Insecticidal activity of <i>Artemisia annua L</i>. (CBGE/CHNA/09/LTNGS/G) ethanolic leaf and seed extracts on <i>Anopheles gambiae</i>

Abstract

The dry leaves (500g) and dry seeds (500g) of Artemisia annua L. were separately extracted with 2 litres of ethanol for a period of 48 hrs at room temperature (25^oC). The phytochemical constituents of the plant were determined. The extracts (leaves and seeds) were tested singly and in combinations for their insecticidal activities at different concentrations (1.0mg/litre, 2.0mg/litre, 4.0 mg/litre and 5.0mg/litre) on Anopheles gambiae 4^th instar larvae, pupae and adult females. The effects of the smoke from burning dry leaves of A. annua on A. gambiae (larvae, pupae and female adults) were also determined. The plant was found to contain alkaloids, flavonoids, glycosides, phenols, resins and tannins. Artemisinin, a secondary metabolite which is essential for the production of antimalaria drugs was extracted from the plant. The plant was also found to contain oil (essential oil). The extracts were found to have lethal effects on the larvae, pupae and adult females of A. gambiae. A combination of the leaf and seed extracts was found to be more lethal than the singler effects of either of the extracts. The smoke from the burning dry leaves of the plant was found to have lethal and repellent effects on the mosquitoes. The volatile nature of the constituents of the leaf and seed extracts may have been responsible for their insecticidal actions. The implications of the results obtained have been discussed.

Keywords: Artemia annua L., Anopheles gambiae, ethanolic, mosquitoes, extracts, anti-malaria