Economic Thresholds & IPM Strategy Dewey M. Caron University of Delaware

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)

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! We are management specialists!

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

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

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

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

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 #

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

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

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

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

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

SOLUTION?

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

EIL ET Average density Time Pest density Economic Threshold Apply controls Avoid exceeding economic injury level

Mite Numbers Increase seasonally

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

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

IPM THRESHOLD M onitoring 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

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

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

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

IPM Mite Control Triangle

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

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

Varroa Mites – physical control Screened bottom board

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

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® Thymol Api Life VAR® [thymol + others]; ApiGuard® Others -thyme, citronella, clove, camphor, eucalyptol Others -thyme, citronella, clove, camphor, eucalyptol Semiochemcials – Nasanov gland pheromones + others Mineral/vegetable oil (FGMO), esters Grease patties; oil machines, Sucrocide ® Grease patties; oil machines, Sucrocide ® Drying agents Diatomaceous earth, talc, powdered sugar Diatomaceous earth, talc, powdered sugar

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