Efficacy and persistence of essential oil of Monodora myristica against Anopheles gambiae, the main vector of malaria in sub-Saharan Africa

Abstract

Background: Monodora myristica known as calabash or nutmeg, is a tree of the Annonaceae family whose seeds are mainly used as a spice. The control of malaria is still a challenge partly due to mosquito resistance to conventional insecticides. The present work aimed to evaluate the insecticidal effect of the essential oil of M. myristica seeds to enlarge the list of local plants that can be used as insecticides. Methods: Essential oil was extracted by hydrodistillation using the Clevenger apparatus, then analyzed by gas chromatography to determine the chemical composition. using absolute alcohol, the essential oil was solubilized to obtain the stock solution which was used to prepare concentrations ranging from 10 to 250 ppm. Larvicide and adulticide tests were carried out with Anopheles gambiae larvae and females. The persistence of the M. myristica’s essential oil was determined by introducing the larvae into the prepared concentrations at regular time intervals and exposing them to the open air for 28 days. Results: The essential oil of M. myristica contained 20 chemical compounds and the major was the -phellandrene (35.20%). This essential oil-induced total mortality of A. gambiae larvae at all the concentrations after 24 h with concentration-dependent and larval age-dependent efficacy. In females, total mortality was recorded at 250 ppm and the LC95 was 168.47 ppm. The essential oil of M. myristica is still toxic towards A. gambiae after 21 days at the concentration of 150 ppm. Conclusion: These results led us to conclude that the essential oil of M. myristica could be a very good larvicide for vector control campaigns. Keywords: Monodora myristica; malaria; insecticide; plant; larvae; adults