Economic Thresholds & IPM Strategy

1. EconomicThresholds&IPMStrategy Dewey M. Caron University of Delaware

2. IPM – Integrated Pest Management “Several techniques are employed simultaneously to solve specific pest problems” I=INTEGRATED – ideally use of more than pesticide chemical control P=PEST – mites sure but applicable to any of the 3 P’s M=MANAGEMENT – as you mange the bee population you manage the P’s Alternative BMP’s Best Management Practices names: Alternative Treatments (non-pesticide)

3. IPM • IPM is a decision-making process for control of PESTS • PEST = pathogens, parasites, predators of honey bees, their colonies &/or products • Bee Mites have changed the face of beekeeping – no longer bee-havers • We are management specialists!

4. Four Fundamental Strategies for Pest Management • Do nothing • Reduce numbers of pest • Reduce susceptibility of the host • Use combinations of the last two

5. Goals to Focus on When Developing a Pest Management Plan • Reduce pest status • Conserve environmental quality • Accept tolerable pest densities • Improve net profits • Timing…NOT calendar treatments

6. Implementation of Pest Management Strategies • Pest identification • Pest population assessment • Economic evaluation* • Timing of controls * Is economic damage possible/imminent?

7. How to Achieve These Goals • Efficient sampling methods • Valid decision guidelines • Integrating a number of effective tactics for an overall plan of attack • Acceptance of higher mite levels

8. IPM in Practice • MONITORING Mite levels fluctuate within & between seasons. We must carefully sample (=scout or monitor) and then use best estimates to determine risk level – if risk elevated we control! We MUST - Understand bee/mite life cycle - be able to ID mite & predict #

9. Varroa mite – a pest or vector? K-Wing or Wingless bees of value?

10. Adult female mite enters larval cell as it completes development. She hides on side wall as pre-pupa spins cocoon Illustration series from Martin IN: Mites of Honey Bees Dadant & Sons, Inc 2001

11. In 60 hours she lays 1st egg (male). After 24 hours she lays female egg one every 24 hours

12. Her son (male) develops feeding on pupa & mates w/ sister as she matures

13. When adult bee emerges 1.3 adult female mites are mature – if eggs on drone 3X are mature

14. SOLUTION?

15. Control Collapse w/ Pesticides “Resistant” mites increase with each generation Due to: (1)selection pressure (2)Sub-optimal exposure

16. Economic Threshold 80 Avoid exceeding economic injury level 70 EIL 60 Apply controls 50 Pest density ET 40 Averagedensity 30 20 10 0 Time

17. Mite Numbers Increase seasonally

18. Mite Numbers High mite yr Low mite yr Vary between colonies & years

19. Monitoring • On brood - worker - drone • On bees - ether roll - powdered sugar - alcohol wash • In colony - Sticky board

23. IPM THRESHOLDMonitoring can supply a number - a “guesstimate”One or more numbers can be obtained - use number(s) to evaluate mite population- one mite in sample = X mites in colony(1=50 in U.S. -- 1=100 Europe)Determine an appropriate risk level- one mite vs 100 vs 1000?Assumption: 3000 mites in fall represents a minimally acceptable conservative risk???Balance of costs vs benefits

24. Valadation of mite sample [bars] to actual numbers [background] Not perfect but good correlation

25. Threshold • An acceptable level of pests [mites] – determine necessity of further controls • A number to use to evaluate mite control efficacy efforts • Allows estimation of risk if no pesticide chemical is integrated into the control • The basis for IPM – a decision process utilizing modern pest control practices

26. Threshold • Spring/summer (April or May or Mid-June) • Sticky boards – over 5-10 • Adult bees – over 3-4 • Brood – over 5% Exceeding threshold means additional control may be useful Pre-fall (mid-August, Sept too late!) • Sticky boards – over 50-60 means additional control • Adult bees – over 10-12 • Brood – over 5-10% Exceeding threshold means additional (chemical) control needed

27. IPM Mite Control Triangle

28. Varroa Mites – cultural control • Apiary site location • Comb culling • Small-sized cell base • Requeening w/ Resistant (tolerant) stock • Hygienic queen stock • SMR (surpressed mite resistance) • Russian stock From Martin: In Mites of the Honey Bee

29. Varroa Mites – physical control • Screened bottom boards (season long) • Drone brood trapping (1X to 8X) • Heat (104-110◦F for 4 hrs)

30. Varroa Mites – physical control Screened bottom board

31. Varroa Mites – biological control • No identified control agent so far • Best choice seems to be a virus or fungus

32. Varroa Mites – Chemical control • Miticides - Apistan®; Checkmite+®; Amitraz® • Formic acid - Apicure®; Mite-Away II® • Other acids (acetic; oxalic) • Essential oils • Thymol Api Life VAR® [thymol + others]; ApiGuard® • Others -thyme, citronella, clove, camphor, eucalyptol • Semiochemcials – Nasanov gland pheromones + others • Mineral/vegetable oil (FGMO), esters • Grease patties; oil machines, Sucrocide ® • Drying agents • Diatomaceous earth, talc, powdered sugar

33. Varroa Mites - Chemical Control • Pesticides – natural/synthetic need to be approved (registered) for legal use • Emergency registration (i.e. Checkmite+) means emergency – temporary answer • Natural doesn’t mean less toxic • DUMB chemicals (less toxic, not pre-packaged) need SMART beekeepers