陕西省流行性乙型脑炎高发区三带喙库蚊的抗药性研究

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。

Resistance of Culex tritaeniorhynchus to several traditional insecticides in high incidence areas of Japanese encephalitis in Shaanxi province

Objective To investigate the resistance of Culex tritaeniorhynchus to insecticides used frequently in high incidence areas of Japanese encephalitis in Shaanxi province. Methods The density of mosquitoes was calculated by labor hour method. Larva death rate of five insecticides and LC50 of eight insecticides were determined by distinguishing dosage method and median lethal dose method respectively. Results The average density of Cx.tritaeniorhynchus in breeding farm was 194.91/manhour. The mortality of mosquitoes in Nanzheng, Hanyin, Hanbin and Pingli county was 1.84%-13.65% and 10.86%-31.25 % after treatment by DDVP and dehamethrin for 24 h. Maximum LC50 of the same insecticide in different areas wasl.27-8.00 times of the minimum. Conclusion Cx.tritaeniorhynchus developed different resistance to tested insecticides in four investigation sites, except that it was susceptible to cypermethrin in Hanbin, Nanzheng county and to DDT in Pingli, Nanzheng county. Cx.tritaeniorhynchus populations had developed high resistance to DDVP and deltamethrin, moderate resistance to permethrin. Rotational or mixed use of insecticides with different action mechanisms should be adopted to postpone the development of insecticide resistance.