1. IPM Strategy for Varroa Mites Lance Cuthill
Slide Info and Background:
Dewey M. Caron
University of Delaware

2. IPM – Integrated Pest Management
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
“Several techniques are employed simultaneously to solve specific pest problems”

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 Varroa 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 Varroa Management Plan
Reduce pest status
Accept tolerable pest densities
Improve net profits
Timing…NOT calendar treatments

6. Implementation of Varroa 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?

10. enters larval cell as it completes development. She hides on side wall
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 EIL ET Pest density Average density Time 80 70 60
Avoid exceeding economic
injury level 70
EIL 60
Apply controls 50
Pest density ET 40
Average density 30 20 10
Time

17. Mite Numbers
Increase seasonally

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

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

23. IPM THRESHOLD Monitoring 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 Determine an appropriate risk level - one mite vs 100 vs 1000? Assumption: mites in fall represents a minimally acceptable conservative risk??? Balance of costs vs benefits
Basics of the rational of IPM. It assumes a pest situation (host honey bee) can function with some base level of pests (mites) and still function normally. We determine a threshold, test the threshold and then can assign some level of risk to exceeding the threshold level of pests.

24. 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

25. 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 means additional control
Adult bees – over 10-12
Brood – over 5-10%
Exceeding threshold means additional (chemical)
control needed

26. IPM THRESHOLD Monitoring 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 Determine an appropriate risk level - one mite vs 100 vs 1000? Assumption: mites in fall represents a minimally acceptable conservative risk??? Balance of costs vs benefits
Basics of the rational of IPM. It assumes a pest situation (host honey bee) can function with some base level of pests (mites) and still function normally. We determine a threshold, test the threshold and then can assign some level of risk to exceeding the threshold level of pests.

27. 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

28. 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 means additional control
Adult bees – over 10-12
Brood – over 5-10%
Exceeding threshold means additional (chemical)
control needed

29. IPM Mite Control Triangle

30. 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
Cultural control is less interventive and non-chemical type of approach. Each of the alternatives have been shown to offer some level of control but must be used skillfully.
From Martin: In Mites
of the Honey Bee

31. Varroa Mites – physical control
Screened bottom boards (season long)
Drone brood trapping (1X to 8X)
Heat ( ◦F for 4 hrs)
Physical control is use of traps or devices (something physical) and is non-chemical. The top two are effective but vary widely in amount of effort needed – drone trapping is lots of work.

32. Varroa Mites – physical control
Screened bottom boards are about 10-20% effective depending upon circumstances. The bottom screens can be left on colonies year-round but requeening and smaller nuc colonies do not do as well with open screen bottoms. The debris that falls below the bottom screen is an ideal location for development of hive pests so they must be incorporated into a management system.
Screened bottom board

33. Varroa Mites – biological control
No identified control agent so far
Best choice seems to be a virus or fungus
Biological control (biocontrol) has not yet been shown to be feasible. Varroa mites are susceptible to a fungus and a nematode is found in the mites but neither have yet been utilized into effective management for control.

34. 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
Chemical control is therefore usually necessary once mite populations exceed threshold levels (measured in mid-August) if colonies are to overwinter and be healthy to expand in the spring buildup. Chemical control can utilize various types of chemicals from relatively non-toxic (to host, applicator and sometimes to pest too) such as drying agents (bottom of list) to chemicals sold as killers (XXXcides=killers)

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