Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand.
Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, England, United Kingdom.
PLoS One. 2020 Apr 14;15(4):e0231251. doi: 10.1371/journal.pone.0231251. eCollection 2020.
Outdoor residual spraying is proposed for the control of exophilic mosquitoes. However, the residual effect of insecticide mists applied to outdoor resting habitats of mosquitoes is not well characterized. The objective of this study was to assess the longevity of the residual insecticidal effect of three pyrethroid formulations applied to outdoor vegetation against the Southeast Asian malaria vector Anopheles dirus. Lambda-cyhalothrin capsule suspension, deltamethrin emulsifiable concentrate and bifenthrin wettable powder were sprayed on dense bamboo bushes on the Thailand-Myanmar border during the dry season 2018. The duration and magnitude of the residual insecticidal effect were assessed weekly with a standard cone assay, using freshly collected insecticide-treated bamboo leaves and a laboratory-adapted colony of Anopheles dirus sensu stricto susceptible to pyrethroids. The experiment was repeated during the rainy season to assess the persistence of the lambda-cyhalothrin formulation after natural rains and artificial washings. During the dry season (cumulative rainfall = 28 mm in 111 days), mortality and knockdown (KD) rates were >80% for 60 days with bifenthrin and 90 days with lambda-cyhalothrin and deltamethrin. The 50% knockdown time (TKD50) was <15 min with lambda-cyhalothrin and deltamethrin, and <30 min with bifenthrin. During the rainy season (cumulative rainfall = 465 mm in 51 days), mortality and KD rates were >80% for 42 days and TKD50 was <15 min with lambda-cyhalothrin. Additional artificial washing of the testing material with 10L of tap water before performing the cone tests had no significant effect on the residual insecticidal effect of this formulation. Long-lasting residual insecticidal effect can be obtained when spraying pyrethroid insecticides on the outdoor resting habitats of malaria vectors.
户外滞留喷洒被提议用于控制嗜人按蚊。然而，应用于蚊子户外栖息场所的杀虫剂雾剂的残留效果尚未得到很好的描述。本研究的目的是评估三种拟除虫菊酯制剂应用于户外植被对东南亚疟疾传播媒介致倦库蚊的残留杀虫效果的持久性。2018 年旱季期间，在泰缅边境的茂密竹林上喷洒了氯氟氰菊酯胶囊悬浮剂、溴氰菊酯乳油和高效氯氟氰菊酯可湿性粉剂。每周使用标准锥形测定法评估残留杀虫效果的持续时间和强度，使用新鲜收集的经杀虫剂处理的竹叶和对拟除虫菊酯敏感的实验室适应的致倦库蚊种群进行测定。在雨季，重复进行实验以评估自然降雨和人工冲洗后氯氟氰菊酯制剂的持久性。在旱季（111 天内累计降雨量为 28 毫米），60 天时高效氯氟氰菊酯和氯氟氰菊酯的死亡率和击倒率（KD）超过 80%，90 天时溴氰菊酯的死亡率和 KD 超过 80%。氯氟氰菊酯和溴氰菊酯的 50%击倒时间（TKD50）<15 分钟，而高效氯氟氰菊酯的 TKD50<30 分钟。在雨季（51 天内累计降雨量为 465 毫米），42 天时氯氟氰菊酯的死亡率和 KD 超过 80%，TKD50<15 分钟。在进行锥形试验之前，用 10L 自来水对测试材料进行额外的人工冲洗，对该制剂的残留杀虫效果没有显著影响。当在疟疾传播媒介的户外栖息场所喷洒拟除虫菊酯杀虫剂时，可以获得持久的残留杀虫效果。
