Foraging activity and immunocompetence in workers of the bumble bee,Bombus terrestrisL

Abstract

A fundamental assumption of coevolutionary models of host-parasite relations is that resistance is costly. Costs are envisioned as phenotypic or genetic trade-offs in the allocation of limited resources to specific tasks. Using workers of the bumble bee Bombus terrestris L., we tested experimentally whether foraging effort, an energetically costly and crucially important task that ensures colony growth, survival and reproduction, is costly in terms of reduced resistance against parasite attack. The experiment showed that indeed workers allowed to forage showed lower levels of immunocompetence, as measured by the degree of encapsulation of a novel antigen, than workers prevented from foraging activity.