Permethrin Susceptibility for the Vector and a Nuisance Mosquito in an Area Endemic for West Nile Virus.

In 2016, we compared susceptibility to the insecticide, permethrin, between the West Nile virus vector, Coquillett, and a major nuisance mosquito, (Meigen), using baseline diagnostic dose and time values determined using the CDC bottle bioassay protocol. Mosquitoes were collected in the wild in Brookings County, South Dakota, situated in the Northern Great Plains of the USA. The determined diagnostic dose and time were then used in 2017 to validate these measurements for the same 2 mosquito species, collected at a second location within Brookings County. The diagnostic dose was determined for multiple time periods and ranged from 27.0 g/ml at 60 min to 38.4 g/ml at 30 min. There was no significant difference detected in mortality rates between and for any diagnostic time and dose. For practical purposes, mosquitoes in 2017 were tested at 38 g/ml for 30 min; expected mortality rates were 93.38% for and 94.93% for Actual 2017 mortality rates were 92.68% for and 96.12% for , validating the usefulness of this baseline at an additional location and year.