Kin Association in the Allodapine Bee Exoneura richardsoni Rayment (Hymenoptera Apidae)

Exoneura richardsoni is a common allodapine bee which, in southern montane Victoria, primarily nests in dead fronds of tree ferns. We sampled intact colonies from the Dandenong Ranges from August 1992 through to February 1993. The bee is univoltine, with egg production commencing in later winter and adult eclosion occurring over summer. The majority of colonies in both re-used and newly founded nests contain more than one female. Intra-colony relatedness is very high (r = ± s.e., 0.759 ± 0.087) in re-used nests and moderately high (0.498 ± 0.152) in newly cofounded colonies, indicating maintenance of kin integrity during nest re-use and kin recognition during foundress association. This is only the second time that kin cofounding has been demonstrated in a primitively social bee species. Samples during winter and early summer show that per capita brood production increases with colony size up to about 3 or 4 females per nest, and this may explain the high degree of social nesting in this species. Whilst eusociality could occur in some nests, the opportunities for older, adult brood members to help rear younger siblings are very limited. It seems likely that in E. richardsoni and at least some other Australian allodapine bees, the selective maintenance of high levels of social nesting and kin recognition does not depend on the existence of eusociality.