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目的了解陕西省流行性乙型脑炎(乙脑)高发区三带喙库蚊对常用杀虫剂的抗药性水平。方法采用人工小时法调查蚊虫密度;采用区分剂量法测定5种杀虫剂对三带喙库蚊幼虫的24h死亡率;采用半数致死量法测定8种杀虫剂对三带喙库蚊幼虫的LC50。结果乙脑高发区养殖场所三带喙库蚊平均密度为194.91只/人工小时;区分剂量法测定敌敌畏、溴氰菊酯对南郑、汉阴、汉滨、平利4个县(区)三带喙库蚊幼虫的24h死亡率分别为1.84%～13.65%和10.86%～31.25%;半数致死量法测定同一种杀虫剂对不同地区三带喙库蚊的LC50相差1.27～8.00倍。结论三带喙库蚊为陕西省乙脑高发区养殖场所的优势蚊种。除平利、南郑2个县三带喙库蚊对DDT敏感,汉滨、南郑2个县三带喙库蚊对氯氰菊酯敏感外,4个调查点的三带喙库蚊对所测试的其他杀虫剂均不同程度地产生了抗药性,其中对敌敌畏和溴氰菊酯的抗药性均达到高抗水平,对氯菊酯的抗药性达到中抗以上水平。化学防制中宜采取禁用、轮用和混用药物等措施以延缓抗药性的发展。
Objective To understand the resistance level of Culex tritaeniorhynchus to commonly used insecticides in high incidence area of Japanese encephalitis (JE) in Shaanxi Province. Methods The artificial insects were used to investigate the density of mosquitoes. The discrimination of 5 insecticides against the larvae of Culex trituberclivora was carried out using the method of discriminating dose, and the mortality of Culex tritaeniorhynchus larvae LC50. Results The average density of Culex tritaeniorhynchus in farms in high-incidence area of JE was 194.91 / man-hour. Dose-dose method was used to determine the effect of dichlorvos and deltamethrin on four counties (districts) in Nanzheng, Hanyin, Hanbin and Pingli The 24h mortality of Culex tritaeniorhynchus larvae was 1.84% -13.65% and 10.86% -31.25%, respectively. The LC50 of the same pesticide against Culex tritaeniorhynchus from different areas was 1.27-8.00 times as high as that of the control. Conclusion Culex tritaeniorhynchus is the dominant mosquito species in breeding areas with high incidence of Japanese encephalitis in Shaanxi Province. In addition to Pingliang, the two counties of Nanzheng were sensitive to DDT, Culex tritaeniorhynchus were sensitive to cypermethrin in two counties of Hanbin and Nanzheng, Other insecticides all developed resistance to varying degrees, among which the resistance to dichlorvos and deltamethrin reached high levels, and the resistance to permethrin reached above the level of resistance. Chemical control should be banned, rounds and mixed with drugs and other measures to delay the development of drug resistance.