An Investigation of Techniques for Using Oxalic Acid to Reduce Varroa Mite Populations in Honey Bee Colonies and Package Bees

I performed laboratory bioassays to characterize the acute contact toxicity of oxalic acid (OA) to Varroa destructor (Anderson & Trueman) and their honey bee hosts (Apis mellifera). Specifically, I conducted glass-vial residual bioassays to determine the lethal concentration of OA for Varroa, and I conducted topical applications of OA in acetone to determine the lethal dose for honey bees. The results indicate that OA has a low acute toxicity to honey bees and a high acute toxicity to mites. The toxicity data will help guide scientists in delivering optimum dosages of OA to the parasite and its host, and will be useful in making treatment recommendations. The data will also establish a baseline for OA susceptibility for both parasite and host to compare with future populations if Varroa mites exhibit resistance to OA. Introduction The objective of this study was to characterize the acute contact toxicity of OA to Varroa mites and their honey bee hosts in laboratory bioassays. Only one study has quantified the contact toxicity of OA to Varroa mites collected from brood cells (Milani 2001), and the contact toxicity of OA to honey bees has not been determined. One