Effect of chlorfenapyr on cypermethrin-resistant Culex pipiens pallens Coq mosquitoes

Mixture may provide additional benefits over either insecticide used alone. Mixtures of 5 ng/ml chlorfenapyr and 500 ng/ml cypermethrin exhibited a slight synergistic effect on cypermethrin-resistant C. p. pallens with a synergism effect of 3.33, 6.84 and 2.34% after exposure for 24,48 and 72 h, respectively. This effect was lost when the chlorfenapyr concentration was increased to 10 or 20 ng/ml.