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United States Department of Agriculture

Agricultural Research Service

Title: Population dynamics of Varroa destructor (Acari: Varroidae) in commercial honey bee colonies and implications for control

Authors
item Degrandi-Hoffman, Gloria
item Ahumada, Fabiana -
item Curry, Robert -
item Probasco, Gene -
item Schantz, Lloyd -

Research conducted cooperatively with:
item

Submitted to: Experimental and Applied Acarology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 30, 2014
Publication Date: May 15, 2014
Citation: Hoffman, G.D., Ahumada, F., Curry, R., Probasco, G., Schantz, L. 2014. Population dynamics of Varroa destructor (Acari: Varroidae) in commercial honey bee colonies and implications for control. Experimental and Applied Acarology. DOI 10.1007/s10493-014-9821-z.

Interpretive Summary: We devised different treatment schedules to maintain low levels of Varroa mites in honey bee colonies using the miticide HopGuard® (HG). We tested the treatment schedules in hives started from either package bees or splits of larger colonies. The schedules were developed based on predictions from a Varroa population growth model (VARROAPOP). In colonies started from package bees, Varroa populations were reduced to < 2.0 mites per 100 bees when HG was applied in the packages in the spring and again in the colonies during summer. In the fall, colonies treated in August had fewer mites than untreated colonies or those treated only in the spring. HG applications in colonies started from splits in April reduced mite populations to 0.12 mites per 100 bees. In September, the treated colonies had significantly fewer mites than the untreated controls. Subsequent HG applications in September that lasted for three weeks reduced mite populations to levels in November that were significantly lower than in colonies that were untreated or had an HG treatment that lasted for one week. The increases in Varroa populations from summer to fall that we measured in colonies established from package bees or splits were much greater than those predicted by the model which bases population growth on mite reproduction. One explanation for the differences might be that Varroa is immigrating into colonies in sufficiently high numbers to affect mite population growth. The implications for controlling Varroa in colonies if the mite is highly mobile are discussed.

Technical Abstract: Treatment schedules to maintain low levels of Varroa mites in honey bee colonies were tested in hives started from either package bees or splits of larger colonies. The schedules were developed based on predictions of Varroa population growth generated from a mathematical model of honey bee colony – Varroa population dynamics. The miticide we used was HopGuard® (HG). In colonies started from package bees, Varroa populations were reduced to < 2.0 mites per 100 bees when HG was applied in the packages in the spring and again in the colonies during summer. In the fall, colonies treated in August had fewer mites than untreated colonies or those treated only in the spring. HG applications in colonies started from splits in April reduced mite populations to 0.12 mites per 100 bees. In September, the treated colonies had significantly fewer mites than the untreated controls. Subsequent HG applications in September that lasted for three weeks reduced mite populations to levels in November that were significantly lower than in colonies that were untreated or had an HG treatment that lasted for one week. The increases in Varroa populations from summer to fall that we measured in colonies established from package bees or splits were much greater than those predicted by the model which bases population growth on mite reproduction. One explanation for the differences might be that Varroa is immigrating into colonies in sufficiently high numbers to affect mite population growth.

Last Modified: 11/28/2014
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