Submitted to: Apidologie
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/6/2015
Publication Date: 12/2/2015
Citation: Danka, R.G., Harris, J.W., Dodds, G.E. 2015. Selection of VSH-derived Pol-line honey bees and evaluation of their Varroa-resistance characteristics. Apidologie 47(3):483-490. Interpretive Summary: A desirable approach to addressing the problem of Varroa mites is to breed bees for enhanced resistance to the mites. Some mite-resistant honey bees have been developed and are being used by beekeepers. It is clear, however, that many beekeepers, especially by large-scale commercial beekeepers, desire more functional mite-resistant bees which are suitable to their established management practices. We developed a new population by crossing bees with the mite-resistance trait Varroa sensitive hygiene (VSH) to bees used in in commercial beekeeping production. We then selected colonies based on good beekeeping functionality (survival, colony population, honey production) and apparent mite resistance (end-of-season infestation). Testing and selection occurred annually during 2008-2014 in collaboration with one to three beekeeping companies. The selected population was given the name “Pol-line” honey bees. We then compared Pol-line bees and the parental VSH bees for characteristics related to resistance to Varroa mites. The two bee types did not differ in the amount of infested brood they removed, or in the frequency of non-reproduction among the mites that remained. We conclude that relatively simple field selection that focused on low end-of-season mite infestations in colonies having VSH introgressed into commercial beekeeping stock shows promise in creating bees with useful mite resistance and desirable beekeeping characteristics. This approach using selection methods appropriate for use by commercial bee breeders may encourage adoption and further selection of mite-resistant bees.
Technical Abstract: Honey bees, Apis mellifera, that have high expression of the trait “Varroa sensitive hygiene” (VSH) have good resistance to Varroa destructor. We selected “Pol-line” bees by outcrossing VSH queens in three U.S. commercial beekeeping companies annually during 2008-2014 and selecting colonies with the lowest mite infestations and adequate adult bee populations. Beginning in 2011, queens of previously selected Pol-line bees also were outcrossed, and performance of their colonies was compared to colonies with outcrossed VSH queens. Mite infestations after one season in Pol-line colonies usually were equal to or less than those in colonies having outcrossed VSH queens. Queens from the most functional colonies of both bee types were added to the Pol-line breeding population when bees were propagated each year. Mite resistance indicated by field tests was investigated further by exposing mite-infested brood to Pol-line and VSH colonies for one week. The two bee types did not differ in the amount of infested brood they removed, or in the frequency of non-reproduction among the mites that remained. Relatively simple field selection that focused on low end-of-season mite infestations in colonies having VSH introgressed into commercial beekeeping stock shows promise in creating bees with useful mite resistance and desirable beekeeping characteristics.