Measuring repellence and mortality effects of clove and cinnamon essential oils impregnated nets against Anopheles gambiae senso stricto using tunnel test

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BackgroundThe control of malaria vectors in Tanzania focuses on the use of synthetic insecticides, which are either impregnated into mosquito nets or used in residual insecticide sprays (IRS). However, one of the major limitations of using insecticides is the development of resistance among the malaria vectors. Thus, there is a need to assess the usefulness of the available natural products such as clove and cinnamon essential oils and determine their repellence and mortality effects against the major malaria vectors. In that context, the current study assessed the chemical composition of clove and cinnamon and the effect of cinnamon and clove essential oils treated nets in causing mortality in the Anopheles gambiae population. MethodA tunnel chamber was used to evaluate the blood-feeding inhibition (repellence) and mortality due to the essential oils impregnated polystyrene nets against Yorkool, a standard Long Lasting Insecticides Nets (LLINs). The unfed 2250 females of An. gambiae s.s. aged 3 days old were used. Each replicate of the Tunnel Chamber experiment used 50 mosquitoes for each concentration(45,55,65 ml/m2) replicated thrice. ResultsThe chemical composition of clove and cinnamon essential oils showed one common chemical, Eugenol (4-alil-2-metoxyphenol), at the highest composition. The findings of the evaluated essential oils showed high mortality and repellence activities against adults of An. gambiae s.s. though they had different active chemical ingredients. The mortality effect was 54%, 70.7% and 77.3% for clove, while for cinnamon it was 89.3%, 88.7% and 89.2% for concentrations of 45 ml/m2, 55 ml/m2 and 65 ml/m2 respectively. ConclusionThe findings of this study have shown that clove and cinnamon essential oils exhibit repellence and toxicity effects against An. gambiae and may be considered as a potential tool for controlling mosquito-human contact.