Wolbachiamanipulates host pre-imaginal learning in a parasitoid wasp

Abstract

AbstractThe Hopkin’s host-selection principle (HHSP) suggests that organisms at higher trophic levels demonstrate a preference for the host species on which they developed during larval stage. Although investigated in many herbivorous and predatory insects, the HHSP has, to our knowledge, never been tested in the context of insects hosting selfish endosymbiotic passengers such as the maternally inherited bacteriumWolbachia pipientis. Here, we investigate the effect ofWolbachiainfection on host pre-imaginal learning in the parasitoid waspTrichogramma brassicae(Hymenoptera: Trichogrammatidae). We compare host-choice inWolbachia-infected and uninfected adult female parasitoids after rearing them on two different Lepidopteran hosts, namely the flour mothEphestia kuehniellaZeller (Lepidoptera: Pyralidae) or the grain mothSitotroga cerealella(Lep.: Gelechiidae). We show that inT. brassicae, Wolbachiaaffect the pre-imaginal learning ability of female wasps.Wolbachiainfected wasps do not show any host preference and easily switch hosts in the laboratory, while uninfected wasps significantly prefer to lay eggs on the host species they developed on. We discuss how the facilitation of a generalist strategy byWolbachiamay allowT. brassicaeto escape intraspecific competition with their uninfected counterparts, and may have important evolutionary consequences for the host and its symbionts.