Mechanisms of dispersed central-place foraging in polydomous colonies of the Argentine ant

Many species of ants occupy multiple nests, a condition known as polydomy. Because of their decentralized structure, polydomous colonies may be remove d from some of the constraints associated with classic central-place foragi ng. We used laboratory and field experiments to assess the mechanisms invol ved in dispersed central-place foraging in polydomous colonies of the Argen tine ant Linepithema humile, a widespread invasive species. Both in the lab oratory and in the field, Argentine ants established new nests at sites loc ated near food. Laboratory colonies of L. humile redistributed workers, bro od and resources among nests in response to the spatial heterogeneity of fo od resources. In addition, laboratory colonies formed recruitment trails be tween nests in the,context of foraging, providing a mechanism for the trans port of material between nests. This highly flexible System of allocating n ests, workers and brood throughout a colony's foraging area potentially inc reases foraging efficiency and competitive ability. The importance of polyd omy as a determinant of competitive;ability is underscored by its prevalenc e among ecologically dominant ants, including most, if not all, highly inva sive species. (C) 2000 The Association for the Study of Animal Behaviour.