With collaborators (Calder, Doran, Marra) Dr. Shannon LaDeau has quantified and used dramatic declines in abundance of this susceptible avian host as a proxy for WNV activity to explicitly examine heterogeneity in WNV intensity over a broad spatial range and across multiple land cover types. Population-wide estimates of American crow abundances declined an average 30% after the emergence of WNV. However, the spatial pattern of where individual crows were lost varied considerably. They documented significant declines in crow abundance after WNV emergence at 15% of Breeding Bird Survey (BBS) sites across the eastern United States. Generally, locations with more area under human development and less forested area were associated with higher odds of WNV impact.
The potential effects of landscape modification and interactions with changing climate on pathogen dynamics are complex, and likely to alter the ecological processes that define spatio-temporal patterns in composition and abundance of mosquito species and human disease risk.
In collaboration with Dr. John Wallace (Millersville University), LaDeau has begun field work in conjunction with the Baltimore Ecosystem Study, to test the hypothesis that urban breeding habitats support fewer mosquito species but greater abundances of vector species. She has identified ten mosquito species across the Gwynns Falls watershed in Baltimore. Four occurred in both urban and rural samples, while three potentially important bridge vectors (mosquitoes that feed on both birds and humans) were found only in urban sites (Aedes vexans, Aedes albopictus, Ochlerotatus japonicas).