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Identification, Biology, & Control of Aboveground Pests in FL CitrusJanuary 23, 2019
• What is IPM?
• What kind of information do you need to develop an IPM program?
Managing pests effectively requires knowledge of their population, phenology, and host association(s)
Citrus Production in FL
• Perennial crop
• Historically stable ecosystem regarding insect management• Low insecticide inputs prior to ACP
• Retention of beneficial species (e.g. lady beetles) within/near crops
• More cases of successful biological control than any other cropping system
• ACP + higher insecticide inputs:• T.B.D.
Introduction of invasive citrus pests
1964- Diaprepes root weevil
1995- Brown citrus aphid
L. Buss UF/IFAS
1993- Citrus Leafminer (CLM)
1998- Asian citrus psyllid (ACP)
Arthropod Pests Affecting Florida Citrus Production
• Introduced into California in 1888
• First outstanding success in the field of classical biological control
• Successfully repeated in Florida in 1899
Vedalia lady beetle (Rodolia cardinalis)
Cottony cushion scale (Icerya purchasi)
Arthropod aboveground impacts on citrus
• Fruit damage• Cosmetic vs destructive damage
• Foliage damage• Reduces photosynthetic capacity
• Reduces new growth
• Disease vectors• Insects that move diseases between hosts
Fruit DamageDirect damage to fruit
• Feeding reduces fruit quality, shape, or size
• Reduction in yield or cause fruit to drop
• Problem for fruit grown for fresh & processed markets
Damage to peel
• Largely cosmetic
• Problem for fresh market
Damage from leaf-footed bug feeding.
Weeks UF/IFAS CREC
Thrips feeding damage on peel.
UF/IFAS CREC
Stinkbugs and Leaf-footed bugs
Use piercing-sucking mouthpart topuncture fruit & feed. Feeding holes create openings for secondary pests/pathogens to enter including bacteria, fungi, and other insects.
Weeks UF/IFAS CREC Weeks UF/IFAS CRECWeeks UF/IFAS CREC Weeks UF/IFAS CREC
Weeks UF/IFAS CREC
Rust mitesPredominant arthropod pest of fresh & processed
citrus in Florida
Citrus rust mite
(Phyllocoptruta oleivora)
Pink citrus rust mite
(Aculops pelekassi)
UF/IFAS CREC UF/IFAS CREC
• Damage• Feeding injury • Russeting of fruit & leaves• Mild to severe distortion of new leaf
growth• Brown lesions on lower surfaces &
along midribs of mature leaves• May produce mesophyll collapse,
chlorosis, and leaf drop
Rust mite damage to citrus
Leaf distortion on new growth
Citrus rust mitePhyllocoptruta oleivora (Ashmead)
UF/IFAS CRECUF/IFAS CREC
Rust mite development
• Females lay 2 eggs/day
• ~30 eggs in a lifetime
• Egg adult in 6 days
• Adult male longevity approx. 6 days
• Adult female longevity approx. 14 days
Citrus rust mite seasonalityPhyllocoptruta oleivora (Ashmead)
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec0
UF/IFAS CREC
CRM populations peak in early summer, then again at a smaller scale in mid-late fall depending on weather.
Pink citrus rust miteAculops pelekassi (Keifer)
UF/IFAS CREC UF/IFAS CREC
PCRM damage to fruit appears as bronzing all over because it is done early in the fruit’s development.
Pink citrus rust mite (PCRM)Aculops pelekassi (Keifer)
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec0
PCRM populations peak in mid spring/early summer.Populations build up on flowers & leaves prior to feeding on fruit.
UF/IFAS CREC
Early in the season, pink citrus rust mites are more prone to damage leaves than the citrus rust mite
Natural enemy complex for rust mites
Phytoseiid image: http://keys.lucidcentral.org/keys/v3/phytoseiidae/key/phytoseiidae/Media/Html/mites.htmTydeid image: https://de.wikipedia.org/wiki/Datei:Yellow_mite_(Tydeidae),_Lorryia_formosa.jpg
Citrus rust mites
Stigmaeidae
A. Pelegrin
Cheyletidae
E. McDonald
Phytoseiidae
Tydeidae
Disease(next slide)
Other predacious arthropods:lady beetles, ants, spiders,
lacewing larvae….
