The response of foraging Argentine ants, Linepithema humile, to disturbance

Reducing the risk of predation is an important feature of the feeding behav iour of most animals. In social insects, foraging workers are particularly vulnerable, and the ability to trade-off mortality risk against food value may provide a considerable competitive advantage for the colony. We investi gated the response of Argentine ants, Linepithema humile, to different kind s of disturbance while workers foraged on food of differing quality. The be haviour of disturbed individuals was influenced by group size, by the behav iour of nearby nestmates and by how much food had already been consumed. Wh en in large groups, workers were less likely to leave the foraging arena an d resumed feeding more rapidly. This response was even more marked among wo rkers whose gasters were only partially replete. However, individuals took more time to resume feeding and became more likely to run away from a food source when greater numbers of ants were disturbed. These influences may al low foraging groups to maximise food intake while minimising the mortality of workers.