Division of labor in the neotropical ant, Pachycondyla stigma (Ponerinae), with special reference to mutual antennal rubbing between nestmates (Hymenoptera)

In the ponerine ant species Pachycondyla stigma the social organization and reproductive activity is closely linked with the rate at which individual colony members perform mutual antennal rubbings with nestmates. During these encounters the ants rub their antennae over the openings of a front-tibial gland of the encountered nestmates. The inseminated queen engaged in such mutual rubbings at a much higher rate than non-inseminated queens and workers. The reproductive dominance of the mated queen was further enhanced by extremely aggressive behavior of workers toward other egg-laying queens. Once the mated queen was removed from the colony, mutual antennal rubbings among virgin queens and aggressive behavior increased. We hypothesize that the tibial glands in the front-legs of queens produce either an inhibitory chemical signal, or more likely, the secretion signals the reproductive state to nestmates who might respond by refraining from reproduction.