PS 6-78 - CANCELLED - Eco-Evolutionary effects of climate change on host-pathogen interactions: Is it getting warm in here or did I catch something?

Abstract: Global climate change has altered established species dynamics including species distributions, community assemblages, and species interactions. Of particular concern in a warming environment are host-pathogen interactions. Past research has shown that changes in the host-pathogen interactions may either increase or decrease disease transmission depending on the environment and species involved. However, there is still a large knowledge gap regarding how ecological, evolutionary, and coevolutionary dynamics of a host and its pathogen are affected by climate change. We use an established and easily manipulated insect-pathogen system, the fall armyworm (Spodoptera frugiperda) and its species specific baculovirus to examine how a changing climate affects the eco-evolutionary dynamics of a host-pathogen interaction. The host is an agricultural pest that has spread across several continents and its virus is a lethal pathogen, which is also considered a potential bioinsecticide. First, host performance was quantified through the construction of a thermal performance curve across several temperatures. Using a series of dose-response experiments, one line of the host was then laboratory culled using a lethal dose at which 50 percent of the previous generation would have died from becoming infected with the virus (i.e. LD50). A separate line was established as a control and not exposed to the virus. Additionally, we quantified hemocyte production of the host and pathogen production in the virus exposed hosts. Separate host lines were then reared at different temperatures and either not exposed to the virus or continually exposed to the virus every generation. The data show that temperature affects the development and survival of the host. Development time decreases and, at a certain point, survival decreases as temperature increases. Host susceptibility to the virus depends on temperature such that at a low developmental temperature susceptibility does not change. At a warmer temperature, susceptibility decreases over multiple generations for a coevolved host and pathogen. Given the use of the virus as a bioinsecticide and the recent invasion of both Africa and Asia by the fall armyworm, the results are widely applicable to agricultural pest management and invasive species control. In particular, the use of natural enemies in the form of species-specific pathogens help control pest populations in the face of expanding habitat ranges of pest species. But, the efficacy of these results may depend on the degree to which the planet warms. Future research directions include examining how changes in susceptibility in conjunction with different temperature regimes affect disease transmission dynamics.