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。这既是自然界的一个基本过程，也是农业中的一个主要问题，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。除了昆虫本身的能力，这是很好的研究，最近的证据表明，细菌生活在昆虫肠道可以帮助分解植物毒素。这种情况何时以及如何发生，以及它对昆虫对植物损害的总体贡献，人们知之甚少。这项研究的目的是确定哪些细菌可以分解两种常见作物家族（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。了解昆虫使植物毒素失效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，减少对广谱杀虫剂的需求。该项目还将为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，实验室有30名学生。学生将饲养昆虫，用不同的细菌感染它们，测量对昆虫健康和植物消费的影响，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。这项研究的总体目标是预测肠道微生物群为昆虫提供解毒援助的程度，测试宿主植物通才比专家更能从微生物促进中受益的假设。本研究以取食茄科和禾本科植物的甲虫、蝗虫和毛虫为研究对象，将：（1）测定野生昆虫肠道菌群中化感物质降解菌的丰度。研究人员将通过16 S扩增子测序来表征肠道微生物组成，并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测定来测量。(2)测量体内微生物解毒的程度。研究人员将用毒素降解或非降解的分离物对通才和特种昆虫进行分离，并允许昆虫以植物为食。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健康和植物消费的影响。通才昆虫和专业昆虫将在它们的宿主植物上饲养，接种一种能够或不能降解植物主要毒素的分离物。研究人员将比较昆虫的生长速度、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动物中的总体重要性（或缺乏重要性），并对肠道微生物群在植物昆虫化学军备竞赛中的作用展开一项长达职业生涯的调查，这一过程产生了大部分地球陆地生物多样性。该奖项由共生组织、该奖项反映了NSF的法定使命，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.