Synthetic and natural acaricides impair hygienic and foraging behaviors of honey bees

Acaricides commonly used to control the honey bee parasitic mite, Varroa destructor, may also adversely affect bees. Sublethal LD05 doses of synthetic (tau-fluvalinate, amitraz, and coumaphos) and natural (thymol and formic acid) acaricides did not significantly reduce bee survivorship. However, compared to the ethanol solvent control, hygienic behavior critical for pathogen and parasite control was significantly reduced with coumaphos, whereas both pollen and non-pollen foraging behaviors critical for resource acquisition were reduced with tau-fluvalinate, coumaphos, and formic acid. Thymol significantly reduced non-pollen foraging but also reduced the negative effects of ethanol on hygienic behavior. Amitraz did not affect hygienic and foraging behaviors relative to the solvent. Thymol and amitraz appeared to be the safest acaricides based on these tests.