Hirsutella thompsoniiFungal pathogen of mites, biological control for rust mites in citrus
Control of CRM by
Hirsutella
Action thresholds for control of rust mites
• Processed fruit• 10 rust mites / 2 cm2
• Controlled with 1-3 oil or miticide applications/season
• Fresh fruit• 2 rust mites / 2 cm2
• Controlled with 3-5 miticide applications/season
Citrus mealybugPlanococcus citri• Most commonly found in spring and early summer
• Prefer sheltered locations
• Females lay 300-600 eggs
• Damage
• Feeding causes cosmetic damage to fruit
• Produce large amounts of honeydew, leads to problems with sooty mold
• Can cause heavy fruit drop in grapefruit
• Cultivars most affected: grapefruit, navals, valencia
Natural enemies of citrus mealybug
• Mealybugs generally occur at low levels and are kept in check by three natural enemies:
• Cryptolaemus montrouzieri
• Lady beetle
• The “mealybug destroyer”
• Found in groves May-June
• Entomophthora fumosa
• Fungus
• Prevalent after summer rainy season starts
• Leptomastidae abnormis
• Hymenopteran parasitoid
Various species of lady beetles (Coccinellidae) contribute to the mortality of several citrus pests.
Cryptolaemus montrouzieri- “mealybug destroyer”- Efficient predator of mealybugs despite
the waxy covering- Nymphal stages LOOK like mealybugs- Can be purchased for release, but there
are drawbacks…
Nymph Adult
Control of Mealybugs
• Effective products for mealybugs have negative impacts on beneficial insect populations
• Insecticides should ONLY be applied to severe infestations
• Applications are most effective when applied before mealybugs have settled between fruit clusters
• Fruit clusters serve as shelter from
management actions BUT naturally
occurring predators can often reach
these locations
Scale insect pests of citrus• Several species of ARMORED SCALES can be problematic
• Red scale, purple scale, Chaff scale
• Scale insects in Florida have historically been under biological control by a large number of natural enemies
• Not currently considered key pests in the development of pest management programs
D. Papacek http://thecitrusguy.blogspot.com/2012/05/citrus-with-some-mussel.html
“Secrets to success” for biological control of scale insects• Adult scales are sessile- either VERY slow moving or not moving at
all
• High number of offspring to support natural enemy population growth
• Populations tend to be concentrated easy for natural enemies to find
Aggregation of red scale on green fruit
Florida red scaleChrysomphalus aonidum• Damage
• Feeding occurs on leaves, green twigs, and fruit
• Feeding causes discoloration at the feeding siteUF/IFAS CREC
UF/IFAS CREC UF/IFAS CREC
Florida Red Scale (Chrysomphalus aonidum)
• Red scale now under biological control by parasitic wasps released in Florida (Aphytis wasps)
• Good example of successful classical biological control
Florida red scale• Left: FRS Adult Female with Cover Lifted
• Lower left: 3rd instars of Aphytis holoxanthuson adult female scale
• Below: 5 fresh pupae of Aphytis holoxanthusunder FRS cover
Purple scaleLepidosaphes beckii
• Once major pest of fruit, leaves, and twigs
• Populations are highest in late spring/early summer
• Parasitoid (Aphytis lepidosaphes) introduced in 1950s to manage
UF/IFAS CREC
Parasitoid emergence hole
UF/IFAS CREC
Chaff scaleParlatoria pergandii• Often found on trunk and inner canopy
• Fruit feeding causes spotting
• Slow rate of reproduction + parasitoid Aphytis hispanicus historically kept populations low
UF/IFAS CREC
UF/IFAS CREC
Thrips• Flower thrips
• Frankliniella bispinosa
• Frankliniella kelliae
• Orchid thrips
• Chaetanaphothrips orchidii
• Danothrips trifasciatus
• Greenhouse thrips
• Heliothrips haemorrhoidalis
• Chili thrips
• Scirtothrips dorsalis
L. Buss UF/IFAS UF/IFAS CREC
Thrips move between plants, making them a huge challenge to manage.
