JAYAPAL SUBRAMANIAM*, KADARKARAI MURUGAN, KALIMUTHU KOVENDAN, PALANISAMY MAHESH KUMAR, CHELLASAMY PANNEERSELVAM, THIYAGARAJAN NATARAJ, DURAISAMY AMERASAN AND KANDASAMY KALIMUTHU

Mosquito control is facing a threat due to mosquito resistance to synthetic insecticides. Insecticides of botanical origin may serve as suitable alternatives. During the present study the larvicidal and pupicidal activity of leaf extracts of Sphaeranthus indicus, Sesbania grandiflora and Calotropis procera against the first to fourth instar lavae and pupae of the laboratory–reared malarial vector, A. stephensi were evaluated. The dried plant materials were powdered by an electrical blender. From each sample, 500g powder was macerated with 1.5 litres of methanol for 8 hours, using Soxhlet apparatus, and filtered. The extracts were concentrated at reduced temperature on a rotary evaporator and stored at a temperature of 4°C. The plant extracts showed larvicidal and pupicidal effects against all larval instars and pupae. Larval mortality was observed after 24 hours of exposure. The maximum larvicidal activity was observed for methanolic extract of C. procera followed by S. indicus and S. grandiflora. No mortality was observed in the control. The observed mortality were statistically significant at Pstephensi were worked out. C. procera showed the highest mortality rate against the mosquito larvae in laboratory.