The ecology of host-pathogen interactions in Lepidoptera

点击翻译按钮获取中文摘要

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.