Entomology Research Updates

Psyllid transmission of greening and chemical control of psyllids

Entomology Research Updates

Psyllid transmission of greening and chemical control of psyllids

Michael E. RogersUF / IFAS / Citrus Research and Education

Center, Lake Alfred

Michael E. RogersUF / IFAS / Citrus Research and Education

Center, Lake Alfred

Psyllid / HLB Studies (current progress)

Psyllid / HLB Studies (current progress)

• Pathogen acquisition by adults and nymphs– Laboratory– Field

• Seasonality of HLB infected psyllids– survey work

• Effects of insecticides on pathogen transmission

• Results of multi-pest efficacy trial

• Pathogen acquisition by adults and nymphs– Laboratory– Field

• Seasonality of HLB infected psyllids– survey work

• Effects of insecticides on pathogen transmission

• Results of multi-pest efficacy trial

Psyllid Acquisition Rates (laboratory studies)

Psyllid Acquisition Rates (laboratory studies)

• Psyllids which fed as adults on HLB (+) plants

• Average acquisition rate of 20-30%

• Psyllids which fed as adults on HLB (+) plants

• Average acquisition rate of 20-30%

Greening Infected Adult Psyllids

% in

fect

ed

Feeding Time (days)

Psyllid Acquisition Rates (laboratory studies)

Psyllid Acquisition Rates (laboratory studies)

• Adult psyllid reared on HLB (+) plants (nymphs fed entire time on infected plant)

• Percentage of HLB (+) adult psyllids ranged from 11.6% to 100%

• Adult psyllid reared on HLB (+) plants (nymphs fed entire time on infected plant)

• Percentage of HLB (+) adult psyllids ranged from 11.6% to 100%

Psyllid Acquisition Rates (field studies)

Psyllid Acquisition Rates (field studies)

• Caging Studies– Acquisition by adults vs nymphs

• Caging Studies– Acquisition by adults vs nymphs

Psyllid Acquisition Rates (field studies)

Psyllid Acquisition Rates (field studies)

• Adult psyllids caged on HLB (+) plants– 1 out of 1,000+ psyllids tested HLB (+)

• Adult psyllids reared from nymphs on HLB (+) plants– Percentage of adults testing HLB (+) ranged from 0%

to 100%– Variation probably due to differences in pathogen

levels in different parts of the plant

• Adult psyllids caged on HLB (+) plants– 1 out of 1,000+ psyllids tested HLB (+)

• Adult psyllids reared from nymphs on HLB (+) plants– Percentage of adults testing HLB (+) ranged from 0%

to 100%– Variation probably due to differences in pathogen

levels in different parts of the plant

Seasonal Psyllid Infection RatesSeasonal Psyllid Infection Rates• Monthly collections of “wild” psyllid

populations

• DNA extraction / PCR of psyllids to detect presence of HLB pathogen

• 8 grove sites in 5 Florida counties including:– DeSoto, Highlands, Okeechobee, Polk and St. Lucie

counties

• HLB (+) trees have been found in all of these locations

• Monthly collections of “wild” psyllid populations

• DNA extraction / PCR of psyllids to detect presence of HLB pathogen

• 8 grove sites in 5 Florida counties including:– DeSoto, Highlands, Okeechobee, Polk and St. Lucie

counties

• HLB (+) trees have been found in all of these locations

0

500

1000

1500

2000

2500

3000

3500

4000

4500

Jan Feb Mar Apr May Jun Jul Aug

0

0.001

0.002

0.003

0.004

0.005

0.006

Infe

ctio

n R

ate

Sam

ple Size (N

)

Total # psyllids sampled

Psyllid Infection rate and sample size averaged for all Florida sites.

Preliminary Data (Jan-Jul 2008)

0.2%

0.5%

• the highest monthly infection rate found in a single grove thus far was 1.6%; high number of HLB (+) trees

• No infected psyllids were found in most groves; these groves did have varying degrees of HLB management programs

Small sample size

Summary of Results…to dateSummary of Results…to date• Overall psyllid infection rates in

the field are likely less than 1%

• Only saw rates >1% where HLB infected trees were still present

• There may indeed be some fluctuation in abundance of infected psyllids throughout the year – preliminary data

• Overall psyllid infection rates in the field are likely less than 1%

• Only saw rates >1% where HLB infected trees were still present

• There may indeed be some fluctuation in abundance of infected psyllids throughout the year – preliminary data

Summary of Results…to dateSummary of Results…to date

• Acquisition rates by adult psyllids in field appear to be low

• Higher rates in lab (plant health)

• Very high rates of infection are possible from adults reared as nymphs on HLB (+) plants; will vary based on HLB levels in plant

• Acquisition rates by adult psyllids in field appear to be low

• Higher rates in lab (plant health)

• Very high rates of infection are possible from adults reared as nymphs on HLB (+) plants; will vary based on HLB levels in plant

Implications for Managing HLB ?Implications for Managing HLB ?

