Objective: To investigate the seasonal Aedes population fluctuation and the resistance of Aedes populations to common insecticides in Jiangsu Province in 2020, so as to provide insights into vector-borne infectious diseases control.
Methods: One village was randomly sampled from each of Xinbei District of Changzhou City and Zhangjiagang County of Suzhou City in southern Jiangsu Province, Hai'an County of Nantong City and Yandu District of Yancheng City in Central Jiangsu Province, and Suining County of Xuzhou City and Sihong County of Suqian City in northern Jiangsu Province during the period between May and October, 2020. A small ponding container was sampled, and larval Aedes mosquitoes were collected using straws once each in early and late stages of each month. All larvae were bred in laboratory to adults for population identification. In addition, larval breeding were observed in all small ponding containers in and out of 30 households that were randomly sampled from six surveillance sites, and the larval mosquito density was estimated using Breteau index. Larval A. albopictus mosquitoes were sampled around Cuiyuan New Village in Jintan District of Changzhou City, and bred in laboratory to the first offspring generation, and the susceptibility of adult female mosquitoes to deltamethrin, lambda-cyhalothrin, malathion, and propoxur was tested using the filter-paper bioassay recommended by WHO.
Results: A total of 1 165 larval Aedes mosquitoes were captured from small ponding containers in six surveillance sites of Jiangsu Province in 2020, and all were identified as A. albopictus following eclosion. The largest number of Aedes larvae captured was found in July. A total of 1 152 households were investigated in six surveillance sites, and the mean Breteau indexes were 9.58, 13.20, 13.71, 13.20, 12.18 and 5.58 from May to October, respectively, while a high Aedes transmission risk was seen in Xinbei District of Changzhou City, with a higher Breteau index than in Suining (H = 23.667, Padjusted = 0.001) and Sihong (H = 22.500, Padjusted = 0.003) counties. The field-captured A. albopictus from Cuiyuan New Village in Jintan District of Changzhou City remained sensitive to malathion, but was resistant to propoxur, and developed high-level resistance to deltamethrin and lambda-cyhalothrin.
Conclusions: A. albopictus was present in southern, central and northern Jiangsu Province in 2020, and the larval density peaked in July. A. albopictus captured from Cuiyuan New Village in Jintan District of Changzhou City has developed high-level resistance to pyrethroid pesticides.
［摘要］ 目的 了解2020年江苏省伊蚊种群密度季节消长及对常用杀虫剂的抗药性, 为虫媒传染病防治提供依据。方法 2020年5—10月, 在江苏省南部常州市新北区和苏州市张家港市、中部南通市海安市和盐城市盐都区、北部徐州市 睢宁县和宿迁市泗洪县各选取1个自然村作为监测点, 在6个监测点各选1处定点小型积水容器, 每月上、下旬分别采用 吸管采集伊蚊幼虫1次。所采集幼虫在实验室内饲养至成蚊后进行种群鉴定。此外, 在6个监测点各选择30户居民家 庭, 检查室内外所有小型积水容器幼虫孳生情况, 并采用布雷图指数 (BI) 法计算幼虫密度。在常州市金坛区翠园新村周 围采集白纹伊蚊幼虫, 在实验室饲养至子1代, 采用成蚊接触筒强迫接触法测定雌性成蚊对溴氰菊酯、高效氯氰菊酯、马 拉硫磷、残杀威等4种常用杀虫剂的敏感性。结果 2020年在江苏省6个监测点定点小型积水容器内共捕获伊蚊幼虫 1 165条, 羽化后经鉴定均为白纹伊蚊, 7月捕获伊蚊幼虫数量最多。在6个监测点累计调查1 152户居民家庭, 5—10月 伊蚊幼虫平均BI值分别为9.58、13.20、13.71、13.20、12.18和5.58; 常州市新北区伊蚊传播风险较高, 其BI值高于睢宁县 (H = 23.667, P校正= 0.001) 和泗洪县 (H = 22.500, P校正= 0.003) 。常州市金坛区翠园新村周围现场白纹伊蚊对马拉硫磷 仍敏感, 但对残杀威已产生抗药性, 且对溴氰菊酯和高效氯氰菊酯抗性等级均为高度抗性。结论 2020年江苏省南部、中部、北部均存在白纹伊蚊, 7月为其幼虫密度高峰。常州市金坛区翠园新村周围白纹伊蚊已对拟除虫菊酯类产生高度抗性。.
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