonwealth of Australia 2012)

The Dales (RS1225). The Dales Ramsar site includes a series of seven dales, three of which support permanent springs and four support intermittent streams. The Dales are surrounded predominantly by semi-deciduous forest. On the seaward side at the edge of the shore terrace there is a line of coastal shrubland which merges with sea cliffs and rocky marine shores. The site extends seaward 50 metres and includes part of a narrow, shallow, sloping reef. Mixed amongst the terrestrial and marine environments is a range of karst features, highly representative of the environment of Christmas Island. The combination of this variety of habitats and the presence of permanent surface water supports a wide diversity of endemic and threatened species.

The site hosts part of the annual red crab migration and provides critical habitat for blue crabs as well as other land crabs. The Dales supports a diverse community of tree species and epiphytes. At Hugh’s Dale, and in parts of Anderson Dale and Sydney’s Dale, there are mono-specific stands of Tahitian Chestnut, Inocarpus fagifer, and the rare epiphytic Ribbon Fern, Ophioglossum pendulum. The endemic Arenga Palm, Arenga listeri, and endemic Ridley’s Orchid, Brachypeza archytas, are common in The Dales. Terminalia catappa grows to an unusual size on Christmas Island and several large specimens occur in The Dales. A number of endemic fauna occur within The Dales including the Abbott’s Booby and several land bird species. The endemic freshwater fish, the Brown Gudgeon, Eleotris fusca, has also been recently sighted within The Dales.

Hosnies Spring (RS512). The Hosnies Spring Ramsar site is an area of permanent, shallow freshwater wetland, fed by a natural spring system located approximately 30 metres above sea level

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and 120 metres inland of the seaward cliff. The wetland is covered by a stand of mangroves including Bruguiera gymnorhiza and B. sexangula estimated to be 120,000 years old. The margins of the wetland are well defined, with limestone cliffs to the north and west and a sharp transition to hibiscus and pandanus to the south. The area that surrounds the wetland site is predominantly rainforest, characterised by a 20 to 30 metre tall canopy of evergreen and deciduous tree species such as Pisonia

grandis and Barringtonia racemosa and a conspicuous lack of herb and shrub layers. There is a narrow band of coastal scrub with hardy species such as Scaevola taccada at the seaward margin of the shore terrace, with an unvegetated area of limestone pinnacles at the top of the sea cliff. The cliff descends some 17 metres almost vertically to the rocky marine shore below. The site extends 50 metres seaward of the low water mark and includes areas of shallow coral reef.

Hosnies Spring is remarkable for a number of reasons. First, it is one the few permanent freshwater areas on Christmas Island. Second, the mangroves occur at an elevation not recorded anywhere else in the world. Third, the age of the mangrove stand is extraordinary and finally, the individual trees are very large. The site also supports endemic and other significant fauna species including land crabs (in particular red, robber and blue crabs), sea and land birds and the Christmas Island flying fox.

In 2010, Ecological Character Descriptions for The Dales and Hosnies Spring were prepared under the National Framework and Guidance for Describing the Ecological Character of Australia’s Ramsar Wetlands (Hale and Butcher 2010). These descriptions form a baseline reference to help monitor and maintain the ecological character of The Dales and Hosnies Spring.

Nature and extent of likely impact

Address any impacts on the ecological character of any Ramsar wetlands.

Because the biological control agent is a host-specific, parasitoid insect, there are no foreseeable negative impacts associated with its introduction on the conservation values of either Ramsar Wetland. It is anticipated that there will be positive impacts on Ramsar sites, because of the likely reduction of YCA densities at these sites.

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3.1 (d) Listed threatened species and ecological communities

Description

EPBC Act - Listed threatened species occurring in Christmas Island National Park

Common name Scientific name Status

MAMMALS

Christmas Island shrew Crocidura attenuata trichura EN

Humpback whale Megaptera novaeangliae VU

Christmas Island pipistrelle Pipistrellus murrayi CR

Maclear's rat Rattus macleari EX

Bulldog rat Rattus nativitatis EX

BIRDS

Abbott's booby Papasula abbotti EN

Christmas Island emerald dove Chalcophaps indica natalis EN

Christmas Island frigatebird Fregata andrewsi VU

Christmas Island goshawk Accipiter fasciatus natalis EN

Christmas Island hawk-owl Ninox natalis VU

Christmas Island thrush Turdus poliocephalus erythropleurus EN

REPTILES

Green turtle Chelonia mydas VU

Hawksbill turtle Eretmochelys imbricata VU

Tree gecko Lepidodactylus listeri VU

Pink blind snake Typhlops exocoeti VU

FISH

Whale shark Rhincodon typus VU

VASCULAR PLANTS

Christmas Island spleenwort Asplenium listeri CR

A fern Pneumatopteris truncata CR

A fern Tectaria devexa var. minor EN

EN: endangered; EX: extinct; CR: critically endangered; VU: vulnerable

Nature and extent of likely impact

Address any impacts on the members of any listened threatened species (except a conservation dependent species) or any threatened ecological community, or their habitat.

Because the proposed biological agent is a primary parasitoid of one particular family of introduced scale insects, there are no foreseeable negative impacts of its introduction on any EPBC-Listed species. It is anticipated that there will be positive impacts on any EPBC-Listed (terrestrial) species, because of the likely reduction of YCA densities in their habitats.

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3.1 (e) Listed migratory species

Description

There are 68 bird species classed as migratory (or vagrant) detected on Christmas Island and five marine species including reptiles, mammals and one fish (see table in section 3.1d) that are recognised by EPBC, JAMBA and/or CAMBA and the Bonn Convention.

Common name Scientific name

EPBC Act marine

EPBC Act migratory JAMBA CAMBA ROKAMBA BONN

MAMMALS

Humpback whale Megaptera novaeangliae

Long-snouted spinner dolphin

Stenella longirostris (E. tropical Pacific/SE Asian pops)

BIRDS

Abbott’s booby Papasula abbotti = Sula abbotti

Antarctic prion Pachyptila desolata

Australian pelican Pelecanus conspicillatus

Australian pratincole Stiltia isabella

Arctic jaeger Stercorarius parasiticus

Baillon’s crake Porzana pusilla

Barn swallow Hirundo rustica

Bar-tailed godwit Limosa lapponica

Black-winged stilt Himanotopus himanotopus

Brown booby Sula leucogaster

Brown goshawk Accipiter fasciatus

Bulwer’s petrel Bulweria bulwerii

Cattle egret Ardea ibis = Bubulcus ibis

Christmas Island frigatebird Fregata andrewsi

Common greenshank, greenshank Tringa nebularia

Common koel Eudynamys scolopacea

Common noddy Anous stolidus

Common sandpiper Actitis hypoleucos =Tringa hypoleucos

Common tern Sterna hirundo

Crested tern Sterna bergii

Curlew sandpiper Calidris ferruginea

Dollarbird Eurystomus orientalis

Eastern reef egret Egretta sacra

Fork-tailed swift Apus pacificus

Garganey Anas querquedula

Glossy ibis Plegadis falcinellus

Great egret Ardea alba = Egretta alba

Great frigatebird Fregata minor

Great knot Calidris tenuirostris

Great skua Catharacta skua

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Greater sand plover Charadrius leschenaultii

