Submitted to: Asian Pacific Journal of Tropical Medicine
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 15, 2012
Publication Date: April 20, 2012
Citation: Kovendan, K., Murugan, K., Vincent, S., Barnard, D.R. 2012. Mosquito larvicidal properties of Orthisiphon thymiflorus (Roth) Sleesen. (Family: Labiatae) against mosquito vectors, Anopheles stephensi, Culex quinquefasciatus and Aedes aegypti (Diptera: Culicidae). Asian Pacific Journal of Clinical Nutrition. 5(4):299-305.
Interpretive Summary: Filariasis, malaria, dengue, yellow fever, and Japanese encephalitis are mosquito-transmitted maladies that contribute significantly to the burden of vector-borne diseases in tropical countries. Mosquito species variously associated with these diseases include Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus. The mint plant Orthosiphon thymiflorus is native to SE Asia where it is used in folk medicine as a diuretic, lotion, and poison antidote. In this study, Indian and ARS scientists determined the activity of O. thymiflorus leaf extracts against larvae of malaria, dengue, and filariasis vector mosquitoes. On average, 50% of the larval test population was killed within 24 h when using extract concentrations between 118 ppm and 228 ppm with the methanol extract most potent in this regard. These results indicate that extracts of widely available plants have excellent potential for use in local mosquito vector control programs.
Objective: To determine the larvicidal activity of hexane, chloroform, ethyl acetate, acetone, and methanol extracts of Orthosiphon thymiflorus leaves against Anopheles stephensi, Culex quinquefasciatus and Aedes aegypti. Methods: Larvicidal activity was determined in laboratory bioassays using various concentrations of leaf extract (50-450 ppm) and LC50 values calculated using probit analysis. Results: The LC50 of hexane, chloroform, ethyl acetate, acetone and methanol extracts of O. thymiflorus leaves against 3rd instar An. stephensi were 201.39, 178.76, 158.06, 139.22 and 118.74 ppm, respectively; against Cx. quinquefasciatus, 228.13, 209.72, 183.35, 163.55 and 149.96 ppm, respectively, and against Ae. aegypti 215.65, 197.91, 175.05, 154.80 and 137.26 ppm, respectively. Maximum larvicidal activity was associated with the methanolic fraction followed by the acetone, ethyl acetate, chloroform, and hexane extracts.