Environmental And Ecological Factors Influencing Insect-Borne Virus Epidemiology
Vector ecology is essential to understanding the epidemiology of insect-borne pathogens. Yet, while much is known about vector population ecology, little work has been done on the impact of vector community ecology on disease spread. In my doctoral research, I studied environmental and ecological factors that influence the spread of a non-persistent plant pathogen, potato virus Y (PVY), focusing on the effect of landscape composition and the aphid vector assemblage on disease transmission. Chapter 1 shows that landscape composition within 1500m of a site strongly affects PVY prevalence; higher PVY prevalence was found in landscapes with greater amounts of agriculture. The work in this chapter also indicates that the effect of the landscape on PVY prevalence is most likely mediated by the direct effect of the landscape on the aphid vector community. Chapter 2 demonstrates that landscape composition and intra-annual variation interactively affect the aphid community in two cropping regions. Chapter 3 explores the effect of aphid density and community composition on aphid movement and PVY transmission. I found that aphid density positively affected aphid movement, and that conspecific density was more predictive than heterospecific density. Community composition affected both aphid movement and virus transmission, and these effects were driven by species identity, rather than species richness per se. Chapter 4 assessed the impact of predation and host plant abundance and spatial distribution on the movement of a common non-colonizing aphid species and PVY transmission. Predation, host plant abundance, and plant spatial distribution interactively affected viral prevalence. Increasing the number of vector non-host plants increased the distance and frequency of aphid movement, and the effect was influenced by plant spatial distribution. However, aphid movement did not appear to mediate the effect of plant and predator treatments on PVY prevalence. Collectively, this work demonstrates the importance of vector community ecology and landscape epidemiology on insect-borne plant pathogens.
agroecology; landscape epidemiology; disease ecology
Ph. D., Entomology
Doctor of Philosophy
dissertation or thesis