NEST SEPARATION AND THE DYNAMICS OF THE GESTALT ODOR IN THE POLYDOMOUS ANT CATAGLYPHIS-IBERICA (HYMENOPTERA, FORMICIDAE)

In the polydomous ant species Cataglyphis iberica, nests belonging to the same colony are completely separated during hibernation. In order to examine whether this separation induces changes both in the hydroca rbon profile and in recognition ability between adult nestmates, we se parated groups of workers for several months under two different condi tions: at hibernation temperature and at room temperature. At room tem perature, recognition remained unchanged but separation led to longer mutual antennations relative to non-separated controls. When half of a colony was placed under hibernation conditions, antennal interactions also increased in duration and a few aggressive interactions emerged between separated ants. This aggressiveness never reached the intercol onial level observed in this species. In both cases, the hydrocarbon p rofiles showed differences between individuals after separation while remaining homogeneous within each nest. This chemical modification may induce the longer antennations observed. After separated groups were reunited, individuals recovered their previous antennation pattern and a convergence in hydrocarbon profiles was again observed. These concu rrent observations suggest that hydrocarbons are transferred between n estmates. In C. iberica, the formation of the colonial odor seems to f ollow the ''Gestalt'' model which allows all satellite nests of a colo ny to have a common colonial odor. In the field, temporary nest isolat ion during hibernation may induce divergence between satellites. The r ole of adult transport in connecting nests during the active season to obtain an efficient Gestalt odor is discussed.