Efficacy of Resmethrin Aerosols Applied from the Road for Suppressing Culex Vectors of West Nile Virus

We determined whether aerosol applications of resmethrin, delivered from the road, suppress the reproductive activity of Culex pipiens pipiens and Cx. restuans mosquitoes in suburban sites located near Boston. Oviposition implies a prior blood-feeding event and hence a potential West Nile virus (WNV) transmission-related event. Droplet size, rate of delivery and meteorological conditions were monitored. The target populations proved to be fully susceptible to the insecticide that was used. The roads in the test sites generally gave adequate opportunity for insecticidal coverage. We found that the aerosol plume may have failed to contact the target mosquitoes and conclude that such insecticidal aerosols, delivered from the road, may not effectively reduce the force of trans-mission of WNV in our test sites. Key Words: Mosquito control—Adulticide—ULV—Resmethrin—Culex pipiens pipiens—Culex restuans—Arbovirus—West Nile virus. Vector-Borne Zoonotic Dis. 6, 117–127. 11