Effectiveness of a permethrin-treated barrier and pour-on applications against Culicoides spp. (Diptera: Ceratopogonidae) and mosquitoes (Diptera: Culicidae) on a deer farm.

Abstract

Culicoides biting midges (Diptera: Ceratopogonidae) and mosquitoes (Diptera: Culicidae) are important vectors of pathogens affecting ruminants. On deer farms, Culicoides species transmit bluetongue virus and epizootic hemorrhagic disease virus, while mosquitoes can cause chronic stress and even exsanguination. We evaluated the effectiveness of the insecticide -InsectGuard (0.5% permethrin), applied as a barrier treatment and pour-on, to reduce mosquito and biting midge landings on deer in Martin County, Florida. Deer simulators baited with carbon dioxide and fitted with sticky cards were used to trap landing insects. A polyethylene fence barrier treated with InsectGuard (1.34 fl oz/m2) and an untreated fence were tested against a no-barrier control. Separately, InsectGuard pour-on (1 fl oz per deer) was compared to an untreated control. The -InsectGuard-treated barrier and pour-on applications reduced landings of three Culicoides species, including Culicoides insignis Lutz, a key bluetongue virus vector, by 175-fold and 7-fold, respectively. The InsectGuard-treated barrier also reduced mosquito landings: Culex spp. (15-fold), and Psorophora spp. (6-fold). While the InsectGuard pour-on caused a dramatic reduction of C. insignis, it had no measurable effect on Culex spp., Psorophora spp., or Culicoides floridensis Beck and appeared to attract Culicoides pusillus Lutz (8-fold increase). Our findings demonstrate that permethrin-treated barriers and pour-on applications can reduce the landing and, therefore, potential infectious bites of mosquitoes and biting midges. These interventions can be incorporated as part of an integrated vector management program for deer farms to enhance control outcomes, in combination with other strategies such as adulticide sprays, habitat management, and vaccination.