The kin recognition system of carpenter ants (Camponotus spp.)

Abstract

Previous investigations of small colonies (<10 workers each) of Camponotus spp. indicated that queen-derived recognition cues, transferred to and learned by workers, are of major importance in between-colony discrimination (Carlin and Holldobler 1983, 1986). However, queens may have contributed disproportionately to a communal label or “gestalt” in small colonies. Here we report experiments on groups of approximately 190 sister workers of C. floridanus, adopted to alien conspecific queens. In 1200 neutral arena encounters, adoptees were introduced to their own unfamiliar sisters, reared in their colony of origin; unfamiliar non-sisters were introduced as controls. Following tests of worker behavior, the queens were dissected. Aggression was equally strong in encounters between unfamiliar kin and encounters between nonkin, if the adoptive queen had fully-developed ovaries, was completely inseminated, and produced abundant brood. However, workers were significantly less aggressive in encounters between kin if their queens had less active ovaries and were incompletely inseminated. Thus the presence of a fully functional queen continues to prevent recognition of unfamiliar kin in larger colonies, but worker cues can become more important when the queen is ineffective. In addition, adoptees of productive queens were significantly less aggressive toward pure-colony sisters than the latter were to them, suggesting the involvement of a foreignlabel rejection mechanism (Getz 1982).