Thrips populations can reach high numbers in flowers (semi-protected)& lead to fruit damage
F. bispinosa collected from 20 open flowers/rep in March 2001 (Hillsborough Co.)
Variety Adults Larvae
Murcott 604 203
Murcott 815 379
Murcott 602 611
Rhode Red Valencia 2,166 1,696
Rhode Red Valencia 2,749 1,488
Rhode Red Valencia 2,468 855
Rhode Red Valencia 2,061 1,070
Control of F. bispinosa on ‘Navel’
Treatment Insecticides RateApplication
dateMean no. fruit/m3
% yield increase
1
Chlorpyrifos 4EC 7.01 L 14 Feb
34.2a 43Formetanate
hydrochloride 92 SP1.4 kg 1 Mar
2
Dimethoate 4 EC 8.18 L 14 Feb
33.9a 42Formetanate
hydrochloride 92 SP1.4 kg 1 Mar
3Formetanate
hydrochloride 92 SP1.4 kg 15 Feb 27.9b 17
control n/a -- -- 23.9c --
Childers. 1992. J. Econ. Entomol. 85: 1330-1339
1921 The Citrus Industry 2(3): 19
J.R. Watson
1940 The Citrus Industry 21: 5, 8-9, 12-13, 17
“…the so-called thrips marks are
caused by the young fruit being
rubbed against leaves and
twigs…not by thrips.” (W.C. Thompson)
Does F. bispinosa cause scarring damage to ‘Murcott’ fruit?
Thrips caging study on ‘Murcott’ blooms
Outcome of caging study:
Caged study- 35 days after caging
No thrips 10 thrips 25 thrips
UF/IFAS CREC
Thrips feeding damage on ‘Murcott’
fruit
No Economic Injury Level set
UF/IFAS CREC UF/IFAS CREC
Orchid and Greenhouse Thrips
• Cause rind blemishes on developing fruit, in particular “ring spotting”
• Develop in protected areas (under calyx, between touching fruit)
• Primarily a problem on red grapefruit varieties but can occur on white grapefruit varieties as well
UF/IFAS CREC
UF/IFAS CREC
UF/IFAS CRECUF/IFAS CREC
Ring scarring where fruit in clusters were touching
Monitoring Orchid and Greenhouse thrips
• Examine interior clusters of red grapefruit when fruit are beginning to touch
• Use 10x hand lens to search for thrips (larvae and adults) on fruit where touching
• If most clusters sampled contain thrips, then insecticide application may be justified
•This damage is cosmetic in nature and does not affect internal fruit quality
Chili Thrips(Scirtothrips dorsalis)
• Recently introduced pest in Florida (2005)• Damage leaves and scar fruit
Host Plants:Over 150 host plants including banana, beans, chrysanthemum, citrus, corn, cotton, cocoa, eggplant, ficus, grape, grasses, holly, jasmine, kiwi, litchi, longan, mango, onion, peach, peanut, pepper, rose, soybean, strawberry, tea, tobacco, tomato, viburnum, etc.
Chili Thrips damage
Rose Ligustrum (Privet)Pittosporum
Indian Hawthorn Schefflera Strawberry
Scirtothrips spp. (Thysanoptera: Thripidae)
S. aurantii Faure - (South Africa)
S. dorsalis Hood – (Japan & Africa)
S. citri (Moulton) – (California & Arizona)
Scirtothrips citri(Moulton)
Foliage Pests
• Primarily concerned with protection of foliage on young trees
• On mature trees, a few pests are occasionally problematic (i.e., spider mites)
• Pest problems typically associated with new flush
Young Trees
Goal: Optimize tree growth and vigor to bring trees into production within 3-4 years after setting
Young tree pest problems
UF/IFAS CREC
Citrus leafminer (CLM)- Phyllocnistis citrella
CLM history in Florida
• First recorded in Homestead in Spring 1993
• By December it spread up to the Georgia border
Citrus LeafminerLifecycle
Egg2-10 days
4 larval instars5-22 days
Pupal stage6-22 days
CLM can also cause damage to green twigs and in rare cases cause mining on fruit surface
Seasonality of CLM in Florida
• overwinter as adults with no reproductive diapause
• very low populations exist throughout winter months on the low levels of new flush being produced
• with warmer weather, CLM produce more offspring more rapidly
• populations build up to noticeable levels when the summer flush occurs (usually May to June)
3/3
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Me
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Leaf damage
Bearing citrus 2006
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Leaf damage
Non-bearing citrus 2006
Importance of CLM Damage
• Damage alone not significant on mature trees (New flush : Canopy)
• Damage on non-bearing trees can reduce tree growth
• Increased time to bring trees into production
Canker / CLM Relationship
• Canker incidence can be up to 50% higher in groves where CLM damage is abundant (Sohi and Sandhu, 1968)
Choice & Timing of Pesticide Applications
Non-bearing/young citrus
• soil-applied imidacloprid application is the best option for preventing CLM damage (current UF/IFAS recommendation)
