Chemical composition and insecticidal activity of Aeollanthus pubescens Benth leaf essential oil on the malaria vector Anopheles gambiae (Diptera: Culicidae)

Abstract

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 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. Three reference strains of Anopheles gambiae s.s. such as Kisumu, Kiskdr and Acerkis were used. The chemical composition of the essential oil was analysed by gas chromatography coupled to mass spectrometry. Larvae were exposed to the essential oil extract for 24 h. Adult mosquitoes were exposed to the fragment nets coated with the essential oil for 3 min. Larval mortality and adult survivorship were monitored.Fourteen components were identified representing 98.31% of the total of oil. The major components were carvacrol (51.06 %), thymyle acetate (14.01 %) and γ-terpinene (10.60 %). The essential oil has remarkable larvicidal properties with LC50 of 29.26, 22.65, 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.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.