Let the most motivated win: resource value components affect contest outcome in a parasitoid wasp

Studying physical contests for indivisible resources is a major theme in behavioral ecology. Intensity (aggressiveness) and outcome of such contests may be influenced by individual abilities to gain and keep the resource (Resource Holding Potential, RHP), but also by the value they place in the resource (Resource Value, RV). Contestants can assess resource quality directly (objective RV) or estimate it according to their physiological status and their experience (subjective RV). In some parasitoid species, adult females fight for hosts on which they lay eggs and feed. Here, we studied contests between two females of the solitary parasitoid Eupelmus vuilleti when exploiting simultaneously a host: a fourth instar larva or a pupa of the cowpea seed beetle Callosobruchus maculatus. We first demonstrated that fourth instar larvae represent a resource of higher objective RV because offspring that developed on such hosts were heavier. We then showed that both objective (host quality) and subje...