Defense by exploitation in the Florida carpenter ant, Camponotus floridanus, at an extrafloral nectar resource

摘要

When resources in a territory have a patchy distribution, intruders may successfully exploit unguarded patches. In such cases, territory owners may use exploitative strategies to reduce the gains of the intruders. The territorial ant Camponotus floridanus attends the leaf nectaries of Urena Lobata, which are also visited by the ant Pseudomyrex mexicanus and other intruders. Residents visited the nectaries at a high rate and in a systematic way, and thereby depressed the mean standing crop per nectary. This reduces the gains of randomly visting intruders which obtain the mean standing crop per nectary visit. Two or three residents were present on large plants and kept the mean standing crop at the same low level as at small plants with a single ant. This is an ideal free distribution of the ants. The resident ants visited the nectaries at a rate which increased in proportion to the nectar production per nectary. This is the expected systematic visitation when nectar production varies between nectares. It is suggested that systematic visitation and maximization of the visitation rate are evolutionarity stable strategies in both residents and intruders. However, the intruders are constrained by the residents, so that they visit the nectaries less frequently and in a random manner, and thus have a lower gain rate. When the resident was temporarily absent, the intruders visited the nectaries at a high rate and systematically.