Laboratory and field assays indicate that a widespread no-see-um, Culicoides furens Poey is susceptible to permethrin

The recent reemergence of Oropouche virus (OROV) highlights the need to better understand insecticide susceptibility in Culicoides (Diptera: Ceratopogonidae), which contains the vector of OROV and many other species that are biting nuisances and vectors of pathogens that affect humans, livestock, and wildlife. With adulticides as the primary method of Culicoides control, there is growing concern about insecticide resistance, compounded by the lack of tools to monitor Culicoides susceptibility. We adapted the CDC bottle bioassay and field cage trial methods, typically used to monitor insecticide susceptibility in mosquitoes and formulated adulticide efficacy, to evaluate permethrin susceptibility in the widely distributed coastal nuisance species, Culicoides furens . Permethrin caused complete mortality in C. furens in field and laboratory assays. We identified a diagnostic dose (10.75 µg) and time (30 minutes) that resulted in complete mortality in CDC bottle bioassays. Additionally, we determined that no-see-um netting is an effective mesh for field cage trials, allowing for accurate assessment of Culicoides susceptibility to ultra-low volume applications of formulated adulticides like Permanone 30–30, a widely utilized adulticide. These methodologies offer essential tools for assessing Culicoides susceptibility, which is crucial for managing populations of Culicoides and preventing the spread of OROV and other pathogens.