Grey phalarope Phalaropus fulicarius

Grey plover Pluvialis squaterola

Grey wagtail Motacilla cinerea

Grey-tailed tattler Heteroscelus brevipes

Least frigatebird Fregata ariel

Little curlew Numenius minutus

Little egret Egretta garzetta

Little ringed plover Charadrius dubius

Little tern Sterna albifrons

Malay night heron Gorsachius melanolophus

Marsh sandpiper, little greenshank Tringa stagnatilis

Mongolian plover = lesser sand plover Charadrius mongolus

Nankeen kestrel Falco cenchroides

Nankeen night heron Nycticorax caledonicus

Oriental cuckoo Cuculus saturatus

Oriental plover Charadrius veredus = C. asiaticus veredus

Oriental pratincole Glareola maldivarum

Oriental reed-warbler Acrocephalus orientalis Pacific (= lesser) golden plover Pluvialis fulva

Pallid cuckoo Cuculus pallidus Pied imperial-pigeon Ducula bicolor Pin-tailed snipe Gallinago stenura Red-footed booby Sula sula Red-necked phalarope Phalaropus lobatus Red-necked stint Calidris ruficollis Red-rumped swallow Hirundo daurica Red-tailed tropicbird Phaethon rubricauda

Richard’s pipit Anthus novaeseelandiae

Ruddy turnstone Arenaria interpres Sacred kingfisher Todiramphus sanctus

Sanderling Calidris alba = Crocethia alba

Sharp-tailed sandpiper Calidris acuminata Sooty tern Sterna fuscatai Swinhoe’s snipe Gallinago megala Terek sandpiper Xenus cinereus Tree martin Hirundo nigricans Wedge-tailed shearwater Puffinus pacificus Whimbrel Numenius phaeopus Whiskered tern Chlidonias hybridus White tern Gygis alba White-tailed tropicbird Phaethon lepturus White wagtail Motacilla alba White-bellied sea-eagle Haliaeetus leucogaster

White-throated needletail = Spine-tailed swift

Hirundapus caudacutus

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White-winged black tern Chlidonias leucopterus Wood sandpiper Tringa glareola Yellow wagtail Motacilla flava REPTILES Green turtle Chelonia mydas

Hawksbill turtle Eretmochelys imbricata

Yellow-bellied sea snake Pelamis platurus FISH Bluestripe pipefish Doryramphus excisus

Fijian pipefish Corythoichthys amplexus

Ornate ghost pipefish Solenostomus paradoxus

Redstripe pipefish Doryramphus baldwini

Reef-top pipefish Corythoichthys haematopterus

Robust ghost pipefish Solenostomus cyanopterus

Roughridge pipefish Cosmocampus banneri Schultz’s pipefish Corythoichthys schultzi Sculptured pipefish Choeroichthys sculptus

Short-bodied pipefish Choeroichthys brachysoma

Thorn-tailed pipefish = pygmy pipefish

Micrognathus brevirostris pygmaeus

Whale shark Rhincodon typus

Yellow-banded pipefish Corythoichthys flavofasciatus

JAMBA – Japan-Australia Migratory Bird Agreement; CAMBA – China-Australia Migratory Bird Agreement; ROKAMBA – Korea-Australia Migratory Bird Agreement; Bonn – Bonn Convention

Nature and extent of likely impact

Address any impacts on the members of any listed migratory species, or their habitat.

Because the proposed biological agent is a primary parasitoid with hosts within one particular family of introduced scale insects, there are no foreseeable negative impacts of its introduction on any listed migratory species. It is anticipated that there will be positive impacts on EPBC-Listed migratory (terrestrial) species, because of the likely reduction of YCA densities in their habitats.

3.1 (f) Commonwealth marine area (If the action is in the Commonwealth marine area, complete 3.2(c) instead. This section is for actions taken outside the Commonwealth marine area that may have impacts on that area.) Description

N/A. The proposed action will not be taken in a marine area that lies outside the Commonwealth marine area

Nature and extent of likely impact

Address any impacts on any part of the environment in the Commonwealth marine area.

N/A. The proposed action will not be taken in a marine area that lies outside the Commonwealth marine area

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3.1 (g) Commonwealth land (If the action is on Commonwealth land, complete 3.2(d) instead. This section is for actions taken outside Commonwealth land that may have impacts on that land.) Description If the action will affect Commonwealth land also describe the more general environment. The Policy Statement titled Significant Impact Guidelines 1.2 - Actions on, or impacting upon, Commonwealth land, and actions by Commonwealth agencies provides further details on the type of information needed. If applicable, identify any potential impacts from actions taken outside the Australian jurisdiction on the environment in a Commonwealth Heritage Place overseas.

N/A. The proposed action will not be taken in a terrestrial area that lies outside Commonwealth land

Nature and extent of likely impact

Address any impacts on any part of the environment in the Commonwealth land. Your assessment of impacts should refer to the Significant Impact Guidelines 1.2 - Actions on, or impacting upon, Commonwealth land, and actions by Commonwealth agencies and specifically address impacts on: ecosystems and their constituent parts, including people and communities; natural and physical resources; the qualities and characteristics of locations, places and areas; the heritage values of places; and the social, economic and cultural aspects of the above things.

N/A. The proposed action will not be taken in a terrestrial area that lies outside Commonwealth land

3.1 (h) The Great Barrier Reef Marine Park

Description

N/A. The proposed action will take place on Christmas Island, several thousand kilometres away from the GBRMP

Nature and extent of likely impact

Address any impacts on any part of the environment of the Great Barrier Reef Marine Park.

Note: If your action occurs in the Great Barrier Reef Marine Park you may also require permission under the Great Barrier Reef Marine Park Act 1975 (GBRMP Act). If so, section 37AB of the GBRMP Act provides that your referral under the EPBC Act is deemed to be an application under the GBRMP Act and Regulations for necessary permissions and a single integrated process will generally apply. Further information is available at www.gbrmpa.gov.au

N/A. The proposed action will take place on Christmas Island, several thousand kilometres away from the GBRMP

3.2 Nuclear actions, actions taken by the Commonwealth (or Commonwealth agency), actions taken in a Commonwealth marine area, actions taken on Commonwealth land, or actions taken in the Great Barrier Reef Marine Park

You must describe the nature and extent of likely impacts (both direct & indirect) on the whole environment if your project: is a nuclear action; will be taken by the Commonwealth or a Commonwealth agency; will be taken in a Commonwealth marine area; will be taken on Commonwealth land; or will be taken in the Great Barrier Reef marine Park. Your assessment of impacts should refer to the Significant Impact Guidelines 1.2 - Actions on, or impacting upon, Commonwealth land, and actions by Commonwealth agencies and specifically address impacts on: ecosystems and their constituent parts, including people and communities; natural and physical resources; the qualities and characteristics of locations, places and areas; the heritage values of places; and the social, economic and cultural aspects of the above things.

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3.2 (a) Is the proposed action a nuclear action?

No

Yes (provide details below)

If yes, nature & extent of likely impact on the whole environment

3.2 (b) Is the proposed action to be taken by the

Commonwealth or a Commonwealth agency?

