Antennal asymmetry is not associated with social behaviour in Australian Hymenoptera

Abstract

AbstractLateralisation of biological form and function are well known for vertebrates and are being increasingly documented among invertebrates in recent years. Behavioural lateralisation in insects, together with asymmetrical distributions of antennal sensilla, has been linked to the communication challenges faced by social, but not solitary, insects. Recent evidence on patterns of asymmetry in insects outside of the Hymenoptera suggests that this explanation for antennal sensilla asymmetry may not be phylogenetically constrained. We explore this possibility by examining the distribution of antennal sensilla in three species of ants (Formicidae), the meat ant Iridomyrmex purpureus (Dolichoderinae), the green tree ant Oecophylla smaragdina (Formicinae) and the shield ant Meranoplus sp. (Myrmicinae) in which colony organisation is eusocial, and two species of nomiine bees, Mellitidia tomentifera and Reepenia bituberculata (Halictidae: Nomiinae), where colony organisation is not eusocial. Our results demonstrate that while there are differences in the left–right asymmetry of antennal sensilla basiconica in workers of the formicine ant I. purpureus, there is no consistent sensilla asymmetry across the five species. We find a negative correlation between antennal sensilla density and body size in R. bituberculata, which was not apparent in the other species. Our results contradict the suggestion that asymmetrical distribution of antennal sensilla is associated with the evolution of eusocial behaviour.