The ecology of host-pathogen interactions in Lepidoptera

了解影响特定物种密度和分布的因素，对于我们管理生物多样性和开发保护作物和人类种群的可持续方法至关重要。病原体是所有生态系统的关键组成部分。我们知道病原体可以对生存产生重大影响，但它们在动物种群中的作用和对群落结构的影响却知之甚少。本计划的重点是一组病原体，杆状病毒，这是常见的几种昆虫，也已开发作为害虫防治剂。我们使用两种模型系统来研究病毒感染；西部帐篷毛虫（Malacosoma californicum pluviale）和卷心菜环虫（Trichoplusia ni）。帐篷毛虫经常出现在初夏的落叶树上，当它们的数量很多时，它们通常会被一种攻击毛虫阶段的杆状病毒杀死。卷心菜环虫是一种以芸苔属植物为食的物种，每年迁徙到加拿大，是田间和温室作物的主要害虫。利用这两个系统，我们将确定决定昆虫抗性和病原体毒力的因素，并探索遗传变异在宿主-病原体相互作用中的作用。我们的目标是了解昆虫的饮食对疾病的易感性是如何影响的；昆虫是否更容易受到某些植物物种的伤害？我们知道病毒在基因上是可变的，我们想知道这是如何影响它们与宿主的相互作用的。我们怀疑涉及许多遗传株的病毒感染更具致病性。我们想在自然人群中测试这个想法。这项研究的独特之处在于，它使用了来自空间上分离的寄主群体的长期数据信息，这些寄主群体定期经历高水平的感染。这些结果将对了解影响杆状病毒生态学和进化的因素具有广泛的意义，可以指导改进害虫防治计划的发展。总的来说，这些研究的见解将确定哪些成分影响宿主抗性和病原体毒力的变化，遗传多样性如何影响疾病严重程度，以及环境因素对调节疾病风险的影响。

Understanding what influences the density and distribution of a particular species is fundamental to our ability to manage biodiversity and to develop sustainable methods for protecting crops and human populations. Pathogens are key components in all ecosystems. We know that pathogens can have major impacts on survival but their roles in animal populations and impacts on community structure are poorly understood. This program focuses on one group of pathogens, the baculoviruses, which are common in several groups of insects, and also have been developed as pest control agents. We are using two model systems for the study of viral infection; the western tent caterpillar, Malacosoma californicum pluviale and the cabbage looper, Trichoplusia ni. Tent caterpillars are often seen on deciduous trees in early summer and when their numbers are high they are often killed by a baculovirus which attacks the caterpillar stage. The cabbage looper is a brassica-feeding species which migrates into Canada each year and can be a major pest on both field and greenhouse crops. Using these two systems we will identify the factors that determine insect resistance and pathogen virulence and explore the role of genetic variation in host-pathogen interactions. Our goal is to understand how susceptibility to disease is influenced by an insect's diet; e.g. are insects more vulnerable on certain plant species? We know that the viruses are genetically variable, and we want to understand how this affects their interactions with the host. We suspect that virus infections involving many genetic strains are more pathogenic. We want to test this idea in a natural population. This study is unique in that it uses information from long-term data from spatially separated host populations that periodically experience high levels of infection. These results will have broad implications in that understanding the factors that influence baculovirus ecology and evolution could guide to the development of improved insect pest control programs. Overall, insights from these studies will identify what components influence changes in host resistance and pathogen virulence, how genetic diversity influences disease severity, and the influence of the environmental factors on modulating the risk of disease risk.