Abstract: Objective To investigate the resistance level of Culex pipiens pallens to commonly used insecticides in Tianjin,China, to analyze its changing trend, and to provide scientific and rational guidance for the chemical control. Methods The larvae of Cx. pipiens pallens were collected in 2013, 2016, and 2019. The first generation was fed in the laboratory. The late third-instar or early forth-instar larvae were then selected as test subjects, and the larval dipping method was used to measure their insecticide resistance. Results In 2013, 2016, and 2019, the Cx. pipiens pallens at various surveillance sites in Tianjin all showed varying degrees of resistance to beta-cypermethrin, deltamethrin, and temephos. In different years, Cx. pipiens pallens at various surveillance sites all showed medium or low resistance to beta-cypermethrin; Cx. pipiens pallens in Hebei district had the highest resistance in the whole city, with a resistance ratio of 20.94. Culex pipiens pallens showed high, medium, or low resistance to deltamethrin and temephos; Cx. pipiens pallens in Hedong district had the highest resistance to deltamethrin, with a resistance ratio of 69.78; Cx. pipiens pallens in Beichen district had the highest resistance to temephos, with a resistance ratio of 57.14. The resistance levels of Cx. pipiens pallens to the three insecticides showed overall upward trends from 2013 to 2016, and then the number of districts resistant to beta-cypermethrin and temephos decreased from 7 in 2016 to 5 and 6 in 2019, respectively, while the number of districts resistant to deltamethrin did not change. Conclusion In Tianjin, Cx. pipiens pallens has developed resistance to all of beta-cypermethrin, deltamethrin,and temephos. It is recommended that insecticides should be used scientifically and reasonably based on the surveillance results of insecticide resistance. At the same time, a rotation and mixed use of insecticides should be adopted to delay the development of resistance.

Key words: Culex pipiens pallens, Insecticide resistance, Resistance trend

摘要： 目的 了解天津市淡色库蚊对常用杀虫剂的抗性水平，分析其变化趋势，为化学防治提供科学合理的用药指导。方法 于2013、2016和2019年采集淡色库幼蚊，实验室饲养1代，选择3龄末4龄初的幼蚊为测试对象，采用幼虫浸渍法进行抗性测定。结果 2013、2016和2019年天津市不同监测点淡色库蚊对高效氯氰菊酯、溴氰菊酯、双硫磷均有不同程度的抗性。不同年份所有监测点淡色库蚊对高效氯氰菊酯均为中、低抗性水平，河北区为全市最高抗性，抗性倍数为20.94倍；对溴氰菊酯和双硫磷均存在高、中、低抗性水平，河东区对溴氰菊酯的抗性最高，抗性倍数高达69.78倍；北辰区对双硫磷的抗性最高，抗性倍数达57.14倍。2013－2016年淡色库蚊对3种杀虫剂的抗性水平整体呈现上升趋势，2016－2019年高效氯氰菊酯和双硫磷抗性地区数量有所下降，分别由2016年的7个下降至2019年的5和6个，而溴氰菊酯抗性地区数量未发生变化。结论 天津市淡色库蚊对高效氯氰菊酯、溴氰菊酯、双硫磷均产生抗性，建议根据抗药性监测结果，科学合理使用杀虫剂，同时注意杀虫剂的混用与轮用，延缓抗性产生。

关键词: 淡色库蚊, 抗药性, 抗性趋势