Division of Evolution, Infection and Genomics, School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Manchester, M13 9PT, UK.
Departamento de Ingeniería, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru.
BMC Ecol Evol. 2022 Mar 19;22(1):33. doi: 10.1186/s12862-022-01991-1.
Host-parasite interactions represent complex co-evolving systems in which genetic and associated phenotypic variation within a species can significantly affect selective pressures on traits, such as host immunity, in the other. While often modelled as a two-species interaction between host and parasite, some systems are more complex due to effects of host enemies, intraguild predation, and endosymbionts, all of which affect host immunity. However, it remains unclear how these factors, combined with genetic variation in the host and the parasitoid, affect host immunity. We address this question in an important agricultural pest system, the pea aphid Acyrthosiphon pisum, which shows significant intraspecific variability in immunity to the parasitoid wasp Aphidius ervi. In a complex experiment, we use a quantitative genetic design in the parasitoid, two ecologically different aphid lineages and the aphid lion Chrysoperla carnea as an intraguild predator to unravel the complex interdependencies.
We demonstrate that aphid immunity as a key trait of this complex host-parasite system is affected by intraspecific genetic variation in the parasitoid and the aphid, the interaction of intraspecific genetic variation with intraguild predation, and differences in defensive endosymbionts between aphid lineages. Further, aphid lineages differ in their altruistic behaviour whereby infested aphids move away from the clonal colony to facilitate predation.
Our findings provide new insights into the influence of endosymbiosis and genetic variability in an important host-parasitoid system which is influenced by natural enemies of the parasitoid and the aphid, including its endosymbiont communities. We show that endosymbiosis can mediate or influence the evolutionary arms race between aphids and their natural enemies. The outcome of these complex interactions between species has significant implications for understanding the evolution of multitrophic systems, including eco-agricultural settings.
宿主-寄生虫相互作用代表着复杂的共同进化系统，其中一个物种内的遗传和相关表型变异可以显著影响另一个物种的特征选择压力，例如宿主免疫。虽然通常将宿主和寄生虫之间的相互作用建模为两种物种之间的相互作用，但由于宿主天敌、内共生体和内寄生的影响，一些系统更为复杂，所有这些都会影响宿主免疫。然而，这些因素与宿主和寄生蜂的遗传变异相结合如何影响宿主免疫仍不清楚。我们在豌豆蚜 Acyrthosiphon pisum 这一重要农业害虫系统中解决了这个问题，该系统在对寄生蜂蚜茧蜂 Aphidius ervi 的免疫力方面表现出显著的种内变异性。在一个复杂的实验中，我们在寄生蜂、两个生态不同的蚜虫谱系和蚜虫天敌草蛉 Chrysoperla carnea 中使用数量遗传设计来揭示复杂的相互依存关系。
我们证明，作为这个复杂的宿主-寄生虫系统的关键特征的蚜虫免疫力受到寄生蜂和蚜虫的种内遗传变异、种内遗传变异与内寄生相互作用以及蚜虫谱系之间防御性共生体的差异的影响。此外，蚜虫谱系在其利他行为上存在差异，即受感染的蚜虫会远离克隆群体以促进捕食。
我们的研究结果为共生体和遗传变异性在一个重要的宿主-寄生系统中的影响提供了新的见解，该系统受到寄生蜂和蚜虫的天敌的影响，包括它们的共生体群落。我们表明，共生体可以调节或影响蚜虫及其天敌之间的进化军备竞赛。这些物种之间复杂相互作用的结果对理解多营养层系统的进化具有重要意义，包括生态农业环境。
