Trophallaxis mediates uniformity of colony odor in Cataglyphis iberica ants (Hymenoptera, Formicidae)

We studied the effect of nestmate separation on trophallaxis in the polydom ous ant Cataglyphis iberica. After dividing three colonies into two equival ent subgroups, one queenright and one queenless, we quantified the frequenc y of trophallaxis within each subgroup, between the workers from the two su bgroups ("mixed" trophallaxis), and trophallaxis involving the queen. Obser vations of trophallaxis were conducted over four periods of time: for 2 wee ks before the separation of the two subgroups, 8 weeks during separation, i mmediately after reunification, and 3 weeks following reunification. Subgro ups were identically fed on the eve of each day of observation. Group separ ation induced an increase in "mixed" frequencies of trophallaxis just after reunification, after which trophallaxis returned to the initial level obse rved before separation. Previous results showed that group separation in C. iberica induces hydrocarbon profile divergence and that reunification rest ores this chemical modification. The current results seem to indicate that increased trophallaxis permits a uniform odor to be reestablished among pre viously separated ants. Trophallaxis involving the queen is infrequent and does not seem to be crucial in the process of odor exchange. Our data confi rm that trophallaxis plays a key role in establishing the "Gestalt" colony odor, particularly among naturally separated satellite nests in a polydomou s species like C. iberica.