The ecology and evolution of insect pathogens

为了能够有效地管理环境，无论是在保护生物多样性，保护我们的作物免受害虫侵害还是维护人类健康方面，我们需要了解不同的生物体如何相互作用，以及我们观察到的模式背后的机制是什么。我们环境的关键组成部分之一是病原体，它们在几乎所有的植物和动物群体中引起不同严重程度的疾病。这个项目将重点研究一种昆虫，西部帐篷毛虫和一种病毒病原体之间的相互作用。帐篷毛虫经常在初夏的落叶树上出现，然而，当它们的数量很高时，它们经常被一种攻击毛虫阶段的病毒疾病杀死。这种疾病被认为在这种昆虫每8-11年的种群波动中起着重要作用。在这个节目中，我们将研究在不列颠哥伦比亚省温哥华附近发现的几种帐篷毛虫种群。我们对这种相互作用的演变特别感兴趣：昆虫对病毒的抵抗力是否会随着病毒密度的变化而改变，以及病毒种群如何根据其毒性对此作出反应。我们不仅对记录数字感兴趣：我们还想研究这种相互作用的遗传学，以及不同水平的遗传变异在结果中所起的作用。我们早期的研究表明，病毒种群在遗传上是高度可变的，这受到不同种群的空间结构的影响。我们想要回答的一个问题是为什么病毒种群如此多变？我们怀疑由许多密切相关的病毒株组成的感染比任何单一的病毒株更具有致病性。然而，我们希望能够在自然人群中测试这个想法，并理解为什么更多的病毒比一个病毒好。我们还想了解病毒感染如何影响昆虫的基因，例如，在种群周期中，昆虫是否更容易受到感染，其基础是什么？该项目的研究结果不仅将对野生动物种群中病原体的作用产生影响，而且还将对了解人类疾病和农业相关病原体的疾病严重程度的发展产生影响。

In order to be able to manage the environment effectively, either in terms of preserving biodiversity, protecting our crops from pests or maintaining human health, we need to understand how different organisms interact and what mechanism underlie the patterns we observe.  One of the key components of our environment is the pathogens that cause diseases of varying severity in virtually all groups of plants and animals.  This programme will focus on the interactions between an insect, the western tent caterpillar, and a virus pathogen.  Tent caterpillars are often seen on deciduous trees in early summer however, when their numbers are high they are frequently killed by a virus disease which attacks the caterpillar stage.  This disease is thought to play an important role in the population fluctuations that are so evident in this insect every 8-11 years.  In this programme we will study several tent caterpillar populations found in the vicinity of Vancouver, BC.  We are particularly interested in the evolution of this interaction: whether the resistance of the insect to the virus alters as it changes in density, and how the virus population responds to this in terms of its virulence.  We are not just interested in recording numbers: we also want to study the genetics of the interaction and the role that different levels of genetic variation play in the outcome.  Our earlier research has shown that the virus populations are highly variable genetically and that this is influenced by the spatial structure of the different populations.  One of the questions we want to answer is why is the virus population so variable?  We suspect that infections made up of many closely related virus strains are more pathogenic than any single strain.  However, we want to be able to test this idea in a natural population and to understand why it is that more viruses are better than one.  We also want to understand how infection by the virus affects the genetics of insect, for example, are there times in the population cycle when the insects are more susceptible and what is its basis? The findings from this project will have implications, not only for the role of pathogens in wildlife populations, but also in terms of understanding the development of disease severity in human diseases and pathogens of agricultural interest.