Chemical composition and residue activities of Ocimum canum Sims and Ocimum basilicum L essential oils on adult female Anopheles funestus ss

Abstract

1 SUMMARY Essential oils obtained by hydrodistillation of the leaves of Ocimum canum (Camphor basil) and Ocimum basilicum (Sweet basil) were analyzed and their residual activity on adult Anopheles funestus ss determined. The extraction yields showed that the leaves of Ocimum canum are four times richer in essential oil (0.44%) than those of Ocimum basilicum (0.11%). Analysis by (GC) and (GC / MS) revealed that these oils are monoterpenic (83.4 to 92.4%). The oxygenated monoterpenes are predominant in the essential oil of Ocimum canum (63, 3%), while the monoterpene hydrocarbons are mainly in essential oil of Ocimum basilicum (56.2%). The major components identified in essential oil of O. canum are linalool (53.8%) and limonene (22.2%). The essential oil of O. basilicum is distinguished by the predominance of compounds such as linalool (18.9%), limonene (30.9%) and B-phellandrene (15.3%). Bioassay tests done by the World Health Organization standard protocol revealed that these essential oils have remarkable adulticidal properties on An. funestus ss. The essential oil of O. canum (LC50 = 45.61 ppm, one hour after exposure piece of nets to product) is the most efficient, followed by the essential oil of O. basilicum (LC50 = 84ppm). Besides, these studies have shown that the effectiveness of these species decreases significantly with time (LC50 for O. canum = 45.61, 62.53, 311.23 respectively one hour, five days and 10 days after exposure piece of nets to the product. LC50 for O. basilicum = 84; 171.7, 397respectively one hour, 5 days and 10 days after exposure piece of nets to the product). This result explains the low residue activity of these species on adult females of An. funestus . This low residue would be the fact of the highly volatile molecules of these species, and allows guiding insecticidal use of these essential oils in the form of aerosol bombs.