Entomology Research Updates Psyllid transmission of greening and chemical control of psyllids

1. Entomology Research UpdatesPsyllid transmission of greening and chemical control of psyllids Michael E. Rogers UF / IFAS / Citrus Research and Education Center, Lake Alfred

2. 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

3. Psyllid Acquisition Rates (laboratory studies) • Psyllids which fed as adults on HLB (+) plants • Average acquisition rate of 20-30% Greening Infected Adult Psyllids % infected Feeding Time (days)

4. 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%

5. Psyllid Acquisition Rates (field studies) • Caging Studies • Acquisition by adults vs nymphs

6. 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

7. Seasonal 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

8. Preliminary Data (Jan-Jul 2008) 4500 4000 3500 3000 Psyllid Infection rate and sample size averaged for all Florida sites. 2500 2000 1500 0.5% Total # psyllids sampled 1000 Infection Rate Sample Size (N) 500 0 Jan Feb Mar Apr May Jun Jul Aug 0.2% 0.006 0.005 Small sample size 0.004 0.003 • 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 0.002 0.001 0

9. Summary 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

10. Summary 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

11. 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?

12. Vector Management using insecticides • Preventing transmission • Reducing overall psyllid populations

13. 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?

14. Ongoing studies: • imidacloprid treated and untreated plants challenged with HLB (+) psyllids

15. 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

16. Huh?!?

17. Electrical Penetration Graph (EPG) – measure psyllid feeding

18. EPG 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

20. Control of Asian citrus psyllid, citrus leafminer and citrus rust mite Trial 2008-10 M.E. Rogers UF / IFAS / Citrus Research & Education Center, Lake Alfred

21. Treatments

22. 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%)

31. 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

32. Imidacloprid soil drench rates for solid plantings on nonbearing citrus 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

33. Acknowledgements • Florida Citrus Production Research Advisory Council • Citrus Growers (numerous)

34. Acknowledgements • Lab Members: Harry Anderson Sr. Biol. Sci. Percivia “Peaches” Mariner Research Assistant Rhonda Schumann Sr. Chemist Dalia Shawer Research Assistant Tim Ebert Post-doctoral Research Assoc. Antonios Tsagkarakis Post-doctoral Research Assoc. Rosana Serikawa Ph.D. Student