Biogenic amines and individual olfactory learning in the ants Camponotus fellah.

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

Toulouse, Francia

Congreso; Colloque de la section française de l´ UIEIS (Union Internationale pour l Etude des Insectes Sociaux); 2007

The individual olfactory learning abilities of ants of the genus Camponotus were recently characterized under controlled laboratory conditions by using a Y-maze. Ants learnt to discriminate between two pure odorants simultaneously presented (differential conditionning), one rewarded with sucrose solution and the other punished with quinine solution. Associative learning and memory in insects are modulated by biogenic amines which may act as substitutes for appetitive or aversive reinforcements. These amines depress or facilitate a wide range of insect behaviours but nothing is known about their possible modulatory role in olfactory learning and memory in ants. We focused on the effect of octopamine and dopamine, two important biogenic amines for learning in insects, on the olfactory acquisition and memory in C. fellah ants. Dopamine (DA) and octopamine (OA) were orally administrated in the sucrose solution fed to independent groups of ants. Preliminary results showed that DA-treated ants learned faster the association than OA-treated and control ones, whereas no difference between groups was found at the end of the conditioning. Further experiments used ants treated with DA, 67-ADTN (an agonist of the honeybees dopaminergic receptors), OA or tyramine (TA, precursor of octopamine), and control ants. Following the olfactory conditioning, we performed discriminative tests to determine if ants learnt the association between the odour and the sucrose reward (appetitive learning) and/or the association between the odour and the punishment with quinine solution (aversive learning). We found that the appetitive association is learnt by all the groups whereas the aversive one did not. We confirmed the facilitatory action of dopamine on olfactory learning in ants, and to a lesser extent with its agonist 67-ADTN. Supplementary studies showed however that treatment with DA decreased the sucrose responsivness, which can not explain that DA increased learning performances with sugar reward.