The relationship between hygienic behavior and suppression of mite reproduction as honey bee (Apis mellifera) mechanisms of resistance to Varroa destructor

We compared the mechanisms of resistance to Varroa destructor displayed by bees bred for Suppression of Mite Reproduction (SMR) and hygienic behavior (HYG). Mites from SMR and HYG source colonies were introduced into recently sealed SMR and HYG worker brood, and the infested pupae were placed either into recipient colonies or into an incubator. SMR colonies removed significantly more miteinfested pupae than the HYG colonies. The reproductive success (fertility and number of viable female offspring) of mites from both sources on pupae not removed by bees was significantly lower in SMR colonies. Within the incubator, the reproductive success of mites was also lower on SMR worker pupae, and lowest when mites from SMR colonies were introduced on SMR brood. Our findings indicated that bees bred for SMR express hygienic behavior; adult bees selectively remove pupae infested with mites. In addition, there is an effect of SMR pupae that reduces mite reproductive success that requires further investigation.