The Phytochemical Components of Leucas Martinicensis that Cause Repellence of Adult Mosquito

The research was conducted between May, 2009 and January, 2010 on the “The Phytochemical component of Leucas martinicensis that cause repellence of adult mosquitoes”. The skin repellency of L. martinicensis leaf extract was determined by noting number of bites by adult mosquito in varying concentrations of 2.5%, 5.0%, 10.0% and 20.0% and at various time interval of 5, 10, 15, 20, 30, 45 and 60 minutes respectively for all concentration. The extract was fractionated using methanol and chloroform and its skin repellency was also noted, at exposure of skin in 1 in 5 minutes. Observation shows that low repellence was observed with 1.00 and 0.67 means bites over 5 and 45 minutes respectively at 2.5% concentration of the extract. The highest repellency was observed to be 0.00 mean bite over 5 and 60 minutes exposure at 20.0% concentration, however, bite by culex adult mosquitoes was highest in the control with 1.25 bites. The fractions of methanol and chloroform gave no significant difference with the control experiment. The phytochemical screening of the leaf extract revealed that presence of flavonoids, alkanoids and volatile oil might be responsible for repelling the adult culex mosquitoes, this research work may serve as a baseline for more investigation on the mode of application and action of the active ingredient.