CAREER: Prevalence, magnitude, and importance of gut microbial detoxification services in insect herbivory

该奖项全部或部分由《2021年美国救援计划法案》（公法117-2）资助。昆虫吃植物。这既是自然界的一个基本过程，也是农业的一个主要问题，导致作物损失和昂贵的农药处理。植物通过产生对昆虫有毒的天然化学物质来保护自己，但昆虫有很多方法来克服这些毒素。除了昆虫自身的能力之外，最近的证据表明，生活在昆虫肠道中的细菌可以帮助分解植物毒素。这种情况何时、如何发生，以及昆虫对植物损害的总体影响，人们知之甚少。这项研究的目的是确定哪些细菌能分解来自两种常见作物家族（番茄家族和卷心菜家族）的毒素，并测量这些细菌在多大程度上帮助昆虫吃掉这些植物。了解昆虫破坏植物毒素的不同方式将有助于我们设计更有效、更有针对性的昆虫控制策略。最终，这可以减少作物损失，减少对广谱农药的需求。该项目还将为一所西班牙裔服务机构的本科生提供实践研究经验，课堂上共有120名学生，实验室里有30名学生。学生们将饲养昆虫，用不同的细菌感染它们，测量昆虫健康和植物消耗的影响，并在公共和科学场所展示他们的结果。这将培养我们社会的未来成员和下一代STEM研究人员的科学思维。本研究的首要目标是预测昆虫肠道微生物群提供的解毒援助的大小，测试宿主植物通才比专家从微生物促进中获益更多的假设。利用以茄科和十字花科植物为食的甲虫、蚱蜢和毛虫，本研究将：(1)确定野生昆虫肠道微生物群中化感化学降解细菌的丰度。研究人员将通过16S扩增子测序来表征肠道微生物组成，同时从同一昆虫个体中分离出活的肠道细菌。这些细菌降解化感物质的能力将通过基于培养的分析来测量。(2)测定体内微生物解毒的程度。研究人员将给通才昆虫和专才昆虫接种能降解毒素或不降解毒素的分离物，并让这些昆虫以植物为食。将测量昆虫粪便中排泄的化感物质的浓度，以确定发生了多少微生物降解。(3)量化肠道微生物促进作用对昆虫适合度和植物消耗的影响。通用型和专门型昆虫将在它们的寄主植物上饲养，接种一种分离物，这种分离物可以或不可以降解植物的一种主要毒素。研究人员将比较这些昆虫的生长速度、发育到成年的时间、存活率和消耗的总叶面积。这项工作将量化肠道微生物群在昆虫食草性中的总体重要性（或缺乏重要性），并启动一项长达职业生涯的研究，研究肠道微生物群在植物-昆虫化学军备竞赛中的作用，这一过程产生了地球上大部分的陆地生物多样性。该奖项由综合有机体系统部门的共生、感染和免疫项目以及环境生物学部门的人口和社区生态项目共同资助。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).Insects eat plants. This is both a basic process in nature and a major problem in agriculture, resulting in crop losses and costly pesticide treatments. Plants defend themselves by producing natural chemicals that are toxic to insects, but insects have many ways to overcome these toxins. In addition to insects’ own abilities, which are well studied, recent evidence suggests that bacteria living in the insect gut can help to break down plant toxins. When and how this happens, and its overall contribution to plant damage by insects, are poorly understood. The goal of this research is to identify which bacteria break down toxins from two common crop families (the tomato family and the cabbage family) and measure how much these bacteria help insects eat these plants. Understanding the different ways insects disable plant toxins will help us design more effective, targeted insect control strategies. Ultimately this could reduce crop losses and lessen the need for broad-spectrum pesticides. This project will also provide hands-on research experience for undergraduates at a Hispanic-serving institution, reaching a total of 120 students in the classroom and 30 students in the laboratory. Students will rear insects, infect them with different bacteria, measure the effects on the insects’ health and plant consumption, and present their results in public and scientific venues. This will train both future members of our society and the next generation of STEM researchers in scientific thinking.The overarching goal of this research is to predict the magnitude of detoxification assistance provided to insects by their gut microbiota, testing the hypothesis that host plant generalists will benefit more from microbial facilitation than specialists. Using beetles, grasshoppers and caterpillars feeding on Solanaceous and Brassicaceous plants, this research will: (1) Determine the abundance of allelochemical-degrading bacteria within wild insects’ gut microbiota. Researchers will characterize gut microbial composition via 16S amplicon sequencing and simultaneously isolate live gut bacteria from the same insect individuals. The ability of these bacteria to degrade allelochemicals will be measured via culture-based assays. (2) Measure the magnitude of microbial detoxification in vivo. Researchers will inoculate generalist and specialist insects with toxin-degrading or non-degrading isolates and allow the insects to feed on plants. Concentrations of allelochemicals excreted in insect frass will be measured to determine how much microbial degradation occurred. (3) Quantify the impact of gut microbial facilitation on insect fitness and plant consumption. Generalist and specialist insects will be reared on their host plants, inoculated with an isolate that does or does not degrade one of the plant’s major toxins. Researchers will compare the insects’ growth rate, development time to adulthood, survival, and total leaf area consumed. This work will quantify the overall importance – or lack thereof – of gut microbiota in insect herbivory and launch a career-long investigation of the role of gut microbiota in the plant-insect chemical arms race, a process that has generated much of Earth’s terrestrial biodiversity.This award was jointly funded by the Symbiosis, Infection and Immunity Program in the Division of Integrative Organismal Systems and by the Population and Community Ecology Program in the Division of Environmental Biology.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.