• applications should be made 10-14 days prior to anticipated flush
• expect about 8 weeks of control
• soil-applied imidacloprid just prior to summer flush and again just prior to the fall flush should provide control of CLM during this peak time for CLM damage
• may also provide control of Asian citrus psyllid during these times as well
Choice & Timing of Pesticide ApplicationsBearing citrus• preventing damage on bearing trees for canker management much
more difficult
• must rely on foliar applications if control warranted
• there are no soil-applied systemic insecticides available for CLM control on large, bearing trees
• as a general rule, there have never been any soil-applied systemic organophosphate or carbamate insecticides shown to provide effective control of CLM damage
• this includes aldicarb (Temik)*, dimethoate, oxamyl (Vydate), metasystox(MSR)
*Temik no longer registered for use in citrus
Soil imidacloprid application: Sept. 4; Foliar applications: Sept. 18
Control of Damage by Citrus Leafminer
June 6 June 13 June 21
0
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40
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60
Pe
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Spintor
Agri-mek + oil
Untreated
Control of Damage by Citrus Leafminer
Foliar treatments applied May 19
Timing of application for leafminer control
13 days from general budbreak is earliest time for application
Last potential date for leafminer application is 31 days after budbreak
[FOLIAR APPLICATIONS]
Effects of cultural practices on CLM populations
• Promoting winter flush may result in higher CLM populations earlier in the season
• hedging and topping
• excessive irrigation
• fertilization regimes
Biological Control of Citrus LeafminerAgeniaspis citricola: Imported into Florida from Australia in 1994
BEFORE intense ACP management, parasitism rates up to 86%were observed late in the season.
NOW-?
Use of Pheromones in Leafminer Management
Non-pesticide approaches to CLM control–Previous lecture by L. Stelinski
http://cisr.ucr.edu/images/citrus_laef_miner_1.jpg
Aphids
Aphids
• Depend on newly expanding leaves for their development
• Leaf curling
• Large amounts of honeydew (blocks photosynthesis)
• Treatment warranted on young trees when > 50% of new foliage is infested
Brown Citrus Aphid (BCA)
Toxoptera citricida
Vector of citrus tristeza virus
*CTV locally absent
Aphid predators!Pseudodorus clavatus
Syrphid flyLarvae are predacious
https://www.treknature.com/gallery/photo269910.htm
Lady beetlesAdults & larvae predacious
J. Penney
M. Quinn
https://commons.wikimedia.org/wiki/File:Harmonia_axyridis_larvae_2.jpg
M. Quinn
Cycloneda sanguinea Harmonia axyridis
Green lacewingsLarvae predacious
B. Newton
Drees
Citrus Whitefly, Dialeurodes citri•Serious pest in the 1900-1930’s
• No longer a serious problem thanks to introduced parasitoid, predatory arthropods, and parasitic fungi
Citrus whitefly eggs Whitefly nymphs- translucent, produce large amounts of honeydew (1st instar has legs, absent in later instars)
Both male and female adults are winged.
FDACS-DPI
Natural Enemies of Citrus Whitefly
Exotic parasitoid of Citrus Whitefly,
Encarsia lahorensis
Successfully established in Florida in 1977
Whitefly nymph with parasitoid larva and pupa
Whitefly Fungi
Aegerita sp.Aschersonia spp.
Effective with the right environmental conditions
Copper sprays inhibit growth of these “friendly fungi”
Foliage pest concerns in mature trees
• Pests that reduce the overall health of the tree
• Cause leaf and/or fruit drop
• Produce honeydew, promoting sooty mold development
Spider Mites
Citrus Red Mite (Panonychus citri)
Texas Citrus Mite (Eutetranychus banksi)
Spider Mites
• Dry conditions favor rapid population growth
• Natural enemies exist, but can’t keep up with populations under dry conditions
• Highest populations September – May (dry period)
• 5-10 spider mites per leaf is action level for treatment if populations are not in decline
• Higher percentage of males indicates population declining
Leaf drop caused by spider mites (January)
Male (long legs)Females (Short legs)
Many females, eggs present, few males = population rapidly growing
Black Scale, Saisettia neglecta
Brown Soft Scale, Coccus hesperidum
Cottony Cushion Scale, Icerya purchasi Green scale, Coccus viridis
Scale pests of foliage
Honeydew from scale insects deposited on leaves = sooty mold
Why do many Hemipterans produce honeydew?
