Behavioral Interactions of Two Solitary,Halictine Bees with Comparisons among Solitary,Communal and Eusocial Species

Laboratory behavioral experiments were conducted with two solitary, halictine bee species, in the genus Lasioglossum, to examine the nature of behavioral interactions between non-nestmate females. The experimental design of this study was identical to previous work on both a communal (Kukuk 1992) and a eusocial Lasioglossum species (Breed et al. 1978), thereby providing data for comparison of female-female interactions in species within a single, very large genus that exhibit different sociality. Both solitary species exhibited low levels of aggressive behavior yet nearly all females were reproductively active, as determined by subsequent dissections. Neither ovarian width nor size was associated with aggression in either species. Interspecific comparisons reveal large differences in cooperation and aggression among the four congeneric species. The communal species exhibits significantly more cooperative and less aggressive behavior than all other species suggesting that communal social behavior in Lasioglossum is not phenetically intermediate between the behavior of solitary and eusocial species.