Aeollanthus Pubescens Benth Leaf Essential Oil: Its Chemical Composition and the Insecticidal Activity Against the Malaria Vector Anopheles Gambiae (Diptera: Culicidae)

Abstract

Background: The use of synthetic insecticides is responsible for many cases of resistance in insects. Therefore, the use of natural molecules of ecological interest with insecticidal properties turns out to be an alternative approach to the use of synthetic insecticides. This study aims at investigating the larvicidal, adulticidal activity and the chemical composition of the essential oil of Aeollanthus pubescens Benth on the major malaria vector Anopheles gambiae.The leaves of Aeollanthus pubescens were collected in the South of the Republic of Benin.Methods: Three reference strains of Anopheles gambiae s.s. such as Kisumu, Kiskdr and Acerkis were used. The standard WHO guideline for larvicides evaluation was used and the chemical composition of the essential oil was analysed by gas chromatography coupled to mass spectrometry. Adult mosquitoes were exposed to the fragment nets coated with the essential oil for 3 min. Probit regression analysis was used for LC50 , LC95 , KDT50 , and KDT95 calculations. The difference between the mortality‐dose regressions for the different strains was analysed using the likelihood ratio test (LRT). The Log-rank test was performed to evaluate the difference in survival between the strains.Results: Fourteen components were identified representing 98.31% of the total of oil. The major components were carvacrol (51.06 %), thymyle acetate (14.01 %) and ɣ-terpinene (10.60 %). The essential oil has remarkable larvicidal properties with LC50 of 29.57, 22.95, and 28.37 ppm respectively on Kisumu, Acerkis and Kiskdr strains. With the fragment net treated at 165 µg/cm2, the KDT50 of both Acerkis (1.71 s, p < 0.001) and Kiskdr (2.67 s, p < 0.001) individuals were significantly lower than that of Kisumu (3.77 s). The lifespan of the three mosquito strains decreased respectively to one day for Kisumu (p < 0.001), two days for Acerkis (p < 0.001) and three days for Kiskdr (p < 0.001) compared to their control.Conclusion: Our findings show that the Aeollanthus pubescens essential oil is an efficient larvicide and adulticide against malaria vector Anopheles gambiae. This bioinsecticidal activity is a promising discovery for the control of the resistant malaria-transmitting vectors.