Effects of social isolation on hydrocarbon pattern and nestmate recognition in the ant Aphaenogaster senilis (Hymenoptera, Formicidae)

In the non-trophallacting ant Aphaenogaster senilis, a change over time was observed in cuticular and postpharyngeal gland hydrocarbon profiles. A change was also observed after individual social isolation. Short periods of isolation induced amicable reaction, such as allogrooming, which may have facilitated re-integration of the isolated ants into their mother colonies. Longer periods of isolation, on the other hand, caused overt aggression towards the isolated ants when reintroduced into their mother colonies, and also resulted in higher changes in cuticular hydrocarbon profile. This correlation suggests a link between these two phenomena. We suggest that in A. senilis, in the absence of cue transfer by trophallaxis: a) colony odour constitutes a gestalt, and b) the major means of cue transfer is allogrooming. The possible evolution of allogrooming and trophallaxis as cue transfer modalities is discussed.