Mosquito larvicidal activity of essential oils of Cymbopogon citratus and Thymus vulgaris grown in Cameroon

The chemical composition and the larvicidal activity of the essential oils obtained by hydrodistillation of fresh leaves from Cymbopogon citratus and Thymus vulgaris growing in Cameroon were investigated. The yields of extraction indicate that leaves of Thymus vulgaris were richer (0.95%) in essential oil than those of Cymbopogon citratus (0.67%). By means of GC and GC/MS, the main compounds were found to be for Cymbopogon citratus : geraniol (31.95%), geranial (29.25%), sabinene acetate (15.57%) and myrcene (14.0%); and for Thymus vulgaris : thymol (40.11%), β-phellandrene (23.39%) and γ-terpene (15.15%). Biological testing revealed that both essential oils possess remarkable larvicidal properties as they could induce 100% mortality in the larveae of Anopheles gambiae at the concentration of 100 ppm for Cymbopogon citratus and at 200 ppm for Thymus vulgaris . The essential oil from C. citratus was found to be most toxic to the larvae.