D3021: Surrogate species for Varroa destructor in acid bioassays

Varroa destructor is an ectoparasite that is the greatest threat to managed honey bee colonies worldwide. Resistance to traditional chemical controls requires continual testing of possible new acaricides. V. destructor, however, are difficult to obtain for use in control bioassays because they are obligate parasites that cannot be reared outside of a honey bee colony. We conducted several bioassays using other, more easily obtainable species to find an organism that could be used as a surrogate for V. destructor when testing new potential controls. We tested acetic, lactic, formic and oxalic acids at 0.005%, 0.05%, 0.5%, 5% and 50% concentrations for the control of two species of beetle (Oryzaephilus surinamensis and Alphitobius diaperinus), wax worm larvae (Galleria mellonella), and Varroa destructor. The assays were consistent across all species. Our results show that other organisms can be used in place of V. destructor for initial testing of new chemical controls of the ectoparasite. The assay also provided insight into the mode-of-action of various acids.