相邻场所白纹伊蚊抗药性差异研究

Study on insecticide resistance difference of Aedes albopictus between adjacent sites

目的通过对比相邻场所白纹伊蚊的抗药性差异,了解抗药性的发生范围,探寻合理的抗药性监测采集点的选择方法。方法 2018年8-10月在深圳市某地2 km范围内选择6个近直线分布的采集点采集试虫,6个采集点环境分别为2个居民小区,1个单位中的2个地点,1个近山工棚,1个野外林区;使用幼虫浸渍法的敏感基线法开展抗药性实验;利用半数致死浓度(LC50)的95%可信区间(95%CI)是否重合判断不同采集点抗药性差异有无统计学意义。结果不同采集点间白纹伊蚊抗药性水平差别较大,高效氯氰菊酯抗性倍数范围为1.68~86.20倍,高抗、低抗和敏感的监测点分别有2、1和3个;氯菊酯抗性倍数范围为1.68~58.99倍,高抗、中抗和敏感的监测分别有1、3和2个;倍硫磷抗性倍数范围为1.24~6.58倍,4个监测点低抗,2个敏感。除氯菊酯的C、D两点,倍硫磷的D、E两点外,其余同种药物在相邻2个采集点LC50差异均有统计学意义(LC50的95%CI无重叠)。结论白纹伊蚊抗药性可以在很小范围产生,1个具体场所的抗药性监测结果不能代表周边场所的抗药性水平;在1个较大区域进行抗药性监测,需要选择尽可能多的采集点开展实验,以准确反映该区域的抗药性水平。

Objective To investigate the area with the development of insecticide resistance and explore a method for selecting reasonable sampling sites for resistance monitoring by comparing the insecticide resistance of Aedes albopictus between adjacent sites. Methods From August to October 2018, mosquitoes were collected from six sampling sites which were distributed in an approximately straight line within 2 km of a place in Shenzhen, Guangdong province, China. The six sampling sites were situated in two residential areas, two locations of an institution, a work shed near the hill, and a forest,respectively. Insecticide resistance was determined based on baseline sensitivity by the larval dipping method. The resistance was compared between different sampling sites, and the statistical significance for the difference was determined based on whether the 95% confidence intervals(CI) for median lethal concentrations(LC50) overlapped. Results There were great distinctions in the resistance levels of Ae. albopictus between different sampling sites. The resistance ratios to beta-cypermethrin ranged from 1.68 to 86.20, and there were two, one, and three sampling sites showing high resistance,low resistance, and susceptibility, respectively. The resistance ratios to permethrin ranged from 1.68 to 58.99, and there were one, three and two sampling sites showing high resistance, moderate resistance, and susceptibility, respectively. The resistance ratios to fenthion ranged from 1.24 to 6.58, and there were four and two sampling sites showing low resistance and susceptibility, respectively. There were significant differences in LC50(i.e., no overlap of the 95%CI for LC50) of any of the insecticides between two adjacent sampling sites, except between C and D sites for permethrin and between D and E sites for fenthion. Conclusion The insecticide resistance of Ae. albopictus can develop within a small area. The resistance status of a specific site can not represent that of surrounding sites. When monitoring insecticide resistance in a large area, it is necessary to select as many sampling sites as possible, so as to accurately reflect the level of insecticide resistance in the area.