Larvicidal properties of Psychotria octosulcata (W. A. Talbot.) (Rubiaceae) crude extracts on human vector mosquitoes Aedes aegypti (Linn.), Culex quinquefasciatus (Say.) and Anopheles stephensi Liston
Gandhimathy Selvaraj and Jeyasankar Alagarmalai
Psychotria octosulcata plant extract potential in controlling mosquito larvae was investigated. The crude extracts from the plant leaves were obtained by soaking method using the solvents such as ethyl acetate, chloroform and hexane. The crude extracts were subjected to larvicidal activity of Aedes aegypti, Culex quinquefasciatus and Anopheles stephensi of IVth instar larvae at 48hrs. An. stephensi showed maximum larvicidal activity at a minimum LC50 value of 58.2ppm for ethyl acetate extract. Above 90% mortality was observed for ethyl acetate extract at LC50 62.2ppm and 65.7ppm for C. quinquefasciatus and A. aegypti respectively. The hexane also showed above 90% mortality for three species at 60-68ppm and chloroform showed comparatively lower mortality than other two solvents. The microscopic observations suggest that the extract has produced physical and physiological inconvenience for the survival of larvae. The results indicate that the plant extract has phytochemicals that are efficient to control mosquito larvae.