John Vinson (1), and Andrew Park (1, 2)
(1) Odum School of Ecology, University of Georgia (2) Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia
With global changes in diversity an understanding of how decreased host diversity will affect disease transmission is crucial. The dilution effect hypothesis posits that decreased host species diversity may lead to an increase in disease risk. Evidence for the phenomenon has been observed in both West Nile virus (WNV) and Lyme disease systems, which are transmitted through vector species. However, there remains an opportunity to explore the generality of the relationship for vector borne pathogens under both community disassembly and host species phenology. We present a multi-host SI model with vector-borne transmission, and explore the conditions under which decreased disease risk occurs, using the reproductive ratio (R0) of the parasite. We derive conditions for changes in R0 with host richness under scenarios where the one community is a subset of another (e.g. community disassembly, or changes due to loss/gain of migratory species). We explore predictions using a WNV case study using data on bird and mosquito abundance in Central Park, New York. Phenology in bird abundance coupled with mosquito emergence through the year combine to provide a peak period of infection risk, which corresponds to peak disease reporting following a five week shift. These results provide a potential method for predicting change in disease risk following predictable community disassembly, including migration.