106 - The Big Picture – impact of IR testing on WNV Control decisions

Abstract: Recently, investigations into the effectiveness of truck-mounted ULV sprays in the Chicago area suggest that even at full label rate these sprays may yield less than ideal results in local Culex mosquitoes. Additionally, rebounds in Culex abundance above pre-spray levels after a temporary decrease have been consistently observed with these sprays. By leveraging resources from the CDC, subsequent IR bottle bioassays have helped to explain why achieving optimum results with these sprays are challenging . Bioassays performed in and around the Chicago area have confirmed resistance to nearly every active ingredient available, including pyrethrum, deltamethrin, permethrin, sumithrin, and malathion. With this information in hand, the North Shore Mosquito Abatement District has transitioned away from routine ULV sprays to better conserve this tool as a public health response and, concurrently, has added other tools to target larval stages of nuisance and vector mosquitoes. The bottle bioassays will continue to be a useful resource for local programs in the Chicago area.