Mosquito repellent activity of the methanol extracts of some ascidian species

Abstract

The methanol extracts of seven marine ascidian species (Clavelina picta, Eudistoma obscuratum, Atriolum robustum, Didemnum sp., D. molle, Phallusia sp. and Aplidium sp.) from Malaysia were investigated for their repellency effects against four vector mosquitoes (Anopheles maculatus, Aedes aegypti, Ae. albopictus and Culex quinquefasciatus). Mosquito repellent activity was assessed by using the test cage described in the American Society for Testing and Materials standard E951-83. The extracts showed a significant degree of repellency against the mosquitoes with ED50 values ranging from 0.0008 to 0.0746 mg cm-2. The repellency effects were dose-dependent and selective as the ED50 values showed variation towards the various mosquitoes. Amongst these, the extract of Didemnum sp., with an ED50 of 0.0008 mg cm-2 against An. maculatus, was the most effective, comparable to the value obtained with the standard repellent, deet.