Mating frequencies of Africanized honey bees in the southwestern United States

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 southwestern 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 ± 6.53 (range 10 – 32) drones, resulting in effective paternity frequencies of 20.0 ± 8.46 (range 10.56 – 37.53), which constitutes one of the highest mating numbers recorded within the species. Though Africanized honey bee colonies are among 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.