Novel approaches to detecting ecological interactions involving beneficial invertebrates

食蚜蝇是农业景观中的益虫：它们是开花植物（包括农作物）的重要传粉者，其幼虫是植物害虫的天敌。食蚜蝇也是鸟类、蜘蛛和黄蜂等捕食者的重要猎物，这些捕食者本身也是有益的物种。此外，食蚜蝇表现出对蜜蜂和黄蜂的视觉模仿，这可能是因为它能欺骗捕食者，让他们认为无害的猎物得到了保护。因此，捕食者-猎物的相互作用可能影响食蚜蝇授粉和害虫控制的有效性，以及模仿的适应性进化。不幸的是，人们对这些相互作用知之甚少：我们不知道哪些物种是食蚜蝇的重要捕食者，也不知道食蚜蝇是否构成了其他有益物种的大部分食物。这个项目将结合遗传学和免疫学来量化食蚜蝇、它们的捕食者和猎物之间的相互作用。基因技术为通过饮食分析来量化捕食者与猎物之间的相互作用提供了新的机会。我们将筛选食蚜蝇捕食的证据，描述食蚜蝇在与耕地相关的食物网中的位置，测试作物害虫天敌之间的拮抗相互作用，并评估农业和林地栖息地鸟类饮食中与作物相关的猎物的重要性。在诺丁汉郡和北威尔士，鸟类粪便将从a)靠近耕地和b)远离耕地的林地收集。黄蜂、食蚜蝇幼虫和蜘蛛将通过扫荡网、手工搜索和诱捕在农田边缘和农作物上收集，在有或没有野花边缘的农场，作为农业环境计划的一部分。该学生将使用食蚜蝇和农作物害虫特异性PCR/qPCR检测来分析来自一系列捕食者的粪便/肠道中食蚜蝇和害虫DNA的发生率/数量，包括鸟类、群居黄蜂（Vespula spp.）和蜘蛛。捕食者肠道内容物的元条形码将用于进一步表征食蚜蝇在捕食者饮食中的贡献。之前用于食虫节肢动物饮食分析的短COI引物将基于已知的猎物类群（食蚜蝇、黄蜂、蜜蜂、农作物害虫）在计算机上进行验证，并使用Illumina内部MiSeq和定制文库制备协议进行测序。除了饮食分析外，学生还将使用抗igy， IgA和IgM免疫分析方法筛选野生鸟类的血液样本，以检测对刺痛膜翅目昆虫毒液的抗体。这些试验将利用完整的毒液制剂和纯化的毒液成分。被黄蜂、蜜蜂或大黄蜂蜇伤的鸟类会产生抗体，这种抗体可以在几个月内被检测到。抗体的证据将为鸟类和有益昆虫之间的生态相互作用提供指示，也将使我们能够评估鸟类避免模仿食蚜蝇的假设，因为它们与膜翅目“模型”的相互作用代价高昂。学生可以选择通过行为实验进一步探索这一假设，测试具有已知抗体谱的鸟类对模拟和非模拟食蚜蝇3D模型的反应。总的来说，我们的目标是深入了解食蚜蝇、其他有益的无脊椎动物和鸟类捕食者之间生态和进化联系的重要性。这些结果将帮助我们了解害虫生物控制的可能影响，以及农业环境计划在促进农业生物多样性方面的价值。

Hoverflies are beneficial insects in agricultural landscapes: they are important pollinators of flowering plants, including crops, whilst their larvae are natural enemies of plant pests. Hoverflies are also important prey for predators, such as birds, spiders and wasps, which are themselves beneficial species. Additionally, hoverflies display visual mimicry of bees and wasps, which probably evolved because it fools predators into thinking that harmless prey are defended. Hence, predator-prey interactions probably influence hoverfly effectiveness in pollination and pest control, and the adaptive evolution of mimicry. Unfortunately, these interactions are poorly understood: we don't know which species are important predators of hoverflies, or whether hoverflies form a large part of the diet of other beneficial species. This project will combine genetics and immunology to quantify interactions between hoverflies, their predators and prey.Genetic techniques provide new opportunities to quantify predator-prey interactions via diet analysis. We will screen predators for evidence of hoverfly consumption, and characterise the position of hoverflies in food-webs associated with arable fields, testing for antagonistic interactions between natural enemies of crop pests, and assessing the importance of crop-associated prey in bird diets in agricultural and woodland habitats. Bird faeces will be collected from woodland a) adjacent to and b) distant from arable fields in Nottinghamshire and North Wales. Wasps, hoverfly larvae and spiders will be collected by sweep-netting, hand-searching and trapping in field margins and crops, on farms with and without wildflower margins deployed as part of agri-environment schemes. The student will use hoverfly- and crop-pest-specific PCR/qPCR assays to analyse the occurrence/quantity of hoverfly and pest DNA in faeces/guts from a range of predators, including birds, social wasps (Vespula spp.) and spiders. Metabarcoding of predator gut contents will be used to further characterise the contribution of hoverflies in predator diets. Short COI primers, previously used in diet analysis of insectivorous arthropods, will be validated in silico based on known prey taxa (hoverflies, wasps, bees, crop pests) and sequenced using in-house Illumina MiSeq and custom library preparation protocols. In addition to diet analysis, the student will screen blood samples from wild birds for antibodies to the venom of stinging Hymenoptera using anti -IgY, IgA and IgM immunoassays. These assays will utilize both complete venom preparations and purified venom components. Birds which have been stung by wasps, honeybees or bumblebees develop antibodies that can be detected for many months. Evidence of antibodies will provide an indication of ecological interactions between birds and beneficial insects, and will also allow us to evaluate the hypothesis that birds avoid mimetic hoverflies because of costly interactions with hymenopteran "models". The student may choose to explore this hypothesis further with behavioural experiments testing the responses of birds with known antibody profiles to 3D models of mimetic and non-mimetic hoverflies.Overall, we aim to provide insights into the importance of ecological and evolutionary links between hoverflies, other beneficial invertebrates, and avian predators. The results will help us understand the likely impact of biological control of pest insects, and the value of agri-environment schemes in boosting farm biodiversity.