Field evaluation of repellency effect of some plant extracts against mosquitoes in Egypt.

Abstract

Sixteen ethanolic and petroleum ether extracts of 4 indigenous plants namely Echinochloa stagninum (Gramineae), Phragmites austra-lis (Poaceae), Avicennia marina (Avicenniaceae) and Artemisia monosperma (Compositae), were evaluated on human volunteers, and compared with Off! (Deet or N.N.diethyl toulamide), a commercial plant-based repellent against wild mosquitoes in Tanbol District about 15 km north to El-Mansoura city. The repellent action of the plant extracts tested varied depending on the plant species, part, solvent used in extraction and the extract dose. The petroleum ether extraction was more effective in exhibiting the repellent action against the mosquito as compared with ethanolic extraction. At the lowest concentration (5%), complete protection was attained by petroleum ether extracts of Ar. monosperma leaves and A. marina fruits 4h & 1h post-application, respectively. While the A. marina fruits, Ar. monosperma stems extracts and Off! showed significantly less repellency (P < 0.01) (95.7, 80.8 & 78.9%; respectively) after 4h from treatment. A. monosperma leaves especially proved potential candidate for use in developing commercial repellents as an alternative to conventional synthetic chemicals, particularly in community vector control applications.