Varroa destructor remains one of the primary causes of honey bee decline worldwide. Beekeepers continue to look for alternative methods to control this parasite. Varroa mites can quickly evolve resistance to synthetic acaricides, such as couma-phos and fluvalinatc (Elzen et. al. 2002; Milani et. al. 1999). Residues of these synthetic acaricides are usually found in wax and pollen, increasing the frequency of bees exposed to these toxic chemicals. Thus, natural compounds that have low toxicity to becsand do not accumulate in wax are being used more often to control varroa mites (Imdorf et al., 1997). These compounds include organic acids, such as oxalic and formic acid, and essential oils, such as a thymol. Both formic acid (active ingredient in Mite-Away Quick Strips") and thymol (active ingredient in Apiguard~R and ApiLifeVar") have been legal in the US for quite a few years, but their efficacy is highly dependent upon ambient temperature. Moreover, these chemicals can have negative effects on brood and queen health. Oxalic acid (OA) has been used for many years by beekeepers in Europe and Canada, but was legalized in the US only in 2015. OA is an organic acid commonly found in plants and honey, and it is employed in the domestic sector as a household cleanser or wood bleach. Its efficacy against varroa mites can reach 90, it is naturally found in honey (Bogdanov et al 2002), and due to its hydrophilie properties, it is not expected to accumulate in beeswax (Rademacher and Harz 2006). All of these characteristics make OA a desirable chemical for mite control.
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