Insecticidal Activity of the Methanol Extracts of Some Tunicate Species against Aedes aegypti and Anopheles maculatus

Abstract

The methanol extracts of seven species of Malaysian tunicates (Clavelina picta, Eudisma obscuratum, Didemnum molle, Atriolum robustum, Phallusia sp., Didemnum sp. and Aplidium sp.) were investigated for their insecticidal activity against Anopheles maculatus and Aedes aegypti. The mortality values of the extracts on the adult mosquitoes were dose-dependent and increased with exposure period. The tunicate extracts demonstrated significant insecticidal effect after 3 h exposure with LC 50 values ranging from 0.03 to 3.79 µg ml -1 against An. maculatus and from 0.02 to 2.49 µg ml -1 against Ae. aegypti. The extracts of Didemnum sp. and Phallusia sp. were highly effective against Ae. aegypti with LC 50 values of 0.02 and 0.03 µg ml -1, respectively, while the extracts of Eu. obscuratum, Aplidium sp. and At. robustum showed similarly low LC 50 values against An. maculatus. The values were comparable to that of DDT, indicating that the tunicate extracts were as effective as the synthetic insecticide in killing the mosquitoes.