D3036: Elucidating the importance of fine-scale vector behaviors in seasonal plant virus epidemics using a variance-based sensitivity analysis of the tomato spotted wilt virus pathosystem

The vector manipulation hypothesis describes how viruses may manipulate various insect vectors’ host-preference behavior, and has been shown to be both empirically and theoretically important to the epidemiology of insect-vectored plant pathogens. However, host preference arises from a complex suite of correlated behaviors which dictate transmission events. This begs the question: which fine-scale behavioral traits have the highest influence on the rate of virus spread over the course of a season? To explore this question, I created a behaviorally explicit mathematical model for the spread of Tomato spotted wilt virus (TSWV) by western flower thrips (Frankliniella occidentalis), and performed a variance-based global sensitivity analysis that spanned a growing season. This model makes assumptions that relate preference, foraging, and transmission with each other. Furthermore, dispersal and feeding behavior are assumed to be affected by changes in host suitability. In this context, these behaviorally explicit assumptions allow us to better understand how the spread of TSWV over time is impacted by seasonal changes in host quality. Here, a relationship emerges between infection dynamics and the degree to which host plant phenology drives changes in insect behavior over the course of a growing season. This model may facilitate our understanding of how selection pressure on the evolution of the vector-virus relationship changes throughout a growing season, and preliminary model results suggest the vector manipulation hypothesis should be broadened to include how viruses may manipulate vectors’ time-budgeting on hosts, not just host-preference behavior.