174 - Resistance Bottle Bioassays: We may have a problem… now what?

Abstract: In 2024 the Canyon County Mosquito Abatement District implemented an insecticide resistance testing program. Initial testing was performed utilizing standard CDC bottle bioassays with Culex pipiens reared from egg rafts that were collected from sites throughout Canyon County, Idaho. The five active ingredients evaluated initially were malathion, sumithrin, permethrin, pyrethrum, and etofenprox. Results from the initial bottle bioassays indicated likely resistance in our wild type Cx. pipiens population for all active ingredients except malathion and permethrin. To further evaluate product efficacy, we conducted a caged field trial on additional reared Cx. pipiens with formulated product containing etofenprox as its active ingredient to assess formulated product efficacy. Due to unforeseen issues during the caged field trail, and weather changes impeding our ability to perform additional replicates with formulation, we moved to a modified bottle bioassay utilizing formulated product to determine efficacy. Results of our initial laboratory and field insecticide resistance testing assays will be presented.