Abstract: Documentation that adult mosquito control practices change Culex populations evidenced by entomological outcomes or epidemiological outcomes is inadequate and often contradictory. It is imperative to understand how adulticide applications interact with female mosquitoes at different gonotrophic stages so that a more targeted and efficacious approach can be utilized. We evaluated the impacts of multiple adulticide applications on Culex pipiens and Cx. restuans abundance, age structure, and West Nile virus infection over multiple years. Both host-seeking and gravid mosquitoes were collected daily from 24 residential properties, half of which were located within three large, treated sites. Adulticide was sprayed once per week for five sequential weeks during peak Culex abundance periods. Zenivex E20 and Anvil 10+10 were both used for adulticide, though resistance to both products was discovered. Analysis and WNV testing is on-going, though preliminary results show no reduction in mosquito abundance and a rebound effect several days later. We observed a significant decrease of parous mosquitoes in treated sites, reducing the risk for human WNV infection. Surprisingly, Cx. pipiens and Cx. restuans did not respond in the same way to adulticide application, highlighting the importance of differentiating the two species when possible.
