Female mate choice in the carpenter bee Xylocopa varipuncta (Hymenoptera: Anthophoridae)



Females of the carpenter bee Xylocopa (Neoxylocopa) varipuncta Patton exhibit highly active mate choice. During the spring in central Arizona, males of this species hover at shrubs and trees on or near ridgelines in late afternoons. Occasionally, females fly to and closely approach pheromone-releasing males on their territories, but in 65 of 85 approaches the female left without copulating. Some females visited several males in a few minutes. Copulation only occurred when the female landed on a spot that the resident male rubbed with his body upon the female's arrival. Males did not attempt to disrupt courtship or copulation by other males. In 1988 one creosote bush proved especially attractive to males, as measured by the frequency with which the site was occupied simultaneously by more than one male. The majority of close approaches by females occurred in this one bush. Simultaneous occupation of hovering sites was very rare in 1989. In this year, there was a weak but significant correlation between the frequency with which different sites were visited by intruder males and by females. These results support the hypothesis that males are able to identify locations most likely to attract potential mates.