Unrewarding experience with a novel environment modulates olfactory response in the host-searching behavior of parasitic wasps

Generalist insects, which utilize various food resources from various environments, must make decisions to locate resources using novel environmental sensory stimuli when they arrive in a new habitat. In addition to the innate response repertoire, such decision using novel stimuli can include an experience-based process. Here, we showed that the generalist parasitic wasp Aphidius gifuensis altered its olfactory responses after exposure to nonnatal habitat environments, i.e., host plants of aphids. In our laboratory experiments, overnight exposure of female wasps to nonnatal broad bean plants reduced their olfactory preference for uninfested bean plants and induced an olfactory preference for host-infested plants over uninfested plants of both broad bean and wheat. The decrease in olfactory preference for uninfested plants was not observed in wasps with overnight exposure to their natal wheat plants. In addition, the olfactory preference for uninfested wheat plants over uninfested bean plants was not observed without previous rewarding experience (oviposition) on the natal wheat plants prior to the overnight exposure to uninfested bean plants. These results suggest that a certain period of unrewarding experience (residency without host finding) on nonnatal plants promoted emigration from the unrewarded environment and increased the wasp’s response to olfactory cues from host-infested plants of both species. This study shows negative experience with uninfested plants plays a key role in host-searching behavior and habitat (host plant) selection in the wasp.