This is a pilot study to investigate the potential impacts of green stormwater infrastructure on the ecology and management of mosquito vectors of West Nile Virus (WNV) in urban ecosystems. WNV has caused the largest arboviral encephalitis epidemic in U.S. history, and the propensity of urban stormwater structures to support large populations of the vectors Culex pipiens and Cx. restuans has contributed to these epidemics. At present, suppression of vector populations via the delivery of larva-specific insecticides (i.e. larvicides) to urban stormwater structures is one of the primary strategies for prevention and management of WNV epidemics. However, despite this widespread strategy, mosquito and WNV outbreaks continue to be a pressing public health challenge in urban ecosystems. While the field of stormwater management is rapidly evolving to include Green Infrastructure (GI) tools that reduce the volume of runoff and contaminants entering municipal storm and septic sewer systems, scant attention has been paid to how these changes will influence vector production, vector control and ultimately human risk of exposure to mosquito-borne pathogens. This project will take advantage of two natural experiments to quantify how replacement of traditional storm water catch basins with infiltration catch basins (I-CBs) and rain gardens associated with catch basins (RG-CBs) will affect the ecology and management of mosquito vectors in the City of Aurora, IL. Our overall aims are to a) determine if GI infrastructure tools (I-CBs and RG-CBs) accumulate or retain an insufficient volume of water to allow juvenile mosquitoes to complete development; b) determine if GI infrastructure tools increase the efficacy and duration of a sustained-release larvicide formulation; and c) determine if the neighborhood-scale implementation of a GI tool reduces the abundance of adult vector mosquitoes. The findings from this study may provide new insights for understanding the potential of GI practices to complement Integrated Vector Management practices in urban ecosystems by: a) reducing the quantity or quality of habitats suitable for mosquito development (i.e. source reduction), b) extending the efficacy of sustained-release larvicides used to control mosquito development in catch basins, and c) diminishing public health risks from exposure to insecticides and to vector- borne pathogens.
The ongoing stormwater infrastructure improvement projects in the City of Aurora, IL, offer an unprecedented and timely opportunity to investigate the large-scale conversion of conventional stormwater management practices to Green Infrastructure (GI) tools on the management and control of mosquito species responsible for transmission of West Nile Virus (WNV) to humans across large regions of the United States. Current trends suggest that the role of GI tools in urban stormwater management in the United States will likely continue to increase. It is therefore critically important that we understand how these changes to urban hydrology can complement and potentially lessen the use of conventional approaches (i.e. insecticides) so that public health risks associated with WNV and other mosquito-borne pathogens may be minimized in the safest, most cost-effective and environmentally responsible manner.
