EFFECTS OF SYNTHETIC AND ORGANIC ACARICIDES ON HONEY BEE HEALTH: A REVIEW

The honey bee is a crucial pollinator of agricultural crops and also an economically important producer of commodities such as honey and beeswax that find diverse uses in the food industry, cosmetics and medicine. At present, the ectoparasitic mite Varroa destructor is viewed as the most damaging pest of the honey bee worldwide. Without treatment, colonies generally collapse within a few years. To keep the population of the Varroa mites low, beekeepers relay on the use of synthetic and organic acaricides, the most popular commercially available ones include amitraz, coumaphos, flumethrin, fluvalinate, formic acid, oxalic acid and thymol. These conventional acaricides are cheap and easy to apply, but prolonged use causes Varroa mites to rapidly develop resistance and bee products can become contaminated. Residues of acaricides are present in high concentrations throughout the hive and bees are exposed to them all year around. The present review summarises the current knowledge of the deleterious effects of conventional acaricides on honey bee health. Numerous commercially available acaricides and their active substances have been shown to have negative effects on honey bee brood development, queen and drone reproductive health, learning, longevity and colony strength. Acaricides do not only act alone, but also in synergic combinations to affect bee health. Since some drugs cause substantial weakening of bee colonies, they can make them more susceptible to other diseases such as nosematosis or to extreme climatic events. As wax combs are contaminated with high concentrations of acaricide residues and Varroa mites are chronically exposed to them, the parasite may develop resistance faster. In combination with other stressors, acaricides could be a contributing factor to colony collapses.