Department of Plant Protection, Faculty of Agriculture and Natural Resources, University of Tehran, Karaj, Iran.
Department of Biology, Lund University, Lund, Sweden.
Naturwissenschaften. 2021 Mar 24;108(2):13. doi: 10.1007/s00114-021-01727-z.
Host preference behavior can result in adaptive advantages with important consequences for the fitness of individuals. 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 their own 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. Here, we investigated the effect of infection with the facultative bacterial symbiont Wolbachia on post-eclosion host preference in the parasitoid wasp Trichogramma brassicae (Hymenoptera: Trichogrammatidae). We compared host preference in Wolbachia-infected individuals and uninfected adult female parasitoids after rearing them on two different Lepidopteran hosts, namely the flour moth Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) or the grain moth Sitotroga cerealella (Lepidoptera: Gelechiidae) in choice and no choice experimental design (n = 120 wasps per each choice/no choice experiments). We showed that in T. brassicae, Wolbachia affects the post-eclosion host preference of female wasps. Wolbachia-infected wasps did not show any host preference and more frequently switched hosts in the laboratory, while uninfected wasps significantly preferred to lay eggs on the host species they developed on. Additionally, Wolbachia significantly improved the emergence rate of infected wasps when reared on new hosts. Altogether, our results revealed that the wasp's infection with Wolbachia may lead to impairment of post-eclosion host preference and facilitates growing up on different host species. The impairment of host preference by Wolbachia may allow T. brassicae to shift between hosts, a behavior that might have important evolutionary consequences for the wasp and its symbiont.
宿主偏好行为可能会带来适应优势，对个体的适应度产生重要影响。Hopkin 的宿主选择原则（HHSP）表明，营养层次较高的生物会优先选择其幼虫阶段所发育的宿主物种。尽管该原则在许多草食性和捕食性昆虫中得到了广泛研究，但据我们所知，它从未在寄生性昆虫携带自私内共生乘客的情况下进行过测试。在这里，我们研究了兼性细菌共生体 Wolbachia 对寄生蜂赤眼蜂（膜翅目：赤眼蜂科）出蜂后宿主偏好的影响。我们比较了在两种不同鳞翅目宿主（粉斑螟 Ephestia kuehniella Zeller 和玉米螟 Sitotroga cerealella）上饲养的 Wolbachia 感染个体和未感染的成年雌性寄生蜂在出蜂后的宿主偏好，使用选择和无选择实验设计（每个选择/无选择实验有 120 只蜂）。我们发现，在赤眼蜂中，Wolbachia 影响雌性蜂的出蜂后宿主偏好。感染 Wolbachia 的蜂没有表现出任何宿主偏好，并且在实验室中更频繁地更换宿主，而未感染的蜂则显著倾向于在其发育的宿主物种上产卵。此外，当在新宿主上饲养时，Wolbachia 显著提高了感染蜂的出蜂率。总的来说，我们的结果表明，蜂的 Wolbachia 感染可能导致出蜂后宿主偏好受损，并促进在不同宿主物种上生长。Wolbachia 对宿主偏好的损害可能使赤眼蜂能够在宿主之间转换，这种行为可能对蜂及其共生体具有重要的进化后果。