• too much water can be a bad thing
• mechanism to cope with foods high in water content
Scale insects psyllids
ForegutTemporary storage and grinding of food
MidgutDigestion & absorption of nutrients into body
Alkaline pH ≥ 7
HindgutRe-absorption of water, salt & other nutrients before excretion of (dry) nitrogenous waste (frass)
Insect Digestive and Excretory Systems
honeydew producers
FC = filter chamber; used to pass water directly out the rectum
thus concentrating plant sap before it is absorbed into the insect
body
Insects and Mites associated with plant
diseases
Brief overview of biology…
Asian citrus psyllid – Diaphorina citri
First found in Florida June 1998
Citrus Greening Disease
Asian Citrus Psyllid Distribution (FL)
• First detected in dooryard citrus trees in south Florida in 1998
• subsequent finds in nursery plants (orange jasmine [Murraya paniculata]) in discount stores throughout the state
• psyllid well established in primary citrus growing areas of FL and cannot be eradicated
Picture taken 1.4.19 in CREC groves
After Asian citrus psyllid colonized SE Florida (red), it moved on Murrayapaniculata to other counties very rapidly.
Rapid movement made eradication unfeasible
Found in SE areas of Texas and Mexico and CA in 2008
The “Home Depot” Effect
egg adult in 2 weeks at 75-80°F
5 nymphal stages
Life cycle takes 15-47 days
10 generations / year
Asian Citrus Psyllid (ACP)
• 3-4 mm in length
• mottled wings
• Adult psyllids can feed on both new and mature leaf flushes; prefer young leaves
• When young leaves not available, adult psyllids are found on underside of mature leaves feeding on leaf midvein
• Mean longevity of females increases with decreasing temperature within 59-86°F / 15-30°C
Adult ACP
Adults gather at newly
emerging growing tips and on
young flushes, feed and mate
Factors affecting psyllid populations
The two main factors regulating psyllid population growth are:
1.Temperature
2.New leaf flush (resource availability)
Adults oviposit ONLY on young leaf
flush
Eggs are about 0.3 mm long and
almond shaped
Eggs are pale when deposited, turn
yellow then orange as they mature.
Often difficult to see without hand
lens
Asian Citrus Psyllid Eggs
**
*
*
Duration of EGG STAGE (in days) and HATCH SURVIVAL
Temp (°F/°C) Days to hatch Survival
50°F / 10°C 0 0
59°F / 15°C 9.74 ± 0.23 84.5%
68°F / 20°C 7.03 ± 0.11 89.4%
77°F / 25°C 4.15 ± 0.07 95.5%
82°F / 28°C 3.46 ± 0.09 96.2%
86°F / 30°C 3.29 ± 0.06 93.2%
91.4°F / 33°C 0 0
Data from Liu & Tsai, 2000. Ann. Appl. Biol. 137:201-216.
Psyllid developmental times (in days)
Temp (°F/°C) Egg to adult
50°F / 10°C 0
59°F / 15°C 49.3± 0.4
68°F / 20°C 28.8± 0.5
77°F / 25°C 17.0± 0.2
82°F / 28°C 14.1± 0.2
86°F / 30°C 16.3± 0.3
91.4°F / 33°C 0
Data from Liu & Tsai, 2000. Ann. Appl. Biol. 137:201-216.
• 0.3 mm long in the first instar
• 1.6 mm long as fifth instars
• Nymphs are yellow in color with red eyes and visible wing pads in larger nymphs
Asian Citrus Psyllid Nymphs
• early nymphal stages easily mistaken for aphids • white carbohydrate secretions provides an easy means of
distinguishing from aphids at a distance.
