Oregano Essential Oil as Potential Mosquito Larvicides

Abstract

Background: In view of residue problems in the environment and the development of insectresistance to synthetic insecticides like DDT and other chlorinatedhydrocarbons, the recent trend is to explore plants to obtainextractsthat are safe for non-target animals and do not pose any residue problem but are still able to suppresspest populations.Many studies on plant extracts against mosquito have been conducted around the world, and their larvicidal, pupicidal, adult emergence inhibition and repellent activities have been reported. Materials and Methods: In the presentstudy, the objective was to assess the chemical composition of the essential oilobtained by hydrodistillation of dry leavesfrom Origanumvulgare by GC-FID and GC/MS analyses. The essential oilwastestedatdifferent concentrations rangingbetween6.25 and 50 ppm on newlymoltedfourth-instar larvaeof Culex pipiens, mostabundant mosquito species in Tebessa area (East-Algeria) under standard laboratory conditions according to the World HealthOrganizationrecommendations. Results: The essential oilyieldcalculated from the dry matter of the aerial part of the plantwas 1.71 %. The GC-MS analyzes revealed twenty-five compounds in essential oils of O. vulgare. The major chemical components identified was carvacrol(77.63%) (Phenolicmonoterpene), followed by γ-terpinene (6.79%) and cymene (5.41%), respectively. Bioassay test revealedthatthis essential oilwasfound to exhibit a larvicidalactivitywith dose-responserelationship. Conclusion: The relationship between the chemical composition and biologicalactivity of essential oil of O. vulgare is confirmed by the above-mentioned results. Therefore, the potential for exploitingthis essential oil, such as bioinsecticide for vector control, canbetakenintoaccount.