Resistance pattern

The possibility of resistance emerging after several treatments should be monitored. The product applications should cover several reproductive cycles of the parasite to show the development of resistance and the rate of such development. Such studies can be performed under laboratory (see section 3.6.3. ‘Bioassays to quantify the susceptibility of the varroa mite to acaricides’) and/or field conditions. Not only mites, but also bees might develop resistance against miticides after regular use for several bee generations. This translates in a change in dose-lethality relationship of the product or active substance(s) and therefore affects the safety of the product for bees which increases. See the BEEBOOK paper on toxicology methods (Medrzycki et al., 2013) to evaluate miticide toxicity for honey bees.