INSECTICIDAL ACTIVITIES OF ESSENTIAL OILS EXTRACTED FROM THREE SPECIES OF POACEAE ON ANOPHELES GAMBIAE SPP,MAJOR VECTOR OF MALARIA

Abstract

In this paper, the insecticidal activities on Anopheles gambiae spp of the essential oils (EO) extracted from the dry leaves of some species collected in Benin were studied. The essential oil yields are 2.8, 1.7 and 1.4% respectively for Cymbopogon schoanenthus (L.) Spreng (CS), Cymbopogon citratus (CD) Stapf. (CC) and Cymbopogon giganteus (Hochst.) Chiov (CG). The GC/MS analysis showed that the EO of CS had a larger proportion in oxygenated monoterpenes (86.3%) whereas those of the sheets of CC and CG are relatively close proportions (85.5% and 82.7% respectively) with. The piperitone (68.5%), d-2-carene (11.5%), and a-eudesmol (4.6%) are the major components of the EO of CS while trans para-mentha-1(7),8-dien-2-ol (31.9%), trans para-mentha-2,8- dien-1-ol (19.6%), cis para-mentha-2,8-dien-1-ol (7.2%), trans piperitol (6.3%) and limonene (6.3%) prevailed in the EO of CG. The EO of CC revealed a rich composition in geranial (41.3%), neral (33%), myrcene (10.4%), and geraniol (6.6%). The biological tests have shown that these three EO induced 100% mortality of Anopheles gambiae to 1.1, 586.58 and 1549 μg·cm-2 respectively for CC, CS and CG. These effects are also illustrated by weak lethal concentration for 50% anopheles population (CC: 0.306; CS: 152.453 and CG: 568.327 μg·cm-2) in the same order of reactivity. The EO of CC appeared most active on two stocks (sensitive and resistant) of Anopheles gambiae.