Do past experience and competitive ability influence foraging strategies of parasitoids under interspecific competition?

Abstract

Abstract1. In solitary parasitoids, several species can exploit the same host patch and competition could potentially be a strong selective agent as only one individual can emerge from a host. In cereal crops,Aphidius rhopalosiphiandA. ervishare the grain aphidSitobion avenaeas host.2. The present work studied foraging strategies of both species on patches already exploited by the other species. The study analysed larval competition in multi‐parasitised hosts and compared the foraging behaviour of females with and without previous experience.3. It was found thatA. erviwins larval competition three times more often thanA. rhopalosiphi. Both species spent less time on patches exploited by a heterospecific than on unexploited ones. When they foraged on heterospecifically exploited patches, experienced females induced less mortality in aphids than inexperienced ones.4. AlthoughA. rhopalosiphiis a specialist on cereal aphids and is the most abundant species due to its early appearance in the season,S. avenaeis still a profitable host forA. ervi, because: (i)A. rhopalosiphileaves patches partially exploited, (ii)A. erviwins larval competition in three out of four multi‐parasitised hosts, and (iii)A. erviis only slightly deterred by the cornicular secretions of the host and can thus easily parasitise hosts.