Submitted to: Journal of Apiculture Research
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/20/2010
Publication Date: 10/20/2010
Citation: Tarpy, D., Caren, J.R., Delaney, D.A., Sammataro, D., Finley, J.V., Loper, G., Hoffman, G.D. 2010. Mating frequencies of Africanized honey bees in the southwestern United States. Journal of Apiculture Research. Vol. 49(4):302-310. Interpretive Summary: There is substantial evidence that colonies headed by queens that have mated with many drones and thus have many patrilines are healthier and can tolerate diseases and mites far better than colonies where there are fewer patrilines. We examined the number of drones that European and African queens mated with to determine if the success of African bees in displacing Europeans could be attributed to greater numbers of patrilines in African colonies. Using molecular genetic techniques that involved microsattelite markers, we found that African queens mated with an average of 20 drones. This is similar to what has been reported for African bees in Africa. The European queens we examined had similar mating numbers. The results indicate that there was not selection pressure on African bees to increase or decrease their mating number when they established in the western hemisphere and the benefits from increased patriline number did not contribute greatly to the successful establishment of African bees in the New World.
Technical Abstract: Colony genetic diversity may be a key factor in determining the ecological success of invasive social insects. Emerging evidence suggests that there are significant adaptive advantages conferred to genetically diverse colonies (either through multiple queens or multiple mates by queens). Here we determine the intracolony genetic diversity of Africanized honey bee (AHB) colonies sampled from a feral population in the southwetern U.S. We genotyped a total of 1,253 worker offspring from 18 feral AHB, four managed AHB, three managed EHB, and four control colonies (headed by EHB queens instrumentally inseminated with one, two, five, or ten drones) using eight microsatellite markers. We found that the feral Africanized honey bee queens mated with an average of 20.0 plus or minus 6.53 (range 10-32) drones, resulting in effective paternity frequencies of of 20.0 plus or minus 8.46 (ranage 10.56-37.53), which constitutes the highest mating numbers yet recorded within the species. Though Africanized honey bee colonies are the most genetically diverse Apis mellifera subspecies yet recorded, their queen mating frequencies are within the expected range of the species overall, including African honey bees in its native range. As such, our results do not support the hypothesis that Africanized honey bees have been subject to strong selection for increased (or decreased) intracolony genetic diversity. Increased mating frequencies by AHB queens and the associated colony fitness benefits that increased genetic diversity may manifest probably do not contribute greatly to the ecological dominance of this invasive social insect.