Abstract: Leaf-cutting ants live in symbiosis with a basidiomycete fungus that is exploited as a source of nutrients for ant larvae. Tests of brood transport revealed that Acromyrmex laticeps nigrosetosus workers did not discriminate a concolonial brood from an alien brood. The same result was observed with tests of fungus transport. Adult workers showed no aggressive behaviour to workers from other alien colonies (non-nestmates). There was no qualitative variation in the chemical profiles of larvae, pupae and adult workers from the different colonies. However, quantitative differences were observed between the different colonies. Hypotheses about the lack of intraspecific aggression in this subspecies of ants are discussed.

Abstract: Bioassays were conducted in both laboratory and the field to determine if monogynous colonies of Acromyrmex subterraneus molestans (Myrmicinae, Attini) adopt queens from other colonies of the same subspecies. The results suggest that the adoption of fertilized queens is a possible mechanism to explain the occurrence of colonies with multiple queens in this subspecies. Only minor workers were able to discriminate queens from other colonies and were aggressive toward them. Therefore, queen recognition differs among subcastes.