Long-term olfactory memory in Camponotus ants

ESCHBACH, C.; DUPUY, F.; JOSENS, R; GIURFA, M.

Avignon, Francia

Congreso; Colloque annuel de la Union internationale pour l´étude des insectes sociaux- Section Française; 2006

International Union for the Study of Social Insects (IUSSI) sec. Francesa

Ants of the genus Camponotus rely on olfactory cues to orient in their environment. Recently, we showed that two Camponotus species, fellah and mus, are capable of individual olfactory learning under controlled laboratory conditions. An operant conditioning paradigm allowed us to study their olfactory learning and memory in a Y-maze, in which they had to discriminate between two pure odorants, one rewarded with sucrose solution and the other punished with quinine solution. Ants learned the discrimination after 16 trials but no assays were performed to estimate memory duration and robustness. Here we used Camponotus fellah and addressed the problem of long-term olfactory retention after conditioning. We trained ants with limonene and octanal, two odorants that are well learned and discriminated, and tested them after conditioning with these odours presented without reinforcements. Tests were performed at 24h or 72h post acquisition. In both tests, ants chose significantly the previously rewarded odour and spent more time in the arm of the Y-maze presenting this odour. No extinction of these performances was visible, even after five non-reinforced retention tests. These results show that olfactory long-term memories are established in the C. fellah brain and that these memories are extremely stable and robust.