S. Ramