LARVICIDAL ACTIVITY OF ESSENTIAL OILS OF THYMUS VULGARIS AND ORIGANUM MAJORANA (LAMIACEAE) AGAINST OF THE MALARIA VECTOR ANOPHELES LABRANCHIAE (DIPTERA: CULICIDAE)

Objective: We evaluated the properties of larvicidal activity of essential oils of Thymus vulgaris and Origanum majorana family of Lamiaceae collected at Taounate province in the North East of Morocco, against the larvae of the malaria vector Anopheles labranchiae (Diptera: Culicidae). There are no published data on the effect of these plants on this mosquito, formerly responsible for indigenous malaria. Methods: Biological tests were realized according to a methodology inspired from standard WHO protocol, slightly modified, using the Ethanol as a solvent instead of DMSO. The method consists of making expose the larvae of stages 3 and 4 of the species An. labranchiae to the various concentrations of essential oils. After 24 h of contact, we counted living and dead larvae. Results: The mortality percentages were determined after 24 h. Lethal Concentrations (LC 50 and LC 90 ) were calculated and measured. They were respectively of the order of 351.63 µg/ml and 621.34 µg/ml for the essential oil of Thymus vulgari ; whereas Origanum majorana were found of the order of LC 50 = 107.13 µg/ml and LC 90 = 365.9 µg/ml. Conclusion: The results could be useful and interesting for the new application in the production of biocides against the larvae of Anopheles. Also, this information will be needed for the control program and for improving the vector control practices. Keywords: Thymus vulgaris , Origanum majorana , Larvicidal activity, Anopheles labranchiae , Biological tests, North Eastern Morocco