Screening of Different Extracts of Marine Macro Green Algae for Larvicidal Activity against Dengue Fever Mosquito, <i>Aedes aegypti</i> (Diptera: Culiadae)

Abstract

The present study larvicidal activities of hexane, chloroform, ethyl acetate, acetone and methanol extracts of Halimeda macroloba, Decsne, Caulerpa racemosa (Frosk) Weber-Van-Bosses and Ulva lactuca Lin, (Chlorophyceae) against Aedes aegypti. The marine macro green algae extracts were tested against early 4th instar larvae of A. aegypti using WHO protocol and concentrations of 200, 400, 600, 800 and 1000 ppm. The observed mortality was made 24 and 48 h after treatment, data was subjected to probit analysis to determine the lethal concentration (LC50 and LC90) of the treated larvae of the tested species.Among the tested extracts the maximum efficicacy was observed in the ethyl acetate extracts. The ethyl acetate extracts of the seaweeds showed the presence of terpenoids, tannins and phenolic compounds stronger than the other extracts. The results revealed that all the extracts showed varied levels of larvicidal activity against A. aegypti tested. However, the ethyl acetate extract of C. racemosa showed remarkable larvicidal activity against A. aegypti (LC50=579.9 and LC90=1255.4 ppm values at 24 h and LC50 =495.4 and LC90 =1073.9 ppm at 48 h) followed by U. lactuca (LC50=588.1 and LC90=1290.7 ppm values at 24 h, and LC50= 530.8 and LC90= 1160.0 ppm at 48 h), respectively. The lowest larval mortality was observed with hexane extract of H. macroloba against A. aegypti with values of LC50=1116.8 and LC90= 1824.5 ppm (after 24 h) and LC50=1059.9 and LC90=1768.3 ppm (after 24 h). The present studies indicate that the larvicidal activity and phytochemicals derived from the ethyl acetate extract of C. racemosa have the potential to be used as an ideal eco-friendly approach and effective mosquito vector control agent.