No

Yes (provide details below)

If yes, nature & extent of likely impact on the whole environment

Researchers from La Trobe University will undertake the proposed action under contract to the Director of National Parks. As outlined in detail in Sections 2.5, 3.1(b-e) and Section 5, there are no foreseeable negative impacts on the environment.

3.2 (c) Is the proposed action to be taken in a

Commonwealth marine area?

No

Yes (provide details below)

If yes, nature & extent of likely impact on the whole environment (in addition to 3.1(f))

3.2 (d) Is the proposed action to be taken on Commonwealth land?

No

Yes (provide details below)

If yes, nature & extent of likely impact on the whole environment (in addition to 3.1(g))

As outlined in detail in Sections 2.5, 3.1(b-e) and Section 5, there are no foreseeable negative impacts on the environment.

3.2 (e) Is the proposed action to be taken in the

Great Barrier Reef Marine Park?

No

Yes (provide details below)

If yes, nature & extent of likely impact on the whole environment (in addition to 3.1(h))

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3.3 Other important features of the environment Provide a description of the project area and the affected area, including information about the following features (where relevant to the project area and/or affected area, and to the extent not otherwise addressed above). If at Section 2.3 you identified any alternative locations, time frames or activities for your proposed action, you must complete each of the details below (where relevant) for each alternative identified. 3.3 (a) Flora and fauna

Christmas Island’s isolation, climate and the influence of land crabs have resulted in the development of distinct tropical rainforest vegetation, including some species that have evolved to be taller and larger than examples of the same species found elsewhere.

There are approximately 213 native plant species on Christmas Island, of which 17 are endemic (Claussen 2005). Holmes and Holmes (2002) list six endangered species, three vulnerable species, thirty three rare species and eleven as poorly known. A number of these species are listed as threatened under the EPBC Act.

The island’s terrestrial fauna is dominated by ecologically important and diverse land crabs. Red crabs (Gecarcoidea natalis) are the most numerous, and they act as keystone species because by regulating seedling recruitment, they influence structure and species composition of the island’s rainforest vegetation (Green et al. 1997, 2008). Red crabs also regulate the entry and spread of some invasive species in rainforest on the island (Lake and O’Dowd 1991, Green et al. 2011). The island also supports the world’s largest remaining population of the Robber Crab, Birgus latro (Drew et al. 2010).

Christmas Island is classified an Endemic Bird Area by BirdLife International, with nine nesting varieties /species of seabirds and around 80,000 resident birds. More than 100 seabird species have been recorded, including two endemic seabird species and one endemic subspecies that breed on the island. The Abbott's Booby Papasula abbotti (Listed as Endangered), Christmas Island Frigate Bird Fregata andrewsi, and the Golden Bosun Phaethon lepturus fulvus only nest on Christmas Island. There are seven endemic land birds, including the threatened Christmas Island Hawk-owl Ninox natalis, Christmas Island Thrush Turdus poliocaphalus erythropleurus, Christmas Island Goshawk Accipiter fasciatus natalis, and Christmas Island Emerald Dove Chalcophaps indica natalis.

The island is also important for other terrestrial fauna species. Five of the six recorded native reptile species are endemic; the Blue-tailed Skink Cryptoblepharus egeriae, Lister’s Gecko Lepidodactylus

listeri, the Forest Skink Emoia nativitatis, the Giant Gecko Cyrtodactylus sadlieri, the Coastal Skink Emoia atrocostata, and the Christmas Island Blind Snake Typhlops exocoeti. Lister’s gecko and the Christmas Island Blind Snake are listed under the EPBC Act as vulnerable. The range and abundance of Blue-tailed Skinks, Forest Skinks, Costal Skinks and Lister’s Geckos have dramatically contracted over the past decade and all are currently on the brink of extinction in the wild (Smith et al. unpublished results).

Five native endemic mammals have been recorded. The Bulldog Rat Rattus nativitatus, and Maclear’s Rat Rattus macleari, are extinct and the Christmas Island Shrew, Crocidura attenuata

trichura, is likely to be extinct. Murray’s Pipistrelle Bat Pipistrellus murrayi was once widespread but is now presumed extinct (Beeton et al. 2010). Yellow Crazy Ants are considered a threat to both the Pipistrelle Bat (Schultz and Lumsden 2004) and the Christmas Island Shrew (Schultz 2004). 3.3 (b) Hydrology, including water flows

Most rainforest on Christmas Island occurs over ancient limestone reefs of marine origin, which sit perched on basaltic bedrock. The soils are extremely porous, and Christmas Island has little flowing water. The few streams and soaks occur on the eastern and western coasts of the island, where the interface of the limestone and basalt occurs above sea level.

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3.3 (c) Soil and Vegetation characteristics

The Christmas Island environment can be classified into 12 broad environments:

1) marine – ocean water, sand flats, caves, coral reefs and walls,

2) shoreline rock platforms,

3) beaches,

4) sea cliffs,

5) terrace forest,

6) shallow soil rainforest on the higher terraces,

7) limestone scree slopes and pinnacles, cliffs

8) deeper plateau and terrace soils rainforest,

9) mangrove forest,

10) perennially wet areas,

11) karst, comprising caves, overhangs, rock crevices, and sinkholes, and

12) mining field.

The biological control agent will be released at multiple locations in environments 5, 6 and 8, but will hopefully spread to 7, 9, 10 and 12 as well. 3.3 (d) Outstanding natural features

There are several mapped caves in karst environments on the island. These will not be affected by the introduction of a biological agent. 3.3 (e) Remnant native vegetation (from Draft Christmas Island Management Plan, Commonwealth of Australia 2012)

The island’s remoteness, climate and the influence of land crabs have resulted in the development of distinct tropical rainforest vegetation, including some species that have evolved to be taller and larger than examples of the same species found elsewhere.

There are at least 17 endemic plant species, including a rare fern Asplenium listeri, a tall treelike pandanus Pandanus elatus, and a palm Arenga listeri. There are also relict populations of mangrove species and cycads which have been left isolated by the island’s tectonic uplift. A number of these species are listed as threatened under the EPBC Act.

Many of the world’s tropical rainforests, particularly on islands in the Indian Ocean, the Pacific Ocean and South-East Asian regions, are under threat from human activities. This makes the park’s and the island’s rainforest ecosystems of increasingly significant conservation value.

Vegetation and species of significance will not be adversely affected by the introduction of the biological control agent.

3.3 (f) Gradient (or depth range if action is to be taken in a marine area)

N/A 3.3 (g) Current state of the environment Include information about the extent of erosion, whether the area is infested with weeds or feral animals and whether the area is covered by native vegetation or crops.

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N/A 3.3 (h) Commonwealth Heritage Places or other places recognised as having heritage values

As for Section 3.1b

3.3 (i) Indigenous heritage values

Christmas Island was never been settled by Indigenous peoples prior to European settlement.

3.3 (j) Other important or unique values of the environment Describe any other key features of the environment affected by, or in proximity to the proposed action (for example, any national parks, conservation reserves, wetlands of national significance etc).

