Community-level effects of defensive endosymbionts

地球上的大多数昆虫物种都携带着特定的细菌，这些细菌是从受感染的雌性昆虫传给后代的。这些细菌中的许多对宿主有益，例如赋予其对病原体的抵抗力。由于昆虫是更大生态群落的重要成员，它们携带的细菌可能会影响这些群落的结构和动态。这项拟议的研究将检查感染特定食用菌苍蝇的特定细菌的几个社区层面的影响。生活在果蝇体内的细菌对寄生线虫的杀菌作用具有抵抗力，从而增加了寄生果蝇的适应能力。此外，细菌极大地影响了这些寄生线虫的种群动态：线虫寄生在缺乏细菌的苍蝇种群中迅速增加，但在受细菌感染的种群中线虫很快就会灭绝。这个项目将研究三个问题：1)细菌如何影响不同种类的竞争苍蝇的相对丰度，无论有没有线虫寄生？2)一个苍蝇物种中细菌的存在如何影响其他苍蝇物种的线虫寄生率？3)在什么条件下细菌可以传播到新的苍蝇物种？这项研究在公共卫生和农业领域具有潜在的更广泛的影响。丝虫引起人类丝虫病(河盲症)和淋巴丝虫病，目前全球约有1.6亿人感染。这些线虫通过昆虫媒介从一个人传播到另一个人。如果特定的细菌对昆虫媒介内的线虫产生不利影响，则有可能将这种细菌引入这些昆虫的种群中，从而减少某些疾病的传播、流行和严重程度。作为一种潜在的农业应用，细菌或从细菌衍生的基因可以被引入作物中，以提供对根结线虫的抗性，这种线虫每年在世界各地造成超过1200亿美元的农业损失。拟议的工作包括几个适合本科生研究的项目。PI将与罗切斯特大学的卡恩斯中心合作，招收低收入、第一代和代表性不足的少数族裔学生。

Most insect species on earth carry specific bacteria that are passed from infected females to their offspring. Many of these bacteria are beneficial to their hosts in such ways as conferring resistance to pathogens. Because insects are important members of larger ecological communities, the bacteria they carry may affect the structure and dynamics of these communities. The proposed research will examine several community-level effects of specific bacteria that infect specific mushroom-feeding flies. The bacteria living inside flies confer resistance to the sterilizing effects of a parasitic nematode worm and thus increase the fitness of parasitized flies. In addition, the bacteria dramatically affect the population dynamics of these parasitic nematodes: nematode parasitism increases rapidly in fly populations that lack bacteria, but the nematodes quickly go extinct in bacteria-infected populations. This project will investigate three questions: 1) How do bacteria affect the relative abundance of various species of competing flies, both in the presence and absence of nematode parasitism? 2) How does the presence of bacteria in one fly species affect the rate of nematode parasitism in other fly species? 3) Under what conditions can bacteria spread to new fly species?This research has potential broader impacts in the areas of public health and agriculture. Filarial nematodes cause onchocerciasis (River Blindness) and lymphatic filariasis in humans, with about 160 million people currently infected worldwide. These nematodes are carried from one person to another by insect vectors. If specific bacteria adversely affect nematodes within insect vectors, it might be possible to introduce the bacteria into populations of these insects and thus reduce the transmission, prevalence, and severity of certain diseases. As a potential agricultural application, bacteria or genes derived from them could be introduced to crop plants to provide resistance to root-knot nematodes, which annually cause over $120 billion in agricultural damage around the world. The proposed work includes several projects suited to undergraduate research. The PI will work with the Kearns Center at the University of Rochester to recruit low-income, first-generation, and underrepresented minority students.