New work on varroa control from the USDA, ARS
While miticide applications are typically the most
consistent and efficacious Varroa mite management method, miticide-induced insecticide synergism
in honey bees, and the evolution of resistance in Varroa mites are reasonable concerns. We treated
colonies with the miticide amitraz (Apivar®), used IPM practices, or left some colonies untreated
Thirty-six colonies of Italian honey bees (Wooten’s Golden Bees, Palo Cedro, CA, USA) were
established in single-story deep Langstroth hives on 4 May 2015 at the USDA-ARS (United States
Department of Agriculture, Agricultural Research Service) Honey Bee Breeding, Genetics, and
Physiology Laboratory in Baton Rouge, LA, USA, under normal field rearing conditions.
While our seasonal mite management experiments were terminated in October, we originally
planned to continue them through December. However, the control and IPM colonies in October
displayed a high frequency of overt symptoms of deformed wing virus (DWV) and chronic bee
paralysis virus (CBPV), presumably due to high mite infestation in those treatment groups.
The current Apivar® label limits application to 2 treatments annually with a 56 days maximum treatment interval. Amendment of the Apivar® label to allow uninterrupted year-round treatment would very likely improve product effectiveness in the short term. However, a constant treatment regime would also increase selection pressure for amitraz resistance in Varroa mites. The loss of effective amitraz treatments to control Varroa mites is a disconcerting prospect due to the low rate of product development to specifically and effectively control Varroa mites.
Rinkevich, F. D., Danka, R. G., & Healy, K. B. (2017). Influence of Varroa Mite (Varroa destructor) Management Practices on Insecticide Sensitivity in the Honey Bee (Apis mellifera). Insects, 8(1), 9.
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