Gimnig John E, Ombok Maurice, Bayoh Nabie, Mathias Derrick, Ochomo Eric, Jany William, Walker Edward D
Centers for Disease Control and Prevention, Division of Parasitic Diseases and Malaria, Atlanta, GA, USA.
Kenya Medical Research Institute, Centre for Global Health Research, Kisumu, Kenya.
Malar J. 2020 Nov 26;19(1):436. doi: 10.1186/s12936-020-03507-y.
Larval source management is recommended as a supplementary vector control measure for the prevention of malaria. Among the concerns related to larviciding is the feasibility of implementation in tropical areas with large numbers of habitats and the need for frequent application. Formulated products of spinosad that are designed to be effective for several weeks may mitigate some of these concerns.
In a semi-field study, three formulations of spinosad (emulsifiable concentrate, extended release granules and tablet formulations) were tested in naturalistic habitats in comparison to an untreated control. Cohorts of third instar Anopheles gambiae (Diptera: Culicidae) were introduced into the habitats in screened cages every week up to four weeks after application and monitored for survivorship over three days. A small-scale field trial was then conducted in two villages. Two of the spinosad formulations were applied in one village over the course of 18 months. Immature mosquito populations were monitored with standard dippers in sentinel sites and adult populations were monitored by pyrethrum spray catches.
In the semi-field study, the efficacy of the emulsifiable concentrate of spinosad waned 1 week after treatment. Mortality in habitats treated with the extended release granular formulation of spinosad was initially high but declined gradually over 4 weeks while mortality in habitats treated with the dispersable tablet formulation was low immediately after treatment but rose to 100% through four weeks. In the field study, immature and adult Anopheles mosquito populations were significantly lower in the intervention village compared to the control village during the larviciding period. Numbers of collected mosquitoes were lower in the intervention village compared to the control village during the post-intervention period but the difference was not statistically significant.
The extended release granular formulation and the dispersible tablet formulations of spinosad are effective against larval Anopheles mosquitoes for up to four weeks and may be an effective tool as part of larval source management programmes for reducing adult mosquito density and malaria transmission.
推荐幼虫源管理作为预防疟疾的补充病媒控制措施。与杀幼虫剂相关的问题包括在栖息地众多的热带地区实施的可行性以及频繁应用的必要性。设计能在数周内保持有效的多杀菌素制剂可能会缓解其中一些问题。
在一项半野外研究中，将三种多杀菌素制剂（乳油、缓释颗粒剂和片剂）与未处理对照在自然栖息地中进行测试。在施用后长达四周的时间里，每周将一批冈比亚按蚊（双翅目：蚊科）三龄幼虫引入置于栖息地的纱笼中，并监测其三天的存活情况。然后在两个村庄进行了一项小规模田间试验。在18个月的时间里，在一个村庄施用了两种多杀菌素制剂。在哨兵点用标准水勺监测未成熟蚊虫种群，并用除虫菊酯喷雾捕捉法监测成虫种群。
在半野外研究中，多杀菌素乳油的药效在处理后1周减弱。用多杀菌素缓释颗粒剂处理的栖息地中的死亡率最初较高，但在4周内逐渐下降，而用可分散片剂处理的栖息地中的死亡率在处理后立即较低，但在四周内升至100%。在田间研究中，在杀幼虫剂施用期间，干预村庄的未成熟和成年按蚊种群明显低于对照村庄。在干预后期间，干预村庄捕获的蚊子数量低于对照村庄，但差异无统计学意义。
多杀菌素缓释颗粒剂和可分散片剂对按蚊幼虫有效长达四周，可能是作为幼虫源管理计划的一部分，用于降低成蚊密度和疟疾传播的有效工具。
