DISSERTATION RESEARCH: Do gut microbiota affect caterpillar herbivory and fitness?

最近的研究表明，包括人类在内的一些动物严重依赖栖息在肠道中的数万亿细菌和其他微生物（“肠道微生物群”）来消化食物和提供营养。尽管这种微生物伙伴关系可能发生在所有动物中，但在大多数动物中仍未被探索。该项目评估了肠道微生物群在毛虫中的作用，其中一些是全球性的破坏性作物害虫，因此具有重大的经济利益。了解毛毛虫是否依赖肠道微生物群来喂养和生长，有助于设计更有效地控制它们的策略。研究人员将使用烟草角虫毛虫进行一项实验，这是番茄和烟草植物的一种常见害虫。这个项目的发现将促进对动物和微生物在多大程度上相互依赖的科学理解。这项研究还将为一名社区大学生提供研究经验，并将通过教育研讨会和博物馆活动吸引公众。研究人员将通过实验验证烟草角虫（Manduca sexta）肠道微生物群影响宿主摄食行为和适应性的假设。该实验将在亚利桑那州东南部进行，那里有大量的野生M. sexta以曼陀罗植物为食。为了控制肠道微生物群，研究人员将使用抗生素在不改变叶片化学或营养特性的情况下，选择性地去除莱特氏菌中的微生物。将测量和比较对照组和抗生素治疗组之间幼虫的摄食率和发育，以及由此产生的成虫的繁殖力。此外，肠道微生物群落的大小和组成将使用DNA测序和荧光显微镜进行表征。先前的DNA测序数据表明，与其他动物相比，m.s sexta肠道中的微生物数量极低。此外，毛毛虫肠道内的极端化学条件表明，在那里检测到的肠道微生物不太可能具有代谢活性。因此，研究人员预计肠道微生物群不会在宿主的喂养或健康中发挥重要作用。这一结果将挑战目前动物生长和繁殖通常严重依赖微生物共生的范式。

Recent studies have shown that some animals, including humans, are heavily dependent on trillions of bacteria and other microorganisms that inhabit their gut ("gut microbiota") to digest food and provide nutrients. Although this microbial partnership likely occurs in all animals, it remains unexplored in most. This project assesses the role of gut microbiota in caterpillars, some of which are globally destructive crop pests and thus of major economic interest. Understanding whether caterpillars are reliant on gut microbiota for feeding and growth could help in designing strategies for controlling them more effectively. Researchers will conduct an experiment using the tobacco hornworm caterpillar, a common pest of tomato and tobacco plants. Findings of this project will advance scientific understanding of how much animals and microbes have evolved to depend on each other. This study will also provide research experience for a community college student and will engage the public through an educational workshop and a museum event.Investigators will experimentally test the hypothesis that gut microbiota in the tobacco hornworm, Manduca sexta, affect host feeding behavior and fitness. The experiment will be based in southeastern Arizona, where a large population of wild M. sexta feed on the plant Datura wright-ii. To manipulate gut microbiota, researchers will use antibiotics to selectively remove microbes from D. wrightii without altering leaf chemical or nutritional properties. Feeding rates and development of the caterpillars, as well as fecundity of the resulting adult moths, will be measured and compared between control and antibiotic-treated groups. In addition, the size and composition of gut microbial communities will be characterized using DNA sequencing and fluorescence microscopy. Previous DNA sequencing data indicate that the number of microbes in the M. sexta gut is extremely low relative to other animals. Further, extreme chemical conditions within the caterpillar gut suggest that the gut microbes detected there are unlikely to be metabolically active. Therefore, the researchers anticipate that gut microbiota will not play a large role in host feeding or fitness. This result would challenge the current paradigm that animal growth and reproduction typically depend heavily upon microbial symbiosis.