Ovicidal and Latent Effects of Pulicaria jaubertii (Asteraceae) Leaf Extracts on Aedes aegypti.

The control of Aedes aegypti with synthetic pesticides may result in adverse effects on wildlife and the environment. Bioactive plant extracts have been proposed as one of the alternatives to chemical pesticides used against mosquitoes. Here, we report on the ovicidal and latent effects of ethanolic, petroleum ether, and chloroform leaf extracts of Pulicaria jaubertii at 25 to 150 ppm each against the life stages of laboratory stain of Ae. aegypti. At 150 ppm, the ethanolic leaf extract resulted in 100% ovicidal activity, followed by petroleum ether extract (74%), and chloroform extract about 7% mortality. The ethanolic extract produced 100% larval and pupal mortality at both 75 and 50 ppm, while the petroleum ether extract produced 76.5 and 58.3%, respectively. The ethanolic extract recorded the highest percentage of adult mortality (72.7%) at the lowest concentration (25 ppm). At 25 and 50 ppm, the ethanolic extract resulted in 62.2 and 85.2% sterility index of Ae. aegypti females, respectively, as compared with the 0.1 and 3.5% sterility index caused by the chloroform extract at the same concentrations. In conclusion, P. jaubertii appears to have potential to be further evaluated as a mosquito control agent. Additional studies are needed on its mode of action, synergism with other products, and efficacy under actual field conditions.

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

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.