As for Section 1.4

3.3 (k) Tenure of the action area (eg freehold, leasehold)

Commonwealth Land

3.3 (l) Existing land/marine uses of area

National Park and Crown Land

3.3 (m) Any proposed land/marine uses of area

There are no additional proposed land uses for the area

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4 Measures to avoid or reduce impacts Note: If you have identified alternatives in relation to location, time frames or activities for the proposed action at Section 2.3 you will need to complete this section in relation to each of the alternatives identified. Provide a description of measures that will be implemented to avoid, reduce, manage or offset any relevant impacts of the action. Include, if appropriate, any relevant reports or technical advice relating to the feasibility and effectiveness of the proposed measures. For any measures intended to avoid or mitigate significant impacts on matters protected under the EPBC Act, specify: what the measure is, how the measure is expected to be effective, and the time frame or workplan for the measure. Examples of relevant measures to avoid or reduce impacts may include the timing of works, avoidance of important habitat, specific design measures, or adoption of specific work practices. Provide information about the level of commitment by the person proposing to take the action to implement the proposed mitigation measures. For example, if the measures are preliminary suggestions only that have not been fully researched, or are dependent on a third party’s agreement (e.g. council or landowner), you should state that, that is the case. Note, the Australian Government Environment Minister may decide that a proposed action is not likely to have significant impacts on a protected matter, as long as the action is taken in a particular manner (section 77A of the EPBC Act). The particular manner of taking the action may avoid or reduce certain impacts, in such a way that those impacts will not be ‘significant’. More detail is provided on the Department’s web site. For the Minister to make such a decision (under section 77A), the proposed measures to avoid or reduce impacts must: clearly form part of the referred action (eg be identified in the referral and fall within the responsibility of the person

proposing to take the action), be must be clear, unambiguous, and provide certainty in relation to reducing or avoiding impacts on the matters

protected, and must be realistic and practical in terms of reporting, auditing and enforcement. More general commitments (eg preparation of management plans or monitoring) and measures aimed at providing environmental offsets, compensation or off-site benefits CANNOT be taken into account in making the initial decision about whether the proposal is likely to have a significant impact on a matter protected under the EPBC Act. (But those commitments may be relevant at the later assessment and approval stages, including the appropriate level of assessment, if your proposal proceeds to these stages).

Many parasitoid wasps are constrained by their evolution to be the enemies of a narrow range of hosts. In Section 2.5, it was demonstrated that the proposed biological control agent Tachardiaephagus somervillei is almost certainly a highly specialised enemy of scale insects in the family Kerriidae; all Tachardiaephagus species have a narrow host range and appear to be family specialists, known only to attack lac scale insects in the Kerriidae, the family to which the yellow lac scale Tachardina belongs (Table 2). Just two kerriid species occur on Christmas Island, the target Tachardina aurantiaca, and the false lobate lac scale Paratachardina pseudolobata. Both are introduced, exotic and invasive on Christmas Island. There is one host record of a closely related parasitoid Tachardiaephagus tachardiae from another Paratachardina species, P. lobata in India (Table 2). Even if the host range of Tachardiaephagus somervillei did extend to invasive Paratachardina on the island, this would have no negative consequences.

Based on the research conducted by La Trobe University the likelihood that Tachardiaephagus will have non-target impacts on any other species, including other scale insects, is considered remote. This view is supported by the Crazy Ant Scientific Advisory Panel (CASAP) (see Attachment 3). However, despite some spectacular successes elsewhere, the history of biocontrol has also been marred by a few failures when the biological control agent itself proved to be problematic. Most of these instances were not (unlike this proposal) based on pre-release research, involved the introduction of generalist or oligophagous predators prior to the establishment of regulatory frameworks for biological control introductions, or failed to consider the spread of the biological

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control agent beyond the target area. In most cases, once a biological control agent has been released there is usually little that can be done to avoid or reduce unintended impacts. Clearly, such situations are best avoided entirely by making as sure as possible that Tachardiaephagus is as narrowly specific as the host records suggest (Table 2). Host specificity testing is required by Australia under the Biological Control Act 1984. However, no such regulatory framework has been identified that is currently applicable to the external territory of Christmas Island (end of Section 2.4). In the interim, La Trobe University will continue with plans to conduct pre-importation host-specificity trials with the assistance of cooperators at the Forest Research Institute of Malaysia at Kuala Lumpur and at Sarawak Forestry in Semenggoh.

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5 Conclusion on the likelihood of significant impacts Identify whether or not you believe the action is a controlled action (ie. whether you think that significant impacts on the matters protected under Part 3 of the EPBC Act are likely) and the reasons why.

5.1 Do you THINK your proposed action is a controlled action?

No, complete section 5.2

Yes, complete section 5.3

5.2 Proposed action IS NOT a controlled action. Specify the key reasons why you think the proposed action is NOT LIKELY to have significant impacts on a matter protected under the EPBC Act.

The proposed biological control agent is almost certainly host-specific on one target invasive species

Non-target impacts, although highly unlikely, will almost certainly be restricted to one other exotic and invasive species, in the same subfamily as the target.

5.3 Proposed action IS a controlled action Type ‘x’ in the box for the matter(s) protected under the EPBC Act that you think are likely to be significantly impacted. (The ‘sections’ identified below are the relevant sections of the EPBC Act.) Matters likely to be impacted

World Heritage values (sections 12 and 15A)

National Heritage places (sections 15B and 15C)

Wetlands of international importance (sections 16 and 17B)

Listed threatened species and communities (sections 18 and 18A)

Listed migratory species (sections 20 and 20A)

Protection of the environment from nuclear actions (sections 21 and 22A)

Commonwealth marine environment (sections 23 and 24A)

Great Barrier Reef Marine Park (sections 24B and 24C)

Protection of the environment from actions involving Commonwealth land (sections 26 and 27A)

Protection of the environment from Commonwealth actions (section 28)

Commonwealth Heritage places overseas (sections 27B and 27C)

Specify the key reasons why you think the proposed action is likely to have a significant adverse impact on the matters identified above.

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6 Environmental record of the responsible party NOTE: If a decision is made that a proposal needs approval under the EPBC Act, the Environment Minister will also decide the assessment approach. The EPBC Regulations provide for the environmental history of the party proposing to take the action to be taken into account when deciding the assessment approach. Yes No 6.1 Does the party taking the action have a satisfactory record of responsible

environmental management?

Provide details

The Commonwealth Director of National Parks is the responsible party for this action. The DNP manages several Commonwealth reserves on behalf of the Australian Government, in accordance with the EPBC Act and relevant park Management Plans. These reserves include the Christmas Island National Park, and the World Heritage listed Kakadu and Uluru Kata-Tjuta National Parks.

On matters pertaining to the management of the YCA invasion on Christmas Island, the DNP considers advice from the Crazy Ant Scientific Advisory Panel, comprised of researchers with expertise in invasive species biology including invasive ants, expertise with the local Island environment, and expertise in policy development, implementation and ecosystem management.

The on-ground research and implementation of the biocontrol program will continue to be the responsibility of La Trobe University, funded by the DNP. The La Trobe team has a very long history of research on the island, and two members were part of the team with DNP/CINP that won the 2003 Banksia Award for environmental management.

6.2 Has either (a) the party proposing to take the action, or (b) if a permit has been applied for in relation to the action, the person making the application - ever been subject to any proceedings under a Commonwealth, State or Territory law for the protection of the environment or the conservation and sustainable use of natural resources?

If yes, provide details

6.3 If the party taking the action is a corporation, will the action be taken in accordance with the corporation’s environmental policy and planning framework?

N/A

If yes, provide details of environmental policy and planning framework

6.4 Has the party taking the action previously referred an action under the EPBC Act, or been responsible for undertaking an action referred under the EPBC Act?

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Provide name of proposal and EPBC reference number (if known)

Aerial baiting of Yellow Crazy Ant supercolonies;

(a) EPBC Referral 2002/722 (b) EPBC Referral 2009/5016 (c) EPBC Referral 2012/6438

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7 Information sources and attachments (For the information provided above)

7.1 References List the references used in preparing the referral. Highlight documents that are available to the public, including web references if relevant.

Abbott, K.L. (2004). Alien ant invasion on Christmas Island, Indian Ocean: The role of ant-scale associations in the dynamics of supercolonies of the yellow crazy ant, Anoplolepis gracilipes. Ph.D Thesis, Monash University, Melbourne, Australia. http://arrow.monash.edu.au/vital/access/manager/Repository/monash:6496 (accessed 21 January 2013)

Abbott, K.L. (2005). Supercolonies of the invasive yellow crazy ant, Anoplolepis gracilipes, on an oceanic island: forager activity patterns, density and biomass. Insectes Sociaux 52: 266–273.

Abbott, K.L and Green, P.T (2007). Collapse of an ant-scale mutualism in a rainforest on Christmas Island. Oikos 116: 1238-1246.

Beeton, B., Burbidge, A., Grigg, G., How, R., McKenzie, N., and Woinarski, J. (2010). Final Report of the Christmas Island Expert Working Group to Minister for the Environment, Heritage and the Arts. Canberra, A.C.T., Australia. http://www.environment.gov.au/parks/publications/christmas/final-report.html (accessed 21 January 2013)

Boland, C.R.J., Smith, M.J., Maple, D.J., Tiernan, B., Barr, R., Reeves, R., and Napier, F. (2011). Heli-baiting using low concentration fipronil to control invasive yellow crazy ant supercolonies on Christmas Island, Indian Ocean. Pp. 152-156 in Veitch, C.R., Clout, M.N., and Towns, D.R. (eds.). Island invasives: eradication and management. Proceedings of the International Conference on

Island Invasives. Gland, Switzerland: IUCN and Auckland, New Zealand. http://www.issg.org/pdf/publications/island_invasives/pdfhqprint/2boland.pdf (accessed 21 January 2013)

Butcher, R. and Hale, J. (2010). Ecological character description for The Dales Ramsar site. Unpublished report to the Department of the Environment, Water, Heritage and the Arts, Canberra, A.C.T., Australia. http://www.environment.gov.au/water/publications/environmental/wetlands/61-ecd.html (accessed 22 January 2013)

Centre for Environment Stress and Adaptation (2011). Monitoring of the 2009 aerial baiting of yellow crazy ants (Anoplolepis gracilipes) on non-target invertebrate fauna on Christmas Island. Unpublished Report for the Director of National Parks, Canberra, A.C.T., Australia. http://www.environment.gov.au/parks/publications/christmas/fipronil-report.html (accessed 22 January 2013)

Claussen, J. (2005). Native plants of Christmas Island. Flora of Australia, Supplementary Series 22. Australian Government Department of the Environment and Heritage, Australian Biological Resources Study. Canberra, A.C.T., Australia.

Commonwealth of Australia (2006). Threat Abatement Plan to Reduce the Impacts of Tramp Ants on Biodiversity in Australia and its Territories. Department of the Environment and Heritage, Canberra, A.C.T., Australia.

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http://www.environment.gov.au/biodiversity/threatened/publications/tap/trampants.html (accessed 21 January 2013)

Davis, N.E., O’Dowd, D.J., Green, P.T., and Mac Nally, R. (2008). Effects of alien ant invasion on abundance, behaviour, and reproductive success of endemic island birds. Conservation Biology 22: 1165-1176.

Davis, N.E., O'Dowd, D.J., Mac Nally, R., and Green, P.T. (2010). Invasive ants disrupt frugivory by endemic island birds. Biology Letters 6: 85-88.

Detto, T. and Tiernan, B. (2011). The 2011 island-wide survey report on Yellow Crazy Ants and Red Crabs. Unpublished report to Christmas Island National Park. Christmas Island.

Drew, M.M., Harzsch, S., Stensmyr, M., Erland, S., and Hansson, B.S. (2010). A review of the biology and ecology of the Robber Crab, Birgus latro (Linnaeus, 1767) (Anomura:Coenobitidae). Zoologischer Anzeiger 249: 45-67.

Giraud, T., Pedersen, J.S., and Keller, L. (2002). Evolution of supercolonies: the Argentine ants of southern Europe. Proceedings of the National Academy of Science USA 99: 6075–6079.

Green, P.T. Comport, S., and Slip, D. (2004). The management and control of the invasive alien crazy ant (Anoplolepis gracilipes) on Christmas Island, Indian Ocean: the aerial baiting campaign, September 2002. Unpublished final report to Environment Australia and the Crazy Ant Steering Committee.

Green, P.T. and O’Dowd, D.J. (2009). Management of invasive invertebrates: lessons from the management of an invasive alien ant. Pp. 153-172 in Clout, M.N. and Williams, P.A. (eds). Invasive Species Management: A Handbook of Principles and Techniques. Oxford University Press, Oxford.

Green, P.T., O’Dowd, D.J., Abbott, K.L., Jeffery, M., Retallick, K., and Mac Nally, R. (2011). Invasional meltdown: invader-invader mutualism facilitates a secondary invasion. Ecology 92: 1758-1768.

Green, P.T., O’Dowd, D.J., and Lake, P.S. (1997) Control of seedling recruitment by land crabs in rain forest on a remote oceanic island. Ecology 78: 2474-2486.

Green, P.T., O’Dowd, D.J., Lake, P.S. (2001). From resistance to meltdown: secondary invasion of an island rain forest. Pp. 451-455 in Ganeshaiah, K.N., Uma Shankar, R. and Bawa, K.S. (eds.). Tropical Ecosystems: Structure, Diversity and Human Welfare. Proceedings of the International Conference on Tropical Ecosystems, Bangalore, India. Oxford-IBH, New Delhi.

Green, P.T., O’Dowd D.J., and Lake, P.S. (2008). Recruitment dynamics in a rainforest seedling community: context-independent impact of a keystone consumer. Oecologia 156: 373-385.

Hale, J. and Butcher, R. (2010). Ecological Character Description for Hosnie’s Spring Ramsar Site. Unpublished report to the Department of the Environment, Water, Heritage and the Arts, Canberra, A.C.T., Australia. http://www.environment.gov.au/water/publications/environmental/wetlands/40-ecd.html (accessed 21 January 2013)

Holmes, J. and Holmes, G. (2002). Conservation status of the flora of Christmas Island, Indian Ocean. Unpublished report to Environment Australia/Parks Australia North. Glenn Holmes and Associates, Atherton, Queensland.

Kuhlmann, U., Schafner, U. and Mason, P.G. (2006). Selection of non-target species for host specificity testing. Pp. 15-37 in Bigler, F., Babendreier, D. and Kuhlmann, U. (eds.). Environmental

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Impact of Invertebrates for Biological Control of Arthropods: Methods and Risk Assessment. CABI Publishing, Delemont, Switzerland.

Lake, P.S. and O’Dowd, D.J. (1991). Red crabs in rainforest, Christmas Island: biotic resistance to invasion by an exotic snail. Oikos 62: 25-29.

Lowe, S. Browne, M., and Boudjelas, S. (2000). 100 of the world’s worst invasive alien species. Aliens 12: S1-S12. http://www.issg.org/database/species/search.asp?st=100ss (accessed 21 January 2013)

Lumsden, L. Schulz, M., Ashton, R., and Middleton, D. (2007). Investigation of the threats to the Christmas Island Pipistrelle. Unpublished report to the Department of Environment and Water Resources, Canberra, A.C.T., Australia. http::// http://ausbats.org.au/#/resources/4553704436 (accessed 21 January 2013)

Marr, R.M., O’Dowd, D.J., and Green, P.T (2003). Assessment of non-target impacts of Presto® 01 ant bait on litter invertebrates in Christmas Island National Park, Indian Ocean. Unpublished report to Parks Australia North, Darwin, NT.

Neumann, G., Follett, P.A., Hollingsworth, R.G., and de León, J. (2010). High host specificity in Encarsia diaspidicola (Hymenoptera: Aphelinidae), a biological control candidate against the white peach scale in Hawaii. Biological Control 54: 107-113.

Neumann, G., Green, P.T. and O’Dowd, D.J. (2011). First record of Pulvinaria urbicola (Hemiptera: Coccidae), a potentially damaging scale insect, on Christmas Island, Indian Ocean. Unpublished report to Parks Australia. http://www.environment.gov.au/parks/publications/christmas/pubs/pulvinaria-report-2011.docx (accessed 21 January 2013)

O’Dowd, D.J. and Green, P.T. (2000). Design and feasibility of an island-wide survey of the invasive alien ant Anoplolepis gracilipes and its impact on Christmas Island, Indian Ocean. Unpublished report to Parks Australia North, Darwin, NT.

O’Dowd, D.J. and Green, P.T. (2010). Invasional meltdown: do invasive ants facilitate secondary invasions? Pp. 271-272 in Lach, L., Parr, C. & Abbott, K. (eds.) Ant Ecology. Oxford University Press, Oxford.

O’Dowd, D.J. Green, P.T., & Lake, P.S. (2003). Invasional ‘meltdown’ on an oceanic island. Ecology

Letters 6: 812-817. http://wolfweb.unr.edu/~ldyer/classes/396/odowd.pdf (accessed 21 January 2013)

O’Dowd, D.J., Green, P.T., and Lake, P.S. (1999). Status, impact, and recommendations for research and management of exotic invasive ants in Christmas Island National Park. Unpublished report to Environment Australia, Canberra, A.C.T., Australia http://www.issg.org/database/species/reference_files/Christmas_Island_Report.pdf (accessed 21 January 2013).

O’Dowd, D.J., Green, P.T., Neumann, G., and Wittman, S. (2012). Executive summary: research and development for indirect biological control of the yellow crazy ant (Anoplolepis gracilipes) on Christmas Island, Indian Ocean. Unpublished report to the Director of National Parks and the Crazy Ant Scientific Advisory Panel, 27 pp.

Palmer, W.A., Heard, T.A., and Sheppard, A.W. (2010). A review of Australian classical biological control of weeds programs and research activities over the past 12 years. Biological Control 52: 271-287. https://docs.google.com/a/monash.edu/viewer?a=v&q=cache:0-

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K3mgvVy6oJ:northeast.landcarevic.net.au/oln/projects/soil-health-program/reference-documents/biocontrol-12-year-review/at_download/file+&hl=en&gl=au&pid=bl&srcid=ADGEESgGf1MZIbSjBgRLOJrC7PanstLsXFnzXToIee3sUdK7Dn6ilFKnFls9q89PVBlxOSUNgJKVCjUOAKMyOHG2WDsP2FkvkoWpsPpgoJUntwXSJ6gKs63DvfDQ2aotz4z4J67pwN5K&sig=AHIEtbTK8Q9OLsVwz8aVroMgFYlNViLokA (accessed 21 January 2013)

Schultz, M. (2004). National Recovery Plan for the Christmas Island Shrew Crocidura attenuata

trichura. Commonwealth of Australia, Canberra. http://www.environment.gov.au/biodiversity/threatened/publications/recovery/c-attenuata-trichura/index.html (accessed 21 January 2013)

Schulz, M. and Barker, C. (2008). A Terrestrial Reptile Survey of Christmas Island, May-June 2008. Unpublished report for Parks Australia North, Darwin, NT.

Schulz, M. and Lumsden, L.F. (2004). National Recovery Plan for the Christmas Island Pipistrelle

Pipistrellus murrayi. Commonwealth of Australia, Canberra. http://www.environment.gov.au/biodiversity/threatened/publications/recovery/p-murrayi/pubs/p-murrayi.pdf (accessed 21 January 2013)

Secord, D. and Karieva, P. (1996). Perils and pitfalls in the host specificity paradigm. BioScience 46: 448-453.

Smith, M.J., Boland, C.R.J., Maple, D.J., Scroggie, M., Tiernan B., and Napier. F. (unpublished results) The Christmas Island Red crab (Gecarcoidea natalis): temporal and spatial patterns in burrow counts.

Smith. M.J., Cogger, H., Tiernan, B., Maple, D., Boland, C., Napier, F., Detto, T., and Smith, P. (2012). An oceanic island reptile community under threat: the decline of reptiles on Christmas Island, Indian Ocean. Herpetological Conservation and Biology 7: 206-218.

Suhr, E.L., O’Dowd, D.J., Mackay, D.A., and McKechnie, S.W. (2011). Genetic structure, behaviour and invasion history of the Argentine ant in Australia. Evolutionary Applications 4: 471–484.

Sunamura, E., Espadaler, X., Sakamoto, H., Suzuki, S., Terayama, M. and Tatsuki, S. (2009). Intercontinental union of Argentine ants: behavioral relationships among introduced populations in Europe, North America, and Asia. Insectes Sociaux 56: 143–147.

Thomas, M.L., Becker, K., Abbott, K., and Feldhaar, H. (2010). Supercolony mosaics: two different invasions by the yellow crazy ant, Anoplolepis gracilipes, on Christmas Island, Indian Ocean. Biological Invasions 12: 677-687.

Wetterer, J.K. (2005). Worldwide distribution and potential spread of the long-legged ant, Anoplolepis

gracilipes (Hymenoptera: Formicidae). Sociobiology 45: 77-97.

7.2 Reliability and date of information For information in section 3 specify: source of the information; how recent the information is; how the reliability of the information was tested; and any uncertainties in the information.

Information sources: Full references are provided in Section 7.1 for the cited sources in Section 3. In addition, other information came from the Draft Christmas Island National Park Management Plan

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(Commonwealth of Australia 2012), the Environment Protection and Biodiversity Conservation Act 1999 (Cwth), and the List of Commonwealth National Heritage places.

Information age: The information varies in age from 1991 through to 2012.

Information reliability: Studies published in scientific journals have been through a process of peer review and thus can be considered reliable. Unpublished reports have not been through this process, but can be considered as reliable because their authors are recognized as knowledgeable experts. This referral draws heavily on an unpublished report to the Director of Parks and the Crazy Ant Scientific Advisory Panel (O’Dowd et al. 2012). This report contains unpublished research, and in order to protect the publication rights of its authors this research should not be available to the public alongside the referral. The research was, however, formally peer-reviewed and endorsed by CASAP on 12 December 2012 (Attachment 3).

Information uncertainties: Uncertainties about the implementation and outcomes of the proposed action have been detailed in sections 2.1, 2.2, 2.4 and 2.5.

7.3 Attachments Indicate the documents you have attached. All attachments must be less than two megabytes (2mb) so they can be published on the Department’s website. Attachments larger than two megabytes (2mb) may delay the processing of your referral.

attached Title of attachment(s)

You must attach

figures, maps or aerial photographs showing the project locality (section 1)

Included within the referral document

figures, maps or aerial photographs showing the location of the project in respect to any matters of national environmental significance or important features of the environments (section 3)

Included within the referral document

If relevant, attach

copies of any state or local government approvals and consent conditions (section 2.5)

copies of any completed assessments to meet state or local government approvals and outcomes of public consultations, if available (section 2.6)

copies of any flora and fauna investigations and surveys (section 3)

technical reports relevant to the assessment of impacts on protected matters that support the arguments and conclusions in the referral (section 3 and 4)

report(s) on any public consultations undertaken, including with Indigenous stakeholders (section 3)

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Other attachments Attachment 1. Indirect biological control of the yellow crazy ant on Christmas Island – host range testing of the proposed agent Tachardiaephagus

somervillei for the primary target Tachardina

aurantiaca. Attachment 2. Biological Control Implementation for Tachardina aurantiaca on Christmas Island. Attachment 3. CASAP advice to DNP on the feasibility of indirect biocontrol for the suppression of YCA supercolonies Attachment 4. Nomination of the Yellow lac scale as a biological control agent target

Environment Protection and Biodiversity Conservation Act 1999

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8 Contacts, signatures and declarations NOTE: Providing false or misleading information is an offence punishable on conviction by imprisonment and fine (s 489, EPBC Act). Under the EPBC Act a referral can only be made by: the person proposing to take the action (which can include a person acting on their behalf); or a Commonwealth, state or territory government, or agency that is aware of a proposal by a person to take an action,

and that has administrative responsibilities relating to the action1. Project title: Importation, rearing and release of Tachardiaephagus

somervillei (Hymenoptera: Encyrtidae) as a biological control agent for the yellow lac scale Tachardina aurantiaca (Hemiptera: Kerriidae) on Christmas Island, Indian Ocean

8.1 Person proposing to take action This is the individual, government agency or company that will be principally responsible for, or who will carry out, the proposed action. If the proposed action will be taken under a contract or other arrangement, this is:

the person for whose benefit the action will be taken; or the person who procured the contract or other arrangement and who will have principal control and

responsibility for the taking of the proposed action.

If the proposed action requires a permit under the Great Barrier Reef Marine Park Act2, this is the person requiring the grant of a GBRMP permission. The Minister may also request relevant additional information from this person. If further assessment and approval for the action is required, any approval which may be granted will be issued to the person proposing to take the action. This person will be responsible for complying with any conditions attached to the approval. If the Minister decides that further assessment and approval is required, the Minister must designate a person as a proponent of the action. The proponent is responsible for meeting the requirements of the EPBC Act during the assessment process. The proponent will generally be the person proposing to take the action3.

Name Peter Cochrane Title Commonwealth Director of National Parks. Organisation Director of National Parks (Christmas Island National Park) ACN / ABN (if applicable) 13 051 694 963 Postal address GPO Box 787 Canberra Act 2601

Telephone (02) 6274 2220 Email Peter.Cochrane@environment.gov.au Declaration

I declare that to the best of my knowledge the information I have given on, or attached to this form is complete, current and correct. I understand that giving false or misleading information is a serious offence.

1 If the proposed action is to be taken by a Commonwealth, state or territory government or agency, section 8.1 of this form should be completed. However, if the government or agency is aware of, and has administrative responsibilities relating to, a proposed action that is to be taken by another person which has not otherwise been referred, please contact the Referrals Business Entry Point (1800 803 772) to obtain an alternative contacts, signatures and declarations page. 2 If your referred action, or a component of it, is to be taken in the Great Barrier Reef Marine Park the Minister is required to provide a copy of your referral to the Great Barrier Reef Marine Park Authority (GBRMPA) (see section 73A, EPBC Act). For information about how the GBRMPA may use your information, see http://www.gbrmpa.gov.au/privacy/privacy_notice_for_permits. 3 If a person other than the person proposing to take action is to be nominated as the proponent, please contact the Referrals Business Entry Point (1800 803 772) to obtain an alternative contacts, signatures and declarations page.

Environment Protection and Biodiversity Conservation Act 1999

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I agree to be the proponent for this action. I acknowledge that I may be liable for fees related to my proposed action following the introduction of cost recovery under the EPBC Act.

Signature

Date 15 April 2013

8.2 Person preparing the referral information (if different from 8.1) Individual or organisation who has prepared the information contained in this referral form.

Name

1* - Drs Peter Green and Dennis O’Dowd 2* - Michael Misso

Title

1* - Senior Lecturer / Reader (retired) 2* - Manager, Christmas Island National Park

Organisation

1* - La Trobe University 2* - Parks Australia

ACN / ABN (if applicable)

1* - 64 804 735 113 2* - 13 051 694 963

Postal address

1* - Department of Botany, Biological Sciences Building 2 2* - Christmas Island National Park PO Box 867, Christmas Island, Indian Ocean.

Telephone

1* - 03 9479 3675 2* - 08 9168 8700

Email

1* - p.green@latrobe.edu.au 2* - Michael.Misso@environment.gov.au

Declaration I declare that to the best of my knowledge the information I have given on, or attached to this form is complete, current and correct. I understand that giving false or misleading information is a serious offence.

Signature

Date

8/4/2013

Environment Protection and Biodiversity Conservation Act 1999

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REFERRAL CHECKLIST NOTE: This checklist is to help ensure that all the relevant referral information has been provided. It is not a part of the referral form and does not need to be sent to the Department. HAVE YOU:

Completed all required sections of the referral form?

Included accurate coordinates (to allow the location of the proposed action to be mapped)?

Provided a map showing the location and approximate boundaries of the project area?

Provided a map/plan showing the location of the action in relation to any matters of NES?

Provided complete contact details and signed the form?

Provided copies of any documents referenced in the referral form?

Ensured that all attachments are less than two megabytes (2mb)?

Sent the referral to the Department (electronic and hard copy preferred)?

