Conférence ANSES

March 10, 2016

What is the risk of

X. fastidiosa for

Europe?

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On 21 October 2013 Italy reported to the European Commission and the other EU Member States the occurrence of Xylella fastidiosa in its territory, in the Apulia Region (Lecce Province);

This was the first report of an outbreak of Xylella fastidiosa under field conditions in the EU;

Suspected infected area was around 8000 ha (approximately 600.000 trees) and 1000 ha was severely affected leading in most cases to death of trees;

BACKGROUND OF XYLELLA FASTIDIOSA OUTBREAK

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DISEASE SYMPTOMS ON OLIVE

Courtesy of Donato Boscia

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PREDICTING RISK – A CHALLENGE !

The risk posed by Xylella fastidiosa in Europe

https://nl.wikipedia.org/wiki/Pythia

The challenge To propose a RISK ASSESSMENT for an unknown disease, with a pathogen not previously reported in Europe and just recently detected Need for data Several research lines requested Host range, teledetection data, …

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Known hosts (many cultivated and spontaneous plants common in Europe), but a range of European wild plant species would meet Xylella for the first time.

All xylem-fluid feeding insects in Europe should be regarded as potential vectors of X. fastidiosa.

The only route for natural spread of X. fastidiosa is by insect vectors that generally fly short distances up to 100 metres, but can be transported by wind over long distance.

http://www.efsa.europa.eu/en/efsajournal/pub/3468

NOVEMBER 2013

Statement of EFSA on host plants, entry and spread pathways and risk reduction options for Xylella fastidiosa Wells et al. (Nov. 2013)

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Prepare a risk assessment of X. fastidiosa and its insect vectors for the EU territory;

Identify risk reduction options and evaluate their effectiveness in reducing the risk;

Evaluate the EU phytosanitary requirements against these organisms, in Council Directive 2000/29/EC and in the EU emergency legislation.

Take into account data on X. fastidiosa that will be produced in the current EU outbreak area (particularly relevant for the evaluation and fine-tuning of EU measures against Xylella fastidiosa)

XYLELLA FASTIDIOSA PEST RISK ASSESSMENT

In addition to the 2013 Statement, EFSA was requested to

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EFSA PLH PANEL WORKING GROUP ON XYLELLA FASTIDIOSA PEST RISK ASSESSMENT 2013-2014

WG members

Claude Bragard (Chair)

Jean Claude Gregoire

Domenico Bosco

David Caffier

Rodrigo Almeida

Stephen Parnell

Hearing experts

Donato Boscia

Maria Saponari

EFSA Staff Gabor Hollo Ewelina Czwienczek Olaf Mosbach-Schulz Giuseppe Stancanelli

JRC IES (maps) Giovanni Strona

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QUARANTINE PEST IN THE EUROPEAN UNION

Xylella fastidiosa is listed in Annex IAI to Directive 2000/29/EC as a harmful organism

• not known to occur in any part of the Union

• relevant for the entire Union

• its introduction into, and spread within, all EU Member States is banned

Each Member State has to immediately notify the presence of Xylella fastidiosa in its territory.

In that event, the Member State has to take all necessary measures to eradicate, or if that is impossible, to inhibit the spread of Xylella fastidiosa.

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CASUAL AGENT OF SERIOUS DISEASES

• Pierce’s disease in grapes • Alfalfa dwarf • Almond leaf scorch • Phony peach disease • Plum leaf scald • Citrus variegated chlorosis • Elm, oak, sycamore leaf scorch • Oleander leaf scorch

Courtesy Helvecio Della Coletta Filho Courtesy Donato Boscia

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DISTRIBUTION OF X. FASTIDIOSA DIFFERENT SUBSPECIES

Diseases caused by X. fastidiosa occur in tropical, subtropical and temperate areas mainly in the Americas and in Taiwan. Recent outbreaks in Italy and in Iran. Uncertainties on some literature reports from other areas (Turkey, India, China etc. )

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Extensive literature search for an up to date inventory of the host range of the bacterial species X. fastidiosa. Currently, based on available data from literature, the host range plants encompass 75 families and at least 359 species*.

An additional complexity level is due to the fact that the actual reported host range is different from strain to strain.

There is high uncertainty with regard to the potential host range of X. fastidiosa in the European flora as a range of European plant species has never been reported to have met the bacterium (first EU outbreak in 2013).

* EFSA Journal 2016

HOSTS

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http://www.efsa.europa.eu/en/efsajournal/pub/4061

An electronic dataset provides a searchable list of host plant species

SEARCHABLE ELECTRONIC DATABASE FOR THE HOSTS OF XYLELLA FASTIDIOSA

Categorisation of plants for planting, excluding seeds, according to the risk of introduction of Xylella fastidiosa

Main title

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Main title

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VECTORS

All xylem-fluid feeding insects in Europe have to be regarded as potential vectors

The transmission of X. fastidiosa by insects is peculiar in that it does not require a latent period yet the bacteria are persistently transmitted

Once infected, adult vectors can transmit during their whole lifetime;

No specificity in the X. fastidiosa transmission by vectors

Studied diseases in the Americas have primarily leafhoppers as vectors

In Europe spittlebugs are much more abundant and diverse Philaenus spumarius has been identified as a vector of X. fastidiosa in Apulia (Saponari et al. 2014)

Further research concerning transmission experiments of other potential vectors is ongoing

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PHILAENUS SPUMARIUS

Among all the European xylem-sap feeder species, so far only for Philaenus spumarius transmission of the Apulian strain of Xylella

fastidiosa has been proved (Saponari et al., 2014.)

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MAIN POTENTIAL VECTORS –PRESENCE IN EUROPE

Potential vectors of Xf are widespread and the introduction in any area might result in the spread of the bacterium via the insect vectors

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POTENTIAL VECTORS IN EUROPE

What is the risk of Xylella fastidiosa for Europe ?

Reported presence of the most widespread species of xylem fluid feeders in Europe (from Fauna Europaea; de Jong, 2013)

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APULIAN SITUATION - 2013 OCTOBER- 2014 AUGUST

Donato Boscia, 2014

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MAIN CONCLUSIONS ON PEST CATEGORISATION

The risks posed by Xylella fastidiosa in the EU territory

X. fastidiosa presents a major risk to the EU territory

It may cause severe direct damage to important crops in Europe, like citrus, grapevine, stone fruits (almond, peach, plum), but also several tree and ornamental plants like oak, sycamore or oleander

The impact on forest is more difficult to assess due to a general lack of data

The environmental conditions required for the establishment are met in many places

It is present in Europe with a distribution restricted to part of the Lecce province in Italian region of Apulia (now also detected in Corsica- Southern France) and is under official control

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PATHWAYS

1. Plants for planting (with or without vector)

2. Infectious insect vectors (both with plant for planting and on their own, as “stowaway”)

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PATHWAYS

Importations from different countries where X. fastidiosa is reported

Entry can occur via plant propagation material

Around 300 host plant species and many of them are imported (often as planting material) into the EU

Survival of transport, storage and management procedures

Transfer to suitable hosts

Uncertainties due to large host range, plant susceptibility, lack of interception records Courtesy of M.B. De Hoop

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ISEFOR database

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CONCLUSIONS ON ENTRY –PLANTS FOR PLANTING

Very likely

The likelihood of entry is rated very high for plants for planting because: the association with the pathway at origin is considered as

very likely for plants for planting due to the fact that 1) plants for planting are seen as a source of the bacterium for outbreaks, 2) host plants can be asymptomatic (Van Eck, 2014) and remains often undetected and 3) very high quantities of plants for planting are imported from countries where X. fastidiosa are reported;

the ability of the bacteria to survive during transport is very likely;

the probability of the pest to survive any existing management procedure is very high since Xylella is often in asymptomatic association with host plants;

the probability of transfer to a suitable host is rated as very high, based on the intended use the plant material for planting (rootstocks) or grafting (scions, budwood) as well as on the fact that host plants are extensively grown in the RA area. Insect vectors are also largely distributed throughout the RA area.

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CONCLUSIONS ON ENTRY–INFECTIOUS VECTORS

Vectors

associated

with plants or

plant parts

Moderately

likely

Vectors

travelling on

their own

Moderately

likely

The likelihood of entry is rated moderate because the pest:

is often associated with the pathway at the origin,

is low to high depending on the conditions of transportation,

the insects are able to survives during transport or storage,

is moderately affected by the current pest management

procedures existing in the risk assessment area,

has moderate limitations for transfer to a suitable host in the

risk assessment area.

The likelihood of entry is rated moderate because the pest:

is often associated with the pathway at the origin;

is low to high depending on the conditions of transportation,

the insects are able to survives during transport or storage,,

is moderately affected by the current pest management

procedures existing in the risk assessment area;

has moderate limitations for transfer to a suitable host in the

risk assessment area.

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UNCERTAINTIES ON ENTRY - PLANTS FOR PLANTING

Medium Distribution and the prevalence of X. fastidiosa in the countries at origin not fully known;

Only a few interception records; Difficulties in assessing the level of susceptible

plant for planting imported within the whole of the EU due to the fact that EUROSTAT data are not collected on a host basis;

Very large host range (ca possible 300 species, see table 6) that is may be even larger – knowledge on host plant susceptibility not complete;

Many plant may host Xylella asymptomatically;

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UNCERTAINTIES ON ENTRY - INFECTIOUS VECTOR

High For both vectors associated with plants or plant parts and vectors travelling on their own, the uncertainties on the probability of entry are considered as high, due to:

Distribution and the prevalence of X. fastidiosa in the countries at origin not fully known;

No data on the interception of vectors in the Europhyt database;

Lack of data on frequency of xylem-fluid feeding insects in traded consignments;

Lack of data for the various vector species; Little information is available regarding the

implementation rate of management procedures previous to or during shipment;

Little data (only H. vitripennis) available on the vectors autonomous dispersal capacity;

Lack of direct, quantitative studies. Little data (only H. vitripennis) available on the vectors' capacity to survive long-distance transportation on its own in vehicles;

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The question is not anymore if Xylella did (will) enter into Europe, the question is how many times did (and will) Xylella enter into Europe ?

Is it possible to precise the route(s) or pathways taken by the bacteria for entering within Europe ?

QUESTION ?

Entry

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ESTABLISHMENT

Host plants and vectors widespread

No natural enemies of X. fastidiosa are known

Climatically suitable environment

Known to occur over large areas in different climatic zones

Is climate a limit?

Does it depend on host crops, vectors and/or X. fastidiosa subspecies?

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IS CLIMATE A LIMIT?

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Main title

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CONCLUSIONS ON ESTABLISHMENT

Very likely

Very high probability of finding a suitable host due to very large range of host plants and potential host plants, and to wide distribution and polyphagy of known and potential vectors;

High apparent capacity of X. fastidiosa to adjust to contrasting climatic conditions. Very high probability to find a climatically suitable environment, with no know adverse abiotic factors, no known natural enemies of X. fastidiosa, but some known for the vectors; conflicting information regarding winter recovery in infected plants;

No fully efficient cultural practices or control measures;

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UNCERTAINTIES ON ESTABLISHMENT

Low

X. fastidiosa already established in Apulia

No uncertainty regarding the availability of a wide range of host plants, but questions regarding the susceptibility of indigenous European flora

One confirmed vector species, widespread, abundant and polyphagous; a large range of additional potential vectors, is yet to be studied

A large range of suitably climatic environments available in the PRA area.

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CONCLUSIONS ON SPREAD

Very likely

Large number of confirmed or potential host plants

Polyphagous, abundant and widespread known vector (P. spumarius)

Difficulty to interrupt all human movements (likely to help in transporting the bacteria or their vectors) between the identified contaminated area and the rest of the PRA area

Difficulty to contain the vectors themselves into the identified contaminated area.

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UNCERTAINTIES ON SPREAD

Medium

The role of human- and wind mediated spread is still poorly documented

There is a lack of data on how far and how fast the disease can be spread

Lack of precise data on how current practices possibly impact insect vectors

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IMPORTANCE OF TRADE AND PLANT MOVEMENT

Main title

Density of AMVER reports, 2011 https://en.wikipedia.org/wiki/AMVER

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IMPACT

Major impact expected when optimal agro-ecological conditions would meet efficient insect vectors

High yield losses and damages

Costly control measures

Environmental consequences

Negative social impact

It is difficult to accurately assess the impact, other than to conclude that crops/regions with adequate conditions for pathogen spread would certainly see serious adverse impacts without the implementation of control strategies

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CONCLUSIONS ON ASSESSMENT OF CONSEQUENCES

Major The consequences are rated as major: • Yield losses and damages would be high and imply

costly control measures in commercial groves, smallholdings and family gardens, and when optimal agro-ecological conditions for the disease coincide with efficient insect vectors.

• Economic impacts are expected to affect agriculture itself, but also the whole economic chain downstream (agro-industry, trade, agro tourism)

• High impact on the cultural, historical, recreational and patrimonial value of the landscape

• Direct impact of insecticide treatments on whole food webs; indirect impact on various trophic levels (e.g. pollination).

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UNCERTAINTIES ON ASSESSMENT OF CONSEQUENCES

Medium to high

• Agro-ecological complexity of the disease depending

on a highly diverse bacterial pathogen • Difficulties in predicting the exact host range of a

given strain

• Lack of knowledge on the potential insect vectors in the RA area

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Xylella now present

Vectors also…

Host numerous

Climatic conditions

And a lot of questions…

Need for answers !

CONCLUSION

What is the risk of Xylella fastidiosa for Europe ?

Main title

https://fr.wikipedia.org/wiki/Cassandre

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THE TEAM

Main title

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QUESTIONS

Many thanks for your attention

Questions / comments

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RISK REDUCTION OPTIONS

Focus on the two main pathways (plants for planting and infective insects)

Need for integrated system approaches,

pest free areas,

surveillance; certification,

production under screenhouse,

control of vectors,

testing for plant propagation material,

preparation, treatment and inspection of consignments

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RISK REDUCTION OPTIONS

Focus on the two main pathways (plants for planting and infective insects)

Need for integrated system approaches,

pest free areas,

surveillance; certification,

production under screenhouse,

control of vectors,

testing for plant propagation material,

preparation, treatment and inspection of consignments

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RRO – PLANTS FOR PLANTING

Prohibition - would be highly effective but its application would be constrained by the very wide potential host range of this pathogen and the large trade flows. This is however a feasible option for high risk commodities .

Limiting the import from pest free areas is considered as highly effective, whereas pest free production sites are assessed as having lower effectiveness unless combined with other measures (e.g. screen house production, certification and testing, vectors control ) in an integrated approach.

Certification schemes, growing plants under exclusion conditions and vectors control have high effectiveness particularly when combined in an integrated approach.

Among consignment treatments, thermotherapy of dormant plants has been applied effectively to control X, fastidiosa in grapevine plants for planting. The import of dormant plants for planting is also effective in preventing the introduction of exotic sharpshooters vectors

Specific insecticide treatments can effectively reduce the likelihood of infective insect vectors being carried together with traded plants.

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EFFECTIVENESS OF RRO IN DIRECTIVE 2000/29/EC

The prohibition of introduction of Citrus, Fortunella, Poncirus and their hybrids, other than fruit and seeds, Vitis, other than fruit, originating in third countries, is an efficient measure to prevent the introduction of X. fastidiosa.

The restrictions for introduction of Prunus are instead not suitable to reduce the risks of introduction of Xylella fastidiosa as plants free from leaves, flower and fruit can still be imported and harbour the bacterium. Nevertheless, many other host plants can still be imported and may carry the bacterium, as shown by the recent documented introductions of coffee plants that harbour X. fastidiosa.

The exemption of official registration for small producers whose entire production and sale of relevant plants are intended for final use by persons on the local market and who are not professionally involved in plant production, considering the very wide host range of X. fastidiosa, could facilitate the local dissemination of the pathogenic agent.

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EFFECTIVENESS OF RRO IN EMERGENCY MEASURES

The exemption of seeds is scientifically justified;

There is very high uncertainty on the host range of the strain of X. fastidiosa in Apulia due to the fact that research is ongoing, and it is very likely that the bacterium has a wider host range than the species listed in the Emergency measures;

The reinforcement of conditions for imports from third countries are assessed as effective;

There is a need for detailed and harmonised protocols for survey, sampling and testing;

There is a need for risk communication to raise the awareness of stakeholders;

The minimum requirements of 2000 meters for buffer zones is clearly not sufficient;

Asymptomatic hosts or asymptomatic infections can escape surveys based solely on visual inspection;

There is a need to limit the infective insect vector populations (e.g. by vectors control, vegetation management, inoculum reduction by removal of infected plants) in the outbreak area. This should be supported by large and detailed systematic surveys organised in the heart of the outbreak, in its vicinity but also more largely.

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RECOMMENDATION

The Panel recommends the continuation and intensification of research activities on the host range, epidemiology and control of the Apulian outbreak of X. fastidiosa. Based on the knowledge acquired by this research, uncertainties could be substantially reduced and a more thorough assessment of the risk and of the mitigation measures could be conducted for the Apulian strain of X. fastidiosa.

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DISEASE SYMPTOMS

Vary a lot, from asymptomatic associations to plants totally defoliated (heterogeneity of symptoms)

Symptom development is dependent on host plant species

In general, affected plants show drying, scorching, wilting of the foliage, eventually followed by plant death as it colonises the xylem (restrict water movement)

Many host plants do not express any symptoms

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Main title

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APULIAN SITUATION

Phylogenetic tree of the Apulian isolate of X. fastidiosa based on multilocus sequence typing (MLST) based on the concatenated sequences of seven genes. The Italian CoDiRO strain is indicated by the green circle (olive)