Asian Citrus Psyllid Nymphs
Nymphal developmental times (in days)
Temp (°F/°C) Total nymphal stages Survival (%)
50°F / 10°C Failed to develop beyond 3rd instar
0
59°F / 15°C 39.6 ± 0.3 61.9
68°F / 20°C 21.8 ± 0.4 69.8
77°F / 25°C 12.8 ± 0.2 75.4
82°F / 28°C 10.6 ± 0.2 83.9
86°F / 30°C 13.0 ± 0.3 73.7
91.4°F / 33°C Failed to develop beyond 4th or 5th instar
0
Data from Liu & Tsai, 2000. Ann. Appl. Biol. 137:201-216.
Low temperature developmental thresholds
1st instar 53°F (11.7°C)
2nd instar 51°F (10.7°C)
3rd instar 50°F (10.1°C)
4th instar 51°F (10.5°C)
5th instar 52°F (10.9°C)
Effects of Cold Weather on Psyllid Populations
January 2-3, 2008
CREC Research Grove8-10’ ‘Hamlin’ orange
Evaluating psyllid mortality• Caged 600 psyllids (30 psyllids/tree)
• Cages placed in plots with and without freeze protection (irrigation)
• Inside vs outer canopy
Factors Evaluated
• Freeze protection vs. no freeze protection
• Effects of location of psyllids in tree canopy
• Recorded leaf temperatures and trunk base temperatures every 2 hours
• Data loggers within cages recorded temps every 15 mins.
• Weather station data also collected
CREC Jan 3, 2008 (8:00 AM)
CREC Temps (Jan 2-3, 2008)
10+ hrs below freezing
Effects of Freeze Protection on Psyllid Survival
F = 3.55P = 0.076
Mortality of Psyllids Located Inside and Outside Canopy
F = 2.31P = 0.1455
Overall psyllid mortality from freezingAverage mortality rate: 60.8%
Minimum mortality observed: 20.7%• Lowest mortality in freeze protection plots
• With no freeze protection lowest 41.2%
Maximum mortality observed: 86.8%
Conclusions
• At CREC location sustained freezing temperatures reduced psyllid populations an average of 60%
• Psyllid mortality likely to vary by location based on duration and intensity of cold
• Cold temperatures in the citrus growing regions of Florida are not enough to reduce the need for early season psyllid control
Psyllid feeding damage
In the absence of the greening pathogen, psyllid control previously targeted young trees to protect new growth from damage that results in reduced tree growth.
Dieback of new growth
Witches broom effect
Psyllid nymphs produce waxy secretions similar to aphid or scale insect honeydew
Sooty mold - growing on sticky residues from secretions from psyllid nymphs
Monitoring Psyllid PopulationsImportant to monitor when new flush is available
Critical time is spring and fall when temperatures are cooler and flush is abundant
Check expanding terminals for aggregations of psyllids
Adult psyllids found on underside of leaves near leaf midvein when no new flush is available
Eggs tucked away in very young, newly forming leaves and leaf buds.
Monitoring Psyllid Populations
Inspect new leaf and shoot flushes of citrus and citrus relatives such as orange jasmine, Murraya paniculata. Look for white honeydew and leaf distortion on new leaf flush and shoots.
Monitoring Psyllid Populations
Biological Control of Psyllids
There are numerous natural enemies of psyllids present that suppress psyllid populations, especially in the summer and fall
Use of broad spectrum foliar insecticides will present a problem in maintaining populations of the natural enemies of psyllids and other potential pest species
Natural Enemies of Juvenile D. citri in Florida
SpidersHibana velox (Anyphaenidae) Chiracanthium inclusum (Clubionidae)Hentzia palmarum (Salticidae)Oxyopes sp. (Oxyopidae)
Ladybeetles (Coccinellidae)Curinus coeruleusCycloneda sanguineaExochomus childreniHarmonia axyridisOlla v-nigrum
Green Lacewings (Chrysopidae)Chrysoperla rufilabrisCeraeochrysa spp. (2 - 3)
Hoverflies (Syrphidae)Allograpta obliqua
Brown Lacewings (Hemerobiidae)Micromus posticus
ParasitoidsTamarixia radiata
Hemiptera (Anthocoridae)Orius sp.
