Spiroplasma infection and tolerance of nematode parasitism in Drosophila

大多数种类的昆虫被共生微生物感染，这些微生物通过直接使其宿主受益或通过以有利于共生体而不是宿主的方式操纵宿主繁殖来传播。 细菌螺原体是这些共生体中分布较广的一种。 迄今为止发现的所有螺原体要么操纵宿主繁殖，要么对其昆虫宿主具有致病性。 在果蝇（Drosophila neotestacea）种群中，已发现螺原体赋予对线虫寄生的抗性。 在野外，寄生的苍蝇如果不携带螺原体，基本上会被线虫绝育，但如果感染了这些共生体，它们的生育能力几乎正常。这是第一次发现螺原体对任何昆虫物种的有益影响，也是第一次证明螺原体对线虫的不利影响。螺原体感染D.在过去的20年里，美国东部的新龟科动物似乎迅速增加，并可能向西传播。 本计画将进行实验，以测试线虫寄生对螺原体感染动态的影响。新壳纲 反过来，还将检测螺原体对这些果蝇中线虫寄生的影响。 虽然D.虽然北美东部的新壳纲果蝇感染了螺原体，但落基山脉以西的果蝇没有一只感染。 该项目将对不列颠哥伦比亚省和加拿大大草原省的人口进行抽样，以评估螺原体是否正在北美向西传播。螺原体的生育力恢复效果也将在果蝇和线虫物种的其他组合中进行测试。 如果是普遍的，这种效应可能具有很大的应用意义。 河盲症和象皮病是由黑蝇和蚊子传播的丝虫线虫引起的。 如果螺原体赋予对丝虫线虫的抗性，那么螺原体可以在昆虫媒介的种群内传播，这可能会减少线虫的繁殖，从而减少丝虫病的发病率和严重程度。 原则上，对昆虫媒介进行相对简单的操作就可以产生巨大的公共卫生效益。 该项目将为本科生和研究生提供研究培训。

Most species of insects are infected by symbiotic microorganisms, which spread either by directly benefiting their hosts or by manipulating host reproduction in ways that benefit the symbiont, but not the host. Bacterial Spiroplasma are among the more widespread of these symbionts. All Spiroplasma discovered to date either manipulate host reproduction or are pathogenic to their insect hosts. In populations of the fruit fly, Drosophila neotestacea, Spiroplasma have been found to confer resistance to nematode parasitism. Parasitized flies in the wild are essentially sterilized by the nematode if they do not carry Spiroplasma, but have nearly normal fertility if they are infected with these symbionts. This is the first finding of a beneficial effect of Spiroplasma on any insect species, and the first demonstration of an adverse effect of Spiroplasma on nematodes. Spiroplasma infection in D. neotestacea appears to have increased rapidly in the last 20 years in the eastern US and may be spreading westward. This project will conduct experiments to test for the effect of nematode parasitism on Spiroplasma infection dynamics within populations of D. neotestacea. Reciprocally, the effect of Spiroplasma on nematode parasitism in these flies will also be tested. Although most individuals of D. neotestacea in eastern North America are infected with Spiroplasma, none of the flies west of the Rockies are infected. This project will sample populations in British Columbia and Canadian Prairie Provinces, that were last sampled in 2002, to assess whether Spiroplasma is spreading westward across North America. The fertility-restoring effect of Spiroplasma will also be tested on other combinations of Drosophila and nematode species. If general, such effects could be of great applied significance. River Blindness and Elephantiasis are caused by filarial nematodes that are transmitted by blackflies and mosquitoes. If Spiroplasma confers resistance to filarial nematodes, then Spiroplasma could spread within populations of the insect vectors, which might reduce nematode reproduction and thus incidence and severity of filarial diseases. In principle, a relatively simple manipulation of the insect vectors could yield great public health benefits. This project will provide research training for undergraduate and graduate students.