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Simple Summary: One of the main culprits of honey bee colony losses is the parasitic mite, Varroa destructor, which is primarily controlled with acaricides, which lose efficacy due to resistance and can contaminate honey. An alternative is to breed bees that are resistant to Varroa, which was conducted in this study by bidirectional selection for mite fall to obtain colonies with low (resistant) or high (susceptible) Varroa population growth (LVG and HVG, respectively). Selection for three generations resulted in greatly reduced Varroa population growth in LVG compared to HVG colonies. In addition, Varroa infestation rates of bees were lower in LVG colonies, and they had lower Deformed Wing Virus (DWV) infection levels. Survival of Varroa-parasitized bees was higher for LVG bees compared to HVG bees, which may help explain why colony winter survivorship was higher for LVG colonies than for HVG colonies. Selecting colonies of bees for LVG resulted in better individual and colony bee health, demonstrating its effectiveness as a means of breeding for controlling Varroa mites. Honey bee (Apis mellifera) population declines have been associated with the parasitic mite, Varroa destructor, which is currently primarily controlled by the use of acaricides. An alternative is to breed for resistance to Varroa, which was conducted in this study by bidirectional selection for mite fall to obtain colonies with low (resistant) or high (susceptible) Varroa population growth (LVG and HVG, respectively). Selection for three generations resulted in approx. 90% lower Varroa population growth in LVG than in HVG colonies. In addition, late summer Varroa infestation rates of brood and adults were both significantly lower in LVG colonies (p < 0.01), which was also significantly associated with lower Deformed Wing Virus (DWV) infection levels (p < 0.01). Survival of Varroa-parasitized bees was almost 50% higher for LVG bees compared to HVG bees (p < 0.01). Also, colony winter survivorship was significantly higher for LVG colonies than for HVG colonies (p < 0.05). However, the higher colony populations observed for LVG colonies were not significantly different from those of HVG colonies. Overall, individual and colony health was improved by selecting colonies for LVG, demonstrating its effectiveness as a means of breeding for controlling Varroa populations in honey bee colonies. [ABSTRACT FROM AUTHOR] |
