Leaf-cutter ant species (Hymenoptera: Atta) differ in the types of cues used to differentiate between self and others

Nestmate recognition among most social insects is thought to be mediated by cuticular hydrocarbons. We found that among two closely related ant species, the chemical cues used for recognition vary between them and that they are not cuticular hydrocarbons. Experiments with free-living colonies of Atta laevigata and Atta cephalotes using live and dead dummies, some impregnated with glandular extracts, allowed us to reconstruct the cues by which A. laevigata differentiates itself from A. cephalotes workers. The results suggest that the same odour cues (chemicals from the alarm pheromones and from abdominal exocrine secretions) are used for both inter- and intraspecific recognition systems, achieving discrimination of self (i.e. a nestmate) from others, and that both species differ in the chemical nature of the odour cues used for recognition. Our results suggest that recognition mechanisms vary among ants, and may thus vary among other social insects, and are shaped by various evolutionary forces in addition to kin selection.