The bionomics of pesticide-resistant strain of Culex pipiens pallens

Experimental observations showed that the pupation rates of susceptible strain of Culex pipiens pallens were remarkably higher than those of DDVP-resistant and the Cypermethrin-resistant strains with χ2=25.98 and 20.64,P0.05 in χ2 test,respectively.While the larval period of the pesticide-resistant strains was slightly shorter than that of the sensitive strain.Sub-lethal dosage of Cypermethrin had obvious effects on the pupations of Cypermethrin-resistant strain and the Ⅲ-Ⅳ-stage larvae of susceptible strain of Culex pipiens pallens and the longevity of the resistant strain was slightly prolonged.All these results suggested that mosquito resistance to pesticides is easily developed when a single pesticide is repeatedly used.