New paper

The varroa mite (Varroa destructor Anderson and Trueman) is a devastating pest of honey bees (Apis mellifera L.). Beekeepers have relied on the pyrethroid pesticide tau-fluvalinate as a principal agent of varroa mite control. While this miticide was quite effective at controlling varroa mites through the 1990s, its efficacy has waned as resistance to tau-fluvalinate has appeared in many populations of mites. Resistance in some populations of varroa mites has been associated with elevated detoxification of tau-fluvalinate. Honey bees tolerate miticidal tau-fluvalinate applications principally through rapid detoxification mediated by cytochrome-P450 mono-oxygenases, with the other detoxification enzyme families, the carboxylesterases and glutathione-S-transferases, playing much smaller roles in miticide tolerance. The goal of this study was to test the capability of the glutathione-S-transferase enzyme inhibitors diethyl maleate and curcumin, which should interfere minimally with honey bee detoxification, to elevate the toxicity of tau-fluvalinate to a population of varroa mites. Additionally, to test the role of cytochrome P450s and esterases in any detoxification-mediated resistance, varroa mites were also treated with the enzyme inhibitors piperonyl butoxide and S,S,S-tributyl phosphorotrithioate. None of the tested enzyme inhibitors increased the toxicity of tau-fluvalinate, suggesting that detoxification plays a minimal role in the tolerance of tau-fluvalinate in the population of varroa mites in this study.