Nest-mate recognition and the effect of distance from the nest on the aggressive behaviour of Camponotus chilensis (Hymenoptera : Formicidae)

Abstract

Nest-mate recognition and territorial behaviour in ants are widely studied phenomena. However, few studies have analysed, under field conditions, how nest-mate recognition varies with distance from the resident's colony. In a natural population of Camponotus chilensis in central Chile, we studied nest-mate recognition and spatial variation in aggressive behaviour. C. chilensis individuals were able to discriminate nest-mates from intruders, showing no aggression toward nest companions, while aggressiveness toward allo-colonial con-specifies decreased significantly with distance. Further, the overall number of interactions and the agaressiveness of the resident ants were significantly greater at 25 cm from their colony than at further distances. Given that antennation behaviour is regularly present at all distances from the nest. it seems to entail information acquisition. Biting and intruder-dragging, the most conspicuous aggressive displays, were mainly observed at distances close to the resident colony. Other behaviours such as threatening with open mandibles, ventral bending of the,gaster, and backward-movement, were observed at all distances, and they seem to represent the first signs of intruder rejection.