The Role of Host-Pathogen Coevolution in the Population Dynamics of an Insect-Virus Interaction

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0075461DwyerMost recent approaches to understanding host-pathogen interactions assume that host-pathogen population dynamics and host-pathogen co-evolution are separate subjects. Moreover, host-pathogen co-evolution is often assumed to be about pathogen virulence, rather than about host resistance or true co-evolution. In previous research on the interaction between gypsy moth and its virus, however, the PI has collected data showing that host variability in resistance to the virus plays an important role in gypsy moth outbreaks, and the preliminary attempts to model this system have suggested that the evolution of resistance may drive gypsy moth outbreaks. Thus, it seems likely that the evolution of resistance and fluctuating population densities are key to understanding the interaction between the gypsy moth and its virus, while the evolution of pathogen virulence may be important largely because it helps to maintain variability in host resistance. This research will investigate the following questions: Does host resistance drive population outbreaks in the gypsy moth? How is variability in host resistance maintained? The approach to answer these questions will be to document changes in host resistance and pathogen virulence in several outbreaking gypsy moth populations, during the period while these populations are collapsing because of virus epidemics. In addition, we will quantify additive genetic variability in virus resistance in the gypsy moth, to understand the potential for evolutionary changes in this insect. Also, we will explore whether host-pathogen specificity and/or fitness tradeoffs in host and pathogen can help to maintain host resistance. This will serve to unite the two previously disparate fields of population dynamics and evolutionary dynamics, and may shed light on strategies to manage this pest insect.