Ants (Formicidae)Dorymyrmex bureniPseudodmyrmex gracilis
Biological Control:
Olla v-nigrum
J. P. Michaud
Biological Control:Harmonia axyridis
Multicolored Asian ladybeetle
Tamarixia radiata• External Parasite• Originally from India• Mass reared & released by FDACS• Variable incidence in Florida
“Classical” Biological Control
Tamarixia radiata: life stages
Adult finding host
Adult laying egg Egg attached to abdomen of ACP
Larva attached to underside of ACP, consuming internal tissues
Pupa- will emerge through body of ACP
http://www.fftc.agnet.org/library/article/tn2001005.html#6
Tamarixia Survey 2006-07(old, pre-ACP area-wide management attempts)
• surveyed major citrus growing areas
• establishment of Tamarixia?
• parasitism rates?
0
20
40
60
80
100
M A M J J A S O N D J F M A
T. ra
dia
tap
ara
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(%
)
2006-2007
C
Tamarixia survey 2006-07
average parasitism rates less than 20% throughout most of the season
Additional Parasitoid Introductions
• Diaphorencyrtis aligarhensis• Encyrtidae
• Originally released along with T. radiata; failed to establish
• Additional releases made with parasitoids from geographic regions with climates more similar to FL
Chemical Control of the Asian Citrus Psyllid
Recommendations updated annually in Citrus Production Guide*
*Current chapter:https://crec.ifas.ufl.edu/media/crecifasufledu/extension/plant-pathology-/florida-citrus-production-guide/pdf/ACP-and-Leafminer.pdf
Soil-applied Insecticides for Psyllid Control
Young trees (< 6-8 feet tall)
• Soil applied systemic insecticides are most effective (imidacloprid, thiamethoxam, clothianidin)
• must be applied about 2 weeks prior to flush for best results
• in sandy soils, can be washed away if heavy rains occur with 12 -24 hr post treatment
• have fewer negative effects on natural enemy populations
Foliar-applied Insecticides for Psyllid Control
Use on both young and mature trees:
• best to target psyllids before new flush present
•Control adults before eggs laid
• typically broad-spectrum products
• most have negative effects on natural enemies
•Will discuss in more detail later (next lecture)
Brevipalpus mites and Citrus Leprosis
Tenuipalpidae
• Over 622 species in 26 genera worldwide
• False spider mites, flat mites
• Primarily found in tropical/subtropical areas
• Genus Brevipalpus most important economic group
Egg
Larva
Photochrysalis
Protonymph
Deutochrysalis
Deutonymph
Teliochrysalis
Adult Female
Adult Male
50-60/female
Comparative developmental rates, egg production and adult longevity of Brevipalpusphoenicis and Panonychus citri at 270 C
(Duration in days)
B. phoenicis P. citri
Egg 6.0 3.4Larva 4.8 1.9Protonymph 4.8 1.6Deutonymph 4.9 2.3Egg-Adult 20.7 12.0Adult Longevity 20.4 -
Host Oroxylum indicum Citrus sp.
Authors: Beavers & Hampton 1971; Lal 1978; Saito 1979
Brevipalpus californicus, B. obovatus and B. phoenicis
Two problems:•Mites can develop to large numbers on various
host plants. They have toxic saliva that can result in feeding injuries to citrus and other economic crops.
•Mites are vectors of one or more unassigned Rhabdoviruses in citrus, coffee, passion fruit, orchids and numerous woody ornamental
plants.
Brevipalpus spp.
Examples of direct feeding damage – The following
images ARE NOT LEPROSIS
Leprosis
• Problem on sweet orange varieties
• Caused by virus that is not systemic in plant
• B. phoenicis is the only confirmed vector
• Miticide costs on Brazilian citrus exceed 90 million US dollars per year (Omoto 2000)
• Currently not in Florida (is present in Mexico)
Citrus Leprosis (symptoms)
• Chlorotic leaf lesions becoming brown with or without necrotic centers
• Flat or slightly raised necrotic areas on twigs and leaves
• Flat or depressed lesions on fruit with concentric patterns and gumming
• Abscission of leaves and fruit and twig dieback due to extensive lesion development
Leprosis: Fruit Lesions
Leprosis : Fruit Drop
Sharpshooters and Citrus Variegated Chlorosis
Citrus Variegated Chlorosis• Causal agent Xylella fastidiosa, a xylem limited
bacteria
• Found in Brazil, Argentina, Paraguay, and more recently identified in Costa Rica
• Transmitted by sharpshooter leafhoppers
• Infects most citrus cultivars
Next Lecture…
• How to develop a comprehensive pest management program in the presence of ACP/HLB
• Insecticides and modes of action