Abstract
BackgroundLarviciding is a key strategy used in many vector control programmes around the world. Costs could be reduced if larvicides could be manufactured locally. The potential of natural products as larvicides against the main African malaria vector, Anopheles gambiae s.s was evaluated.MethodsTo assess the larvicidal efficacy of a neem (Azadirachta indica) oil formulation (azadirachtin content of 0.03% w/v) on An. gambiae s.s., larvae were exposed as third and fourth instars to a normal diet supplemented with the neem oil formulations in different concentrations. A control group of larvae was exposed to a corn oil formulation in similar concentrations.ResultsNeem oil had an LC50 value of 11 ppm after 8 days, which was nearly five times more toxic than the corn oil formulation. Adult emergence was inhibited by 50% at a concentration of 6 ppm. Significant reductions on growth indices and pupation, besides prolonged larval periods, were observed at neem oil concentrations above 8 ppm. The corn oil formulation, in contrast, produced no growth disruption within the tested range of concentrations.ConclusionNeem oil has good larvicidal properties for An. gambiae s.s. and suppresses successful adult emergence at very low concentrations. Considering the wide distribution and availability of this tree and its products along the East African coast, this may prove a readily available and cheap alternative to conventional larvicides.
Highlights
Larviciding is a key strategy used in many vector control programmes around the world
Malaria in sub-Saharan Africa can be controlled by attacking its prime vectors, notably Anopheles gambiae s.l
Mosquitoes The An. gambiae s.s. larvae used in this study were from a colony established in 2001 at the Thomas Odhiambo campus of the International Centre of Insect Physiology and Ecology (ICIPE), Mbita Point, western Kenya
Summary
Larviciding is a key strategy used in many vector control programmes around the world. Malaria in sub-Saharan Africa can be controlled by attacking its prime vectors, notably Anopheles gambiae s.l. Since the onset of mosquito control activities in the early 1900s, several challenges continue to hinder efforts to effectively control malaria. Since the onset of mosquito control activities in the early 1900s, several challenges continue to hinder efforts to effectively control malaria These include insecticide resistance, limited access to essential resources (human, capital, and equipment) that affect conventional use of control methods, and insect adaptation and altered behavioural traits, such as exophily and exophagy [1]. Use of larvicides, which dates back to as early as 1899, when Ronald Ross applied kerosene on anopheline larval breeding sites in Sierra Leone [2], is an approach with great potential for future malaria vector control [3]. It is worth emphasizing that larval control is not (page number not for citation purposes)
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