Meeting Abstract
The Eastern Carpenter Bee, Xylocopa virginica, usually lives in small colonies of 2-6 females. Nestmates form reproductive queues in which the dominant female monopolizes both foraging and reproduction. A few females postpone reproduction, remaining in the natal nest as subordinate guards, thus assisting the dominant bee. In return, subordinate females are fed by dominants. Reproductive queues change over time, as females die, their positions are usurped, or when they move to new nests. Experimental evidence indicates that female carpenter bees are good at discriminating nestmates from non-nestmates, being more aggressive to non-nestmates and more peaceful with nestmates. Since social recognition in insects is thought to be based on the cuticular hydrocarbon profiles of individuals and colonies, we used GC-MS to assay the hydrocarbon profiles of 68 females that were also genotyped at 9 microsatellite loci. Analyses based on principal components and discriminant functions indicated that individual odours provide sufficient information to discriminate nestmates from non-nestmates, and that nestmates tended to have similar profiles. Microsatellite analyses indicated that most nestmates were unrelated. Taken together, these results imply that chemical profiles reflect residence, not kinship. This in turn means that nestmate recognition and discrimination against non-nestmates must be based on familiarity, rather than on kin relationships. Since nestmates cooperate as well as compete with each other, this is evidence that nestmate recognition based on individual odours facilitates cooperation among non-kin that breed cooperatively. Eastern Carpenter Bees may be the first example of a social bee society based on reciprocity.
