SPATIAL FIDELITY AND INDIVIDUAL FORAGING SPECIALIZATIONS IN THE NEOTROPICAL PONERINE ANT, ECTATOMMA-RUIDUM ROGER (HYMENOPTERA, FORMICIDAE)

In the Neotropical ponerine ant Ectatomma ruidum, workers involved in outside activities specialize into five behavioral categories which ma y be defined both on the basis of their fidelity to a given foraging s ite and according to their individual specialization in choice of food items or to the behavioral tasks they performed. We distinguished: on one hand hunters, honey-collecting workers and unspecialized intermed iates between these two groups, and on the other hand nest-maintenance workers and patrollers clustered as ''non-foragers''. Moreover, among both hunters and honey-collectors, two different subsets of individua ls can be segregated according to their rate of activity: ''specialist s'' and ''elite-specialists''. Elitism (sensu Oster and Wilson 1978) a nd behavioral specialization are two different phenomena which can be invoked to explain the performances of an individual. In laboratory co nditions, and apart from their specialization in choice of food items, honey-collecting workers show a high spatial fidelity and use visual cues (a cross, a circle or a triangle) to locate the site on which the y specialize. The adaptive value of the cognitive capacities linked to spatial fidelity are discussed according to the natural variability i n local availability of certain food type.