SHORT COMMUNICATION Larvicidal Activity of the Essential Oil from Lippia sidoides Cham. against Aedes aegypti Linn.

The aim of this work was to study the larvicidal activity of Lippia sidoides essential oil against Aedes aegypti larvae. The essential oil and its hydrolate (saturated solution of essential oil in water) were obtained by vapor extraction and their chemical composition determined by GL-chromatography coupled to mass spectroscopy. Bio-assays were run with the essential oil, pure and diluted hydrolate and with their main constituents thymol and carvacrol. The results obtained showed that L. sidoides essential oil and its hydrolate have larvicidal action against the mosquito A. aegypti, causing an almost instantaneous mortality. Thymol, an alkylated phenol derivative and one of the major components of L. sidoides essential oil, was identified as the active principle responsible for the larvicidal action, causing 100 % larval mortality at the lowest tested concentration of 0.017 % (w/v). These results suggest that the essential oil of L. sidoides is promising as larvicide against A. aegypti and could be useful in the search of newer, more selective, and biodegradable larvicidal natural compounds to be used in official combat programs and at home. Key words: Lippia sidoides- larvicidal activity- thymol Mosquitoes are responsible for more diseases than any other group of arthropods (Cepleanu 1993). The mos-quito Aedes aegypti acts as a vector for an arbovirus re