Evaluation of Chlorfenapyr applied as an IRS for control of pyrethroid resistant Anopheles gambiae and Culex quinquefasciatus: a household randomized trial in southern Benin

This study assessed whether the efficacy of a moderate dosage (250mg/m²) of chlorfenapyr applied as IRS within rural Beninese villages could rival that of the standard pyrethroid alphacypermethrin (25mg/m²) or the carbamate bendiocarb (400mg/m²) currently deployed for IRS in area with high pyrethroid resistance. The results indicated a steady decay of all 3 treatments over time in terms of personal protection and mortality of An. gambiae. The comparative performance within local huts in southern Benin and through bioassays with 250mg/m² chlorfenapyr IRS indicated a shorter term gain in control of pyrethroid resistant mosquitoes than bendiocarb 400mg/m² or alphacypermethrin 25mg/m². Instead, the bioassay data suggest that higher chlorfenapyr dosage, e.g. 500mg/m² or above would be ideal dosages to consider during spray campaigns in pyrethroid resistant areas. Comparative trials including 500mg/m² chlorfenapyr should be undertaken in experimental and at household level in similar areas with resistance.