Aphid protective symbionts as unseen drivers of population and community dynamics and the impact for biological control

蚜虫是重要的农业害虫，以植物为食，传播毁灭性的植物病毒。生物防治方法被越来越多地用于防治蚜虫，要么将天敌引入农业生态系统，要么对农业生态系统进行管理，以支持更多的天敌。本研究考察了抑蚜菌根菌、拟寄生蜂、昆虫病原真菌和野花条对农作物蚜虫种群的抑制作用。几乎所有蚜虫都寄主一个初级细菌共生体和许多寄主次生细菌共生体。后者可以带来广泛的好处，包括抵抗昆虫病原真菌和拟寄生虫等天敌，但以蚜虫的繁殖产量为代价。因此，蚜虫共生体可以影响蚜虫种群的生长和动态，降低生物防治的效果。大多数蚜虫-共生体研究都是在豌豆蚜虫模型上进行的，但物种特异性的结果意味着这些研究很难推断到其他蚜虫。谷类蚜虫（Sitobion avenae）的研究相对广泛，其寄主的共生体比许多其他已研究的蚜虫种类都多，为研究蚜虫的共生体群落提供了一个有用的系统。本项目将采用对照实验来研究蚜虫共生体如何改变蚜虫种群动态，从而对生物防治产生影响。Objectives1。利用田间采集的蚜虫样品，通过抗生素固化和显微注射对蚜虫体内微生物群进行调控，培育出一套实验性的谷物蚜虫-共生系。2. 在不同的天敌（昆虫病原真菌和拟寄生虫）的挑战下，确定寄主内共生体的成本和收益。为了利用人工群落生态系统和野外实验跟踪种群/群落随时间的动态变化，最近的荟萃分析强调了谷物蚜虫及其细菌共生体的物种特异性信息的缺乏，而最近的野外研究表明，共生群落对田间管理和天敌丰度的强烈响应。我们建立的研究系统使用了广泛的天敌和抑制蚜虫的根瘤菌，有广泛的机会创建人工群落来跟踪蚜虫共生系的种群/群落动态。

BackgroundAphids are important agricultural insect pests that feed on plants and transmit devastating plant viruses. Biological control methods are increasingly being used to combat aphids, either by introducing natural enemies into the agroecosystem or managing the agroecosystem to support higher numbers of natural enemies. Our research investigates effects of aphid-suppressing rhizobacteria, parasitoid wasps, entomopathogenic fungi, and wildflower strips for reducing aphid populations on crop plants.Almost all aphids host a primary bacterial symbiont and many host secondary bacterial symbionts. The latter can confer wide benefits, including resistance to natural enemies as entomopathogenic fungi and parasitoids, but at a cost to aphid reproductive output. Thus, aphid symbionts can impact aphid population growth, dynamics, and reduce the efficacy of biological control. Most aphid-symbiont research has been on the model pea aphid, but species-specific outcomes mean these are difficult to extrapolate to other aphids. The cereal aphid (Sitobion avenae) has been relatively widely studied and tends to host more symbionts than many other studied aphid species, providing a useful system to study aphid symbiont communities. This project will use controlled experiments to investigate how aphid symbionts alter aphid population dynamics with consequences for biological control. Objectives1. To develop a set of experimental cereal aphid-symbiont lines from field collected samples, by manipulating the aphid internal microbiome through antibiotic curing and microinjections. 2. To determine the costs and benefits of hosting endosymbionts when challenged with different natural enemies (entomopathogenic fungi and parasitoids).3. To follow population/community dynamics over time using artificial community mesocosms and field experimentsNovelty and TimelinessA recent meta-analysis highlighted the lack of species-specific information for cereal aphids and their bacterial symbionts, while recent field studies have shown strong responses of symbiont communities to field management and the abundance of natural enemies. Our established research system uses a wide range of natural enemies and aphid-suppressing rhizobacteria, with broad opportunities to create artificial communities to follow the population/community dynamics of aphid-symbiont lines.