Synergistic Activity of Andrographis paniculata Nees Extracts Againstthe Larvae of the Malarial Vector Anopheles stephensi Liston(Diptera: Culicidae)

Abstract

An investigation has been made on the Deltamethrin and different solvent extracts of Andrographispaniculata Nees were evaluated under laboratory conditions for larvicidal activity against the malarialvector Anopheles stephensi Liston.Ethanolic extract with lethal concentration LC50 and LC90 of 35.47and47.43 after 24h and LC5025.22 and LC90 46.32 ppm after 48h, respectively was found to be the mosteffective, followed by Acetone, Methanol, Chloroform, Hexane, Petroleum ether and Benzene extracts.LC50 and LC90 for Deltamethrin  were 0.0036 and 0.0097 ppm after 24h and 0.0055 and 0.0085 ppmrespectively after 48h of exposure respectively. Combined formulations were evaluated for synergisticactivity and a 1:4 ratio of Deltamethrin and Ethanolic extract was observed to be more effective than 1:2and 1:1 ratios. Combinations of Andrographis paniculata extracts with Deltamethrin demonstratedhigher larvicidal activity, indicating synergistic activity.