Vorburger Christoph
Department of Aquatic Ecology, Eawag, 8600 Dübendorf, Switzerland; email:
Institute of Integrative Biology, ETH Zürich, 8092 Zürich, Switzerland.
Annu Rev Entomol. 2022 Jan 7;67:329-346. doi: 10.1146/annurev-ento-072621-062042. Epub 2021 Oct 6.
Insect host-parasitoid interactions abound in nature and are characterized by a high degree of host specialization. In addition to their behavioral and immune defenses, many host species rely on heritable bacterial endosymbionts for defense against parasitoids. Studies on aphids and flies show that resistance conferred by symbionts can be very strong and highly specific, possibly as a result of variation in symbiont-produced toxins. I argue that defensive symbionts are therefore an important source of diversifying selection, promoting the evolution of host specialization by parasitoids. This is likely to affect the structure of host-parasitoid food webs. I consider potential changes in terms of food web complexity, although the nature of these effects will also be influenced by whether maternally transmitted symbionts have some capacity for lateral transfer. This is discussed in the light of available evidence for horizontal transmission routes. Finally, I propose that defensive mutualisms other than microbial endosymbionts may also exert diversifying selection on insect parasitoids.
昆虫宿主与寄生蜂之间的相互作用在自然界中很常见，其特点是宿主具有高度的专一性。除了行为和免疫防御外，许多宿主物种还依靠可遗传的细菌内共生体来抵御寄生蜂。对蚜虫和苍蝇的研究表明，共生体赋予的抗性可能非常强且具有高度特异性，这可能是共生体产生的毒素发生变异的结果。我认为，防御性共生体因此是多样化选择的一个重要来源，通过促进寄生蜂宿主专一性的进化来影响宿主 - 寄生蜂食物网的结构。尽管这些影响的性质也将受到母系传播的共生体是否具有某种横向转移能力的影响，但我考虑了食物网复杂性方面的潜在变化。这将根据水平传播途径的现有证据进行讨论。最后，我提出除了微生物内共生体之外的防御性共生关系也可能对昆虫寄生蜂施加多样化选择。
