Field study on control of resistance of Culex pipiens pallens to propoxur in three localities of Shandong Province

Aim To survey of the resistance of Culex pipiens pallens to propoxur in three localities of Shandong Province and delay its resistance. Methods The susceptibility and synergism of Culex pipiens pallens collected from the cities of Tengzhou,Tai'an and t o propoxur and its mixtures with three synergists,Jining in Shandong were assayed was detected for the purpose of delaying and overcoming the occurrence and development of mosquito resistance. WHO standard bioassay method was employed to calulate LC50,regression equation and synergistic coefficients. Results The synergistic coefficients of propoxur mixed with S1 (Piperonyl butoxode),S2 (Octachlorodipropyl ether) and MGK-264 were 2.23-8.02,2.19-9.49 and 1.57-2.40,respectively,showing good synergism. Conclusion After Culex pipiens pallens yields resistance to propoxur,the mixtures of carbamate with synergists to control the mosquito may provide better efficacy and be worth extensive use.