Dose-Effects of Bednets Impregnated with a Natural Pyrethrins Formulation: Persistence, Feeding Inhibition, and Wash Resistance against Anopheles gambiae ss

Abstract

This study evaluated dose-response, persistence, irritancy and wash resistance of mosquito nets treated with a synergized natural pyrethrins-formulation against Anopheles gambiae ss Methods. Multi-filament polyester netting was impregnated to deposit doses of pyrethrins equivalent to 75 mg/m2, 100 mg/m2, 250 mg/m2, 500 mg/m2, and 1000mg/m2. Dose-response, persistence, and wash resistance were determined by a 3- minute cone bioassay on three-day-old female A. gambiae ss and residual-insecticide persistence was assessed in modified WHO bioassay tunnels and HPLC, respectively. Results. Interaction between dose and time post-exposure to treated net on knockdown (KD) and mortality of mosquitoes was significant (P= 0. 0001). Significant likelihood ratio (χ2= 33. 23, P= 0. 00266) confirmed post-exposure time effect on KD. Unwashed pyrethrins …