Understanding the role of Animals as preditors of disease

科学文献中的大量证据表明，生物多样性为人类提供了重要的生态系统服务。其中一个研究得特别好的方面是农业害虫控制，众所周知，鸟类和蝙蝠等动物每年每公顷可为农民节省数百美元。然而，动物可能提供的一个经常被忽视的生态系统服务是昆虫病媒的消耗，这实际上可以挽救生命。作为媒介的昆虫，如蚊子，是地球上最致命的动物，因为它们在疟疾，登革热，黄热病，非洲昏睡病等疾病的传播中发挥作用。仅这些疾病每年就造成60多万人死亡，此外还有数亿人感染这些疾病但随后康复，以及照顾他们的经济负担和生产力损失。由昆虫传播的其他疾病可以改变生命（例如寨卡病毒）。在控制蚊子等病媒方面取得了一些进展，特别是通过使用杀虫剂。然而，杀虫剂也可能产生负面影响，例如杀死主要的作物授粉者，伤害食虫鸟类等食物网的其他成员，而且有证据表明，病媒可以而且确实会产生抗药性。对病媒昆虫的天敌知之甚少。例如，众所周知，蝙蝠是贪婪的蚊子消费者，每小时可能从环境中清除多达600只蚊子，但目前尚不清楚它们可能会消耗哪些物种（疾病载体或相对良性的物种）。我们从喀麦隆收集的鸟类和蝙蝠粪便样本的DNA序列数据显示，至少有15种蝙蝠和鸟类消耗来自5个不同属的蚊子，包括按蚊，库蚊，Coquillettidia，Eretmapodites和Mansonia，其中包括重要的人类疾病载体。然而，我们的数据仍然是不完整的，因为它是非常困难的分配种级分类的昆虫媒介使用现有的方法。因此，该项目的目标是：1）与项目伙伴合作，开发一个DNA元条形码系统，可以识别病媒昆虫到物种水平2）采用新开发的方法来识别食用昆虫病媒的动物-重点是鸟类和蝙蝠，但也可能是两栖动物，爬行动物和捕食性昆虫3）使用网络和生态建模方法来调查这些物种参与的食物网，并进行敏感性分析，以回答这样的问题：如果一个或多个捕食者被移除（例如，由于土地使用或气候变化）会发生什么？如果一个或多个病媒物种从系统中消失（例如，由于病媒控制战略），会发生什么？学生将利用我们在喀麦隆，加纳和赞比亚正在进行的项目中收集的2000多个鸟类，蝙蝠和两栖动物样本。在实验室中，学生将进行文献综述，并采用公共数据库来寻找具有足够分辨率的潜在遗传区域，以确定昆虫载体的物种级分类，并设计/测试来自这些区域的候选metabarcoding PCR引物。一旦开发出一套引物，并使用项目合作伙伴开发的引物组，学生将使用先进的DNA测序技术对鸟类，蝙蝠和潜在的两栖动物，爬行动物和捕食性昆虫样品进行DNA元编码（即对所有潜在的昆虫载体猎物进行同步测序）。然后将这些序列与我们的参考序列数据库进行比较，以使用复杂的生物信息学管道进行分类。数据将在生态社区网络以及我们目前正在开发的动态生态模型框架中进行分析，以将物种相互作用和丰度联系起来

A mountain of evidence in the scientific literature suggests that biodiversity provides important ecosystem services for humans. One aspect that has been particularly well studied is agricultural pest control, where animals such as birds and bats are often known to save farmers hundreds of dollars per hectare per year. However, an often overlooked ecosystem service that animals may provide is the consumption of insect disease vectors, which may literally save lives. Insects that act as vectors, such as mosquitoes, are the deadliest animals on the planet, due to their role in the spread of diseases such as malaria, dengue fever, yellow fever, African sleeping sickness and others. These diseases alone account for more than 600,000 human deaths every year, in addition to suffering by hundreds of millions of people that contract the diseases but subsequently recover, and the economic burden of caring for them and lost productivity. Other diseases spread by insect vectors can be life altering (e.g. Zika virus). Some progress has been made in controlling vectors like mosquitoes, particularly through the use of insecticides. However, insecticides can have negative outcomes, such as killing key crop pollinators, harming other members of the food webs such as insectivorous birds, and evidence suggests that vectors can and do evolve insecticide resistance. Natural predators of vector insects are poorly understood. For example, bats are known to be voracious consumers of mosquitoes, potentially removing up to 600 from the environment every hour, but it remains unclear which species they may be consuming (disease vectors or those that are relatively benign). Our DNA sequence data from bird and bat faecal samples collected from Cameroon show that at least 15 species of bats and birds consume mosquitoes from five different genera, including Anopheles, Culex, Coquillettidia, Eretmapodites, and Mansonia, which include important human disease vectors. However, our data remain incomplete, because it is very difficult to assign species-level taxonomy to insect vectors using current methods. Thus, this project aims to:1) In collaboration with project partners, develop a DNA metabarcoding system that can identify vector insects to species level2) Employ the newly developed approach to identify animals consuming insect vectors - focusing on birds and bats, but potentially also amphibians, reptiles, and predatory insects3) Use network and ecological modeling approaches to investigate the food webs that these species participate in, and perform sensitivity analyses to answer questions such as: What would happen if one or more predators were removed (e.g. due to land use or climate change)? What would happen if one or more vector species were removed from the system (e.g. due to vector control strategies)? The student will leverage our massive collection of more than 2000 bird, bat, and amphibian samples already in hand from our on-going projects in Cameroon, Ghana and Zambia. In the lab, the student will conduct a literature review and employ public databases to find potential genetic regions with sufficient resolution to identify species-level taxonomy of insect vectors, and design/test candidate metabarcoding PCR primers from these regions. Once a suite of primers has been developed, and using a primer set developed by project partners, the student will conduct DNA metabarcoding of bird, bat, and potentially amphibian, reptile and predatory insect samples (i.e. simultaneous sequencing of all potential insect vector prey) using advanced DNA sequencing technology. These sequences will then be compared to our reference sequence database to assign taxonomy using sophisticated bioinformatics pipelines. Data will be analysed in ecological community networks as well as in a dynamic ecological modelling framework we are currently developing to link species interactions and abundances