• IF…you cant control 100% of the psyllids 100% of the time

• IF…100% (or even 50%) of the psyllid nymphs on HLB (+) trees acquire the pathogen

• CAN HLB be managed without removing infected trees?

• IF…you cant control 100% of the psyllids 100% of the time

• IF…100% (or even 50%) of the psyllid nymphs on HLB (+) trees acquire the pathogen

• CAN HLB be managed without removing infected trees?

Vector Management using insecticides

Vector Management using insecticides

• Preventing transmission

• Reducing overall psyllid populations

• Preventing transmission

• Reducing overall psyllid populations

Can insecticides prevent pathogen transmission?Can insecticides prevent pathogen transmission?

• Soil-applied systemic insecticides– Mortality caused by feeding prior to transmission?

• Foliar insecticides– Does contact with residues cause mortality prior to

transmission?

• If insecticides can prevent transmission, how long does such protection last?– Effects of residue degradation?

• Soil-applied systemic insecticides– Mortality caused by feeding prior to transmission?

• Foliar insecticides– Does contact with residues cause mortality prior to

transmission?

• If insecticides can prevent transmission, how long does such protection last?– Effects of residue degradation?

Ongoing studies:Ongoing studies:

• imidacloprid treated and untreated plants challenged with HLB (+) psyllids

• imidacloprid treated and untreated plants challenged with HLB (+) psyllids

Ongoing studies:Ongoing studies:• Currently holding more than 100

plants; no PCR positives to-date

• Positive transmission results could take 8-12 months

• Early symptoms can be a bit confusing

• Currently holding more than 100 plants; no PCR positives to-date

• Positive transmission results could take 8-12 months

• Early symptoms can be a bit confusing

Huh?!?

Electrical Penetration Graph (EPG) – measure psyllid feedingElectrical Penetration Graph (EPG) – measure psyllid feeding

EPG StudiesEPG Studies

• Determine exact feeding time required for pathogen transmission / acquisition

• Determine whether insecticides can disrupt feeding prior to transmission

• Determine how long insecticides (residues) provide disruption of psyllid feeding / pathogen transmission

• Determine exact feeding time required for pathogen transmission / acquisition

• Determine whether insecticides can disrupt feeding prior to transmission

• Determine how long insecticides (residues) provide disruption of psyllid feeding / pathogen transmission

Control of Asian citrus psyllid, citrus leafminer and citrus rust mite

Trial 2008-10M.E. Rogers

UF / IFAS / Citrus Research & Education Center, Lake Alfred

Treatments1 Dimethoate 4E + LI 700 1 pint/A ; 0.25% v/v

2 Dimethoate 4E + LI 700 2 pints / A ; 0.25% v/v

3 Agri-mek 0.15EC + FC 435 oil 20 oz / A ; 2% v/v

4 Agri-mek 0.15EC + FC 435 oil 10 oz / A ; 2% v/v

5 Sevin XLR + LI 700 2 quarts/A ; 0.25% v/v

6 Provado 1.6F + LI 700 10 oz / A ; 0.25% v/v

7 Movento 240SC + LI 700 10 oz / A ; 0.25% v/v

8 Movento 240SC + FC 435 oil 10 oz / A ; 3% v/v

9 Envidor 240SC 15 oz / A

10 Imidan 70W + LI 700 1.5 lbs / A ; 0.25% v/v

11 Mustang 1.5EW 4.3 oz / A

12 Danitol 2.4EC 16 oz / A

13 Micromite 80WGS + FC435 oil 6.25 oz / A ; 2% v/v

14 Portal 0.4EC + FC 435 oil 4 pints / A ; 2% v/v

15 Delegate 25WG + FC 435 oil 4 oz / A ; 2% v/v

16 Lorsban 4E 5 pints / A ; 2% v/v

17 Untreated ---

Trial Location• ConservII – MidFlorida Citrus Research

Foundation Grove• Variety – ‘earlygold’• Treatment dates: June 24-25, 2008• Trial still under evaluation (8/8/08)• Plot size: 15 trees (3 x 5)• A foliar fertilizer was tank-mixed with all

treatments • (DiamondR Ultra M2F; Sulfur 3.2%; Iron 1.6%; Mn

2.0%; Zn 2.4%)

Pesticide active ingredient

Target pestEffects on

natural enemiesMode of Action1 Psyllid Leafminer Rust Mites Spider Mites Root Weevil

Adults Scale Insects Mealybugs

Abamectin + oil 6 ++ +++,R +++,R + + (oil) +(oil) + (oil) mediumAcetamiprid 4 - +++,R - - ? + ++ mediumAldicarb 1A +++,R - +++,R +++ - - - lowCarbaryl 1A +++,R - + ? +++,R +++,R + highChlorpyrifos 1B +++,R + + - + +++,R +++,R highDiflubenzuron 15 ++ +++,R +++,R - +++,R - - lowDimethoate 1B +++ - - - ? +++,R + highFenbutatin oxide 12 - - +++,R +++,R - - - lowFenpropathrin 3 +++,R - + + +++,R - + highImidacloprid (soil application, nonbearing)

4 +++,R +++,R - - + ++ + low

Imidacloprid (foliar application)

4 +++,R + - - - ++ + medium

Petroleum oil NR + ++,R ++,R ++ +(eggs) ++,R + lowPhosmet 1B +++ - + ? +++,R ? ? medium/highPyridaben 21 - ? +++,R +++,R - - - highSpinosad 5 - +++,R - - - - - lowSpinetoram 5 +++ +++,R - ? ? ? ? lowSpirodiclofen 23 - - +++,R +++,R ? - - lowSulfur NR - - +++,R +++ - ? ? high (short term)1Mode of action class for citrus pesticides from the Insecticide Resistance Action Committee; NR = no resistance potential(R) = product recommended for control of pest in Florida Citrus Pest Management Guide(+++) = good control of pest(++) = short-term control of pest(+) = low levels of pest suppression(-) = no observed control of pest(?) = insufficient data available

List of insecticides and miticides recommended for use in the Florida Citrus Pest Management Guide and their effects on citrus pests and their natural enemies

For more information, contact the University of Florida, IFAS, Citrus Research and Education Center 863-956-1151, www.crec.ifas.ufl.edu, or your local county citrus extension agent.

Created by: Michael E. Rogers, revised August 2008

Photo Credit: University of Florida

Tree Height Rate Product/A* Applications per season Ounces per tree Trees per ounceImidacloprid 2F2 ft – 4 ft 8 fl oz 4 0.057 fl oz 17.5 trees4 ft – 6 ft 16 fl oz 2 0.114 fl oz 8.77 treesImidacloprid 4.6F (Admire PRO)2 ft – 4 ft 3.5 fl oz 4 0.025 fl oz 40 trees4 ft – 6 ft 7 fl oz 2 0.05 fl oz 20 trees*Rates based on 140 trees per acre

Imidacloprid soil drench rates for solid plantings on nonbearing citrus

Active Ingredient Restricted entry interval (REI) Pre-harvest interval (PHI)Abamectin 12 hours 7 daysAcetamiprid 12 hours 7 daysAldicarb 48 hours 0; 30 days lemonsCarbaryl 12 hours 5 daysChlorpyrifos 5 days 21 daysDiflubenzuron 12 hours 21 daysDimethoate 48 hours 15 daysFenbutatin oxide 48 hours 7 daysFenpropathrin 24 hours 1 dayImidacloprid 12 hours 0Phosmet 24 hours 7 daysPyridaben 12 hours 7 daysSpinosad 4 hours 1 daySpinetoram 4 hours 1 daySpirodiclofen 12 hours 7 daysSulfur 12 hours 0Use pesticides safely. Read and follow directions on the manufacturer’s label.

Restricted Entry Interval (REI) and Pre-Harvest Interval (PHI) for products listed on front page

Additional citrus pest management information can be found in the Florida Citrus Pest Management Guide available online at http://www.crec.ifas.ufl.edu/extension/pest/index.htm

AcknowledgementsAcknowledgements

• Florida Citrus Production Research Advisory Council

• Citrus Growers (numerous)

• Florida Citrus Production Research Advisory Council

• Citrus Growers (numerous)

AcknowledgementsAcknowledgements• Lab Members:• Lab Members:

Harry AndersonSr. Biol. Sci.

Percivia “Peaches” MarinerResearch Assistant

Rhonda SchumannSr. Chemist

Dalia ShawerResearch Assistant

Tim EbertPost-doctoral

Research Assoc.

Antonios TsagkarakisPost-doctoral

Research Assoc.

Rosana SerikawaPh.D. Student