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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Bee Research Laboratory » Research » Research Project #442009

Research Project: Integrated Control of Varroa Mites at the USDA-ARS Bee Research Laboratory

Location: Bee Research Laboratory

Project Number: 8042-21000-291-058-I
Project Type: Interagency Reimbursable Agreement

Start Date: Mar 1, 2022
End Date: Sep 30, 2022

The goal of the research is an integrated effort against Varroa mites using our expertise in honey bees, mite biology, virology, and chemical ecology. Three distinct objectives are: 1) Refine understanding of Varroa mite ecology, including the roles of chemical cues that direct mite movements among colonies; 2) Identify the roles of seasonality and mite/host physiology underlying variable susceptibility of Varroa mite to toxicants; and 3) Testing potentially novel chemical varroacides in laboratory and field-level experiments.

For Objective 1, the focus will be on understanding whether and how colony mite loads, which may be correlated to levels of in-hive chemical cues, affect movements of mites among colonies. A hypothesis for this work states there will be a net emigration of mites from colonies with lower mite loads and net immigration of mites to colonies having higher mite loads. For Objective 2, we will use established toxicological methods to determine the Varroa mite LC50 for key varroacides, including amitraz, fluvalinate, and coumaphos at several points over the spring/summer and fall/winter seasons. At these same time points, we will determine the antioxidant capacity, activities of several antioxidant/detoxification enzymes, and the expression of the genes producing these enzymes for both the mites and their honey bee hosts. We will also quantify the levels of host-derived proteins (vitellogenin, heat shock proteins, etc.) in both hosts and mites, and use these data as explanatory variables in analyses of the mites’ response to chemical exposure. For Objective 3, we will use standard toxicological methods to run vial and jar vessels bioassays exposing mites and bees, respectively, to toxicants applied to the inner surfaces of vessels, and gauge mite and bee mortality at several points over 48 hours. Next tier, cage bioassays, which include bees together with their mite parasites, will also be run to gauge effect of toxicants in a ‘bug on a bug’ scenario. Field level experiments will use 10-15 full-size field honey bee colonies per treatment (three treatments total: positive and negative treatments, and the test treatment. Standard methods for running field experiments with honey bees will be followed. Data on treatment efficacies via measured mite levels in colonies, as well as bee-relevant data, such as brood and adult populations, will be collected at several points over a 42-day period.