Aquatain® Mosquito Formulation (AMF) for the control of immature Anopheles gambiae sensu stricto and Anopheles arabiensis: dose-responses, persistence and sub-lethal effects

Abstract

BackgroundPersistent monomolecular surface films could benefit larval source management for malaria control by reducing programme costs and managing insecticide resistance. This study evaluated the efficacy of the silicone-based surface film, Aquatain® Mosquito Formulation (AMF), for the control of the Afrotropical malaria vectors, Anopheles gambiae sensu stricto and Anopheles arabiensis in laboratory dose–response assays and standardized field tests.MethodsTests were carried out following guidelines made by the World Health Organization Pesticide Evaluation Scheme (WHOPES). Sub-lethal effects of AMF were evaluated by measuring egg-laying and hatching of eggs laid by female An. gambiae s.s. that emerged from habitats treated with a dose that resulted in 50% larval mortality in laboratory tests.ResultsBoth vector species were highly susceptible to AMF. The estimated lethal doses to cause complete larval mortality in dose–response tests in the laboratory were 1.23 (95% confidence interval (CI) 0.99-1.59) ml/m2 for An. gambiae s.s. and 1.35 (95% CI 1.09-1.75) ml/m2 for An. arabiensis. Standardized field tests showed that a single dose of AMF at 1 ml/m2 inhibited emergence by 85% (95% CI 82-88%) for six weeks. Females exposed as larvae to a sub-lethal dose of AMF were 2.2 times less likely (Odds ratio (OR) 0.45, 95% CI 0.26-0.78) to lay eggs compared to those from untreated ponds. However, exposure to sub-lethal doses neither affected the number of eggs laid by females nor the proportion hatching.ConclusionAMF provided high levels of larval control for a minimum of six weeks, with sub-lethal doses reducing the ability of female mosquitoes to lay eggs. The application of AMF provides a promising novel strategy for larval control interventions against malaria vectors in Africa. Further field studies in different eco-epidemiological settings are justified to determine the persistence of AMF film for mosquito vector control and its potential for inclusion in integrated vector management programmes.

Aquatain AMF efficacy on juvenile mosquito stages in control of Culex pipiens complex and Aedes albopictus

“…According to our findings in laboratory and semifield experiments, AMF significantly suppressed mosquitoes in artificial water recipients, frequently inhabited by C. pipiens and A. albopictus. AMF was shown to have multistage effects on A. albopictus and C. pipiens which corroborates with earlier findings (Bukhari & Knols, 2009;Webb & Russell, 2009Bukhari et al, 2011;Wang et al, 2013;Mbare et al, 2014;Sukkanon et al, 2016). Ngrenngarmlert et al (2016) found no adverse effects of Aquatain on fish and plants.…”

Semi-field and field studies on the efficacy of monomolecular surface film (Agnique®) against immature mosquitoes in the malarious areas of Iran

“…Recently, many studies have been done in order to evaluate the efficacy of MMF in different medically important species in several countries [17][18][19][20][21][22][23][24]. Efficacy of Agnique ® MMF was tested against immature stages of An.…”

“…By forming a uniform thin layer on the water surface, this biodegradable oil suffocates mosquito larvae and pupae, hardens adult's emergence, and prevents laying eggs in applied breeding places. Efficacy of these methods has been studied in several species of mosquitoes in different parts throughout the world [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24].…”

Mapping hotspots of malaria transmission from pre-existing hydrology, geology and geomorphology data in the pre-elimination context of Zanzibar, United Republic of Tanzania

“…It is becoming more apparent that if we are to achieve the ambitious goal of eliminating malaria, it will be necessary to complement current priority interventions for controlling adult mosquitoes that feed and rest indoors, such as long-lasting insecticide treated nets (LLINs) and indoor residual house spraying (IRS) by targeting vector mosquitoes at aquatic habitats where they are most vulnerable. This can be achieved through larval source management techniques such as environmental management or larviciding [ 1 - 8 ].…”