PART A - Identifying and Analysing Project Management Risks Division Parks Australia Project Title Research and development for indirect biological control of the yellow crazy

ant (Anoplolepis gracilipes) on Christmas Island (Indian Ocean)

Branch /Section Christmas Island National Park Project Goal To suppress yellow crazy ant supercolonies on Christmas Island by the introduction of a host-specific parasitoid of its lac scale mutualist, Tachardina aurantiaca Date 21/11/2013

NOTE: In the Risk Assessment matrix below, the Consequence of The Risk can be judged in terms of:

1. Financial Consequences. For example, should the biocontrol program not proceed, the Consequence is recurrent funding for a

business-as-usual approach to YCA management dependent on surveillance, monitoring and control by toxic bait. 2. Indirect Biodiversity Consequences, which arise not from the implementation of an action itself or from its failure, but from the

knock-on effect of not implementing that action, or of it failing. For example, should the biocontrol program not proceed, the Consequence is continued negative impacts on elements of Island biodiversity, from either YCA or non-target impacts associated with the use of toxic bait.

3. Direct Biodiversity Consequences, which are a direct result of implementing an action. For example, off-target impacts of the

biocontrol agent imported to the island would have Direct Biodiversity Consequences.

For Risk 1 (below), No further action on the Biocontrol Program, we have combined both Financial and Indirect Biodiversity considerations when judging the severity of the Consequences. For Risks 2 – 5, we judged severity for Direct Biodiversity Consequences only.

In the Risk Assessment below,

1 2 3 4 5 6 7

Risk Ref/ID

The Risk

(What Can Happen?)

Source

(How can this Happen?)

Consequence

(What will happen if the risk occurs?)

Like

lihoo

d

Con

sequ

ence

Risk Level

1

No further action is taken to progress the biocontrol research and development project

a. Funding is insufficient to continue

a. Business as usual – management of YCA supercolonies continues to be reactive. Formation of new supercolonies cannot be prevented, and can only be controlled after they form. Continuing impacts of supercolony formation on biodiversity, especially red crabs and robber crabs. Continuing financial investment in the human resources and infrastructure (toxic bait and helicopter) to detect, map and control supercolonies. Continuing non-target impacts of the toxin, especially on robber crabs

Possible

Major

High

b. Research does not support the concept of indirect biocontrol – YCA is not dependent on honeydew, or suitable Biocontrol Agents (BCAs) are not available

b. As above Unlikely Major Medium

1 2 3 4 5 6 7

Risk Ref/ID

The Risk

(What Can Happen?)

Source

(How can this Happen?)

Consequence

(What will happen if the risk occurs?)

Like

lihoo

d

Con

sequ

ence

Risk Level

2 The imported BCA is not as host specific as predicted

Insufficient knowledge of the host specificity of the BCA

a. Other scale insects; In addition to the target species Tachardina aurantiaca, the BCA parasitizes other species of scale insects on the Island. All known species are non-native.

Very Unlikely

Insignificant Minimal

b. Other arthropods, including endemic insects such as stick insects and butterflies

Very Unlikely

Major Low

3 There is an endemic or native scale insect in the Family Kerridae on Christmas Island that has not yet been discovered

Insufficient field survey effort The BCA will parasitize a native species of scale insect

Very Unlikely

Major Low

4 The BCA does not achieve island-wide population control of Tachardina aurantiaca to the low levels seen in Southeast Asia

a. The climate on Christmas Island is wrong for the BCA

a. The BCA will not establish Very Unlikely

Insignificant Minimal

b. The BCA is suited to parasitize an ecotype of Tachardina from one part of its native range, but a different ecotype occurs on

b. The BCA will not establish well on Christmas Island

Very Unlikely

Insignificant Minimal

1 2 3 4 5 6 7

Risk Ref/ID

The Risk

(What Can Happen?)

Source

(How can this Happen?)

Consequence

(What will happen if the risk occurs?)

Like

lihoo

d

Con

sequ

ence

Risk Level

Christmas Island

c. The BCA is a poor disperser, and cannot move much beyond its initial point of release

c. The BCA will only achieve local population control of Tachardina, at points of release

Very Unlikely

Insignificant Minimal

d. Tending of Tachardina by YCA reduces parasitization by BCA

d. The incidence of parasitization on Tachardina by the BCA will be low

Unlikely Insignificant Minimal

e. The BCA was infected with a hyperparasitoid at importation

e. The population densities of the BCA will never be high enough to achieve control Tachardina

Very Unlikely

Insignificant Minimal

f. Marietta leopardina, already present on Christmas Island, acts as a hyperparasitoid for the BCA once it is introduced

f. The population densities of the BCA will be too low to achieve control of the target

Possible Insignificant Low

1 2 3 4 5 6 7

Risk Ref/ID

The Risk

(What Can Happen?)

Source

(How can this Happen?)

Consequence

(What will happen if the risk occurs?)

Like

lihoo

d

Con

sequ

ence

Risk Level

5

The BCA does not reduce the incidence of supercolony formation

Despite a large contribution by Tachardina, there is sufficient honeydew contributed by soft scales to sustain existing supercolonies, and permit the formation of new ones.

Supercolonies continue to form across the island, requiring business as usual surveillance, monitoring and control using toxic bait and condsiderable human resources

Possible Insignificant Low

PART B – Risk Register & Corrective Strategies 1For justification of risk, see Executive Summary (ES)

Risk Short title Risk Level Justification for Likelihood & Consequences1

Options for Risk Mitigation

1a Insufficient funding High Christmas Island National Park Plan of Management Expert Working Group Final Report Reports and Publications by La Trobe University and Monash University

EA to provide sufficient funding for the Biocontrol Program

1b Negative research findings Medium ES A1-A4 ES B1-B5

None

2a Non-target scale insects Minimal ES B4 Pre-importation host specificity trials conducted under laboratory conditions in Malaysia.

2b Non-target other insects Low ES B4 Pre-importation host specificity trials conducted under laboratory conditions in Malaysia.

3 Undiscovered native/endemic scale insect

Low ES B2 None. Field surveys demonstrate to operational certainty there are no native or endemic scale insects on Christmas Island

4a Climate matching for the BCA Minimal ES B3 & B5 Select donor populations of the BCA from areas that match most closely the local climate on Christmas Island

4b Ecotype matching for Tachardina

Minimal ES B3 Select donor populations of the BCA from Tachardina hosts that match most closely the local type on Christmas Island

4c Dispersal Minimal ES B3 Create “propagule pressure” by releasing the BCA at multiple sites and multiple times across Christmas Island

4d Scale tending by YCA Minimal ES B4 & B5 Select donor populations of the BCA from sites where Tachardina is tended by high densities of mutualistic ants, especially Anoplolepis gracilipes

4e Hyperparasitism of the BCA Minimal ES B4 Use standard laboratory rearing techniques to ensure the BCA is free of any hyperparasitoids prior to its importation to Christmas Island

4f Marietta acts as a hyperparasitoid of BCA

Low ES B4 None. However, there is no evidence of that Marietta attacks female Tachardina, either as a primary parasitioid or in order to attack the larvae of other primary parasitoids inside female Tachardina.

5 Biocontrol of Tachardina insufficient to suppress YCA supercolonies

Low ES A4 Develop and implement a biocontrol program for soft scale insects on Christmas Island to complement the program under development for Tachardina. Coccophagus ceroplastes and Encyrtis inflelix, both parasitoids of coccid scale insects, already occur on Christmas Island. Their rearing and release would not require a referral under the EPBC Act.