Meeting Abstract
Parasite transmission dynamics depend on interactions between host and vector traits within the context of the environment. For example, host behavior and physiology mediate parasite exposure, susceptibility and infectiousness, and vector feeding preferences can influence which individuals contribute most to the spread of infections. Importantly, host defenses and vector preferences might change plastically across an environmental gradient, for example, through effects of natural and anthropogenic change on the endocrine system. Glucocorticoid hormones profoundly affect vertebrate immunity and behavior and may thus influence how hosts encounter and respond to parasites and vectors. We investigated the role of stress hormones in mediating the enzootic cycle between mosquitoes and birds in the West Nile virus (WNV) system. Adult zebra finches (Taeniopygia guttata) were experimentally manipulated via corticosterone (CORT) implants to examine role of stress hormones in shaping (1) anti-vector behaviors of hosts (2) vector preferences for hosts and (3) WNV viremia profiles. Birds implanted with CORT did not display significant differences in anti-vector behaviors directed toward the southern house mosquito (Culex quinquefasciatus) compared to controls. However, implantation with CORT nearly doubled the chances that a bird was fed on by vectors. Additionally, mortality rate was increased in the CORT-treated birds compared to controls. Our findings suggest that corticosterone and other hormones may mediate plasticity in host traits, which could amplify the contributions of some individuals to transmission dynamics. Such effects might be especially common where anthropogenic stressors are concentrated such as cities and other highly-modified habitats.
