RESUMEN
The black saltmarsh mosquito, Aedes taeniorhynchus, is a prominent nuisance mosquito within St. Johns County, Florida. Due to their characteristically large outbreaks, and the elevated amount of insecticide application correlated with the outbreaks, local populations of Ae. taeniorhynchus are at an increased risk of developing insecticide resistance. This study was established to form a baseline susceptibility of Ae. taeniorhynchus against two technical grade materials, permethrin, and chlorpyrifos. Centers for Disease Control and Prevention bottle bioassays were conducted with technical-grade materials during two outbreaks in the fall of 2023. Results indicated a baseline susceptibility against the materials tested, but most notably, the phenotypic expression of knockdown resistance (kdr) was observed. Results highlight the need for continued monitoring and investigation into the resistance status and resistance level of this common Florida species.