景洪市登革热媒介伊蚊对吡丙醚的敏感性及其作用特点

Resistance and mortality pattern of dengue vectors exposed to pyriproxyfen in Jinghong city,Yunnan province

目的测定景洪市登革热媒介埃及伊蚊和白纹伊蚊幼虫对吡丙醚的敏感性,并观察吡丙醚在不同剂量下蚊虫的死亡特点,为当地蚊虫控制及抗性治理提供依据。方法 2015年10-11月,在景洪市登革热暴发期间,采集媒介伊蚊幼虫,用世界卫生组织推荐的昆虫生长调节剂抗药性测定方法,计算吡丙醚对蚊虫的半数抑制剂量(IE50),并以实验室敏感品系为对照,获得抗性倍数;同时,通过逐日观察不同药剂浓度下试虫的死亡率和死亡虫态构成,来分析吡丙醚对两种伊蚊的毒杀作用特点。结果景洪市埃及伊蚊和白纹伊蚊种群幼虫对吡丙醚的IE50及其95%CI分别为0.024 47(0.022 09~0.027 07)和0.135 20(0.117 10~0.156 60)μg/L,分别是敏感品系的0.85和13.44倍;景洪市的白纹伊蚊比埃及伊蚊对吡丙醚的耐受力高5.53倍。3龄试虫在接触不同浓度的吡丙醚后,其死亡高峰均在第4~6天;敏感品系的埃及伊蚊和白纹伊蚊死亡高峰分别在第4~5天和第4天;景洪种群的埃及伊蚊和白纹伊蚊死亡高峰较宽,在第4~6天。低浓度药物作用下的死亡虫态以畸形成蚊与蛹在羽化中死亡为主;当抑制率>60%时,敏感品系开始持续出现蛹的死亡,且蛹的死亡比例随浓度增加而增大;景洪种群有波动。结论景洪市埃及伊蚊对吡丙醚敏感,因其是该地区登革热的主要传播媒介,且主要分布在市区,可以在市区推广使用;尽管白纹伊蚊幼虫产生了中度抗性,但可与其他杀虫剂配合使用,以延缓抗性发展。因此,吡丙醚可应用于当地蚊虫控制及抗性治理,但应定期开展蚊虫抗药性监测工作,及时了解其抗性发展动态。

Objective To test the resistance to pyriproxyfen in dengue vectors Aedes aegypti and Ae. albopictus and observe the mortality pattern of mosquitoes at various concentrations in Jinghong city, Yunnan province, so as to provide evidence for dengue vectors control and resistance management. Methods Aedes larvae were collected from Dengue epidemic areas in Jinghong from October to November, 2015. WHO recommended methods for insect growth regulators was carried out on the 3rd instar larvae collected. The resistance ratio （RR） was calculated by comparing half inhibition of emergence concentration （IEs0） of the tested wild population with the susceptible reference strain. Additionally, the mortality pattern of dengue vectors exposed to pyriproxyfen was analyzed by observing daily stage-specific mortality at various concentrations. Results The IE50s of Ae. aegypti and Ae. albopictus in Jinghong city were 0.024 47 （0.022 09-0.027 07） and 0.135 20 （0.117 10-0.156 60） μg/L. There was 13.44-fold resistance in Ae. albopictus and 0.85-fold resistance in Ae. aegypti to pyriproxyfen compared with the susceptible strains respectively. Aedes albopictus was also 5.53-fold more tolerant topyriproxyfen than Ae. aegypti in Jinghong city. For the dead individuals, most of them died at 4-6 d after exposure to pyriproxyfen, and the peak of death for susceptible Ae. aegypti and Ae. albopictus were at 4-5 d and 4 d respectively. A wider range of death peak was observed for Jinghong population of Ae. aegypti and Ae. albopictus, which was at 4-6 d. At low concentrations, most of the dead were deformed adults and mosquitoes not completely separated from the pupae. For the susceptible reference strain, dead pupae began to occur steadily when the mortality was over 60%, and the proportion increased as the concentration went up. However, the mortality of pupae was fluctuating in Jinghong population. Conclusion In Jinghong city, Ae. aegypti larvae was susceptible to pyriproxyfen. Considering this species is preferentially found in urban areas, pyriproxyfen is recommended to use in urban areas. Although Ae. albopictus larvae have developed moderate resistance to pyriproxyfen, this larvicide still can be used in ahernatery with other insecticides to delay the resistance development. It proves that pyriproxyfen is highly efficient for mosquito control and resistance management in Jinghong city. Periodic resistance monitoring must be conducted to learn the variations of resistance level timely.