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。农业病虫害防治是研究得特别充分的一个方面，众所周知，鸟类和蝙蝠等动物每年每公顷为农民节省数百美元。然而，动物可能提供的一项经常被忽视的生态系统服务是昆虫病媒的消费，这实际上可能会拯救生命。蚊子等作为媒介的昆虫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了作用。仅这些疾病每年就造成60多万人死亡，此外还有数亿感染这些疾病但后来康复的人遭受痛苦，以及护理这些疾病和丧失生产力的经济负担。通过昆虫媒介传播的其他疾病可能改变生命(例如寨卡病毒)。在控制蚊子等媒介方面取得了一些进展，特别是通过使用杀虫剂。然而，杀虫剂可能会产生负面结果，例如杀死关键的作物传粉者，损害食虫鸟类等食物网的其他成员，而且有证据表明，媒介可以而且确实会产生抗药性。对媒介昆虫的天敌知之甚少。例如，众所周知，蝙蝠是蚊子的贪婪消费者，每小时可能从环境中清除多达600只蚊子，但尚不清楚它们可能吃掉的是哪种物种(病媒或相对无害的物种)。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15种蝙蝠和鸟类消耗来自五个不同属的蚊子，包括按蚊、库蚊、Coquillettidia、Eretmapodites和Mansonia，这些蚊子包括重要的人类疾病媒介。然而，我们的数据仍然不完整，因为用目前的方法很难对昆虫媒介进行物种水平的分类。因此，该项目的目标是：1)与项目合作伙伴合作，开发一种DNA元编码系统，能够在物种水平上识别媒介昆虫；2)使用新开发的方法来识别消费昆虫媒介的动物--重点关注鸟类和蝙蝠，但可能也包括两栖动物、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，以回答以下问题：如果一个或多个捕食者被移走(例如，由于土地利用或气候变化)，会发生什么？如果将一个或多个媒介物种从系统中移除(例如，由于媒介控制策略)，会发生什么情况？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，学生将进行文献回顾并使用公共数据库来寻找潜在的遗传区域，这些区域具有足够的分辨率来识别昆虫媒介的物种水平分类，并设计/测试来自这些区域的候选元编码聚合酶链式反应引物。一旦开发出一套引物，并使用项目合作伙伴开发的一套引物，学生将使用先进的DNA测序技术对鸟类、蝙蝠以及可能的两栖动物、爬行动物和捕食性昆虫样本进行DNA元编码(即同时对所有潜在的昆虫媒介猎物进行测序)。然后，这些序列将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。数据将在生态群落网络中进行分析，以及在我们目前正在开发的动态生态建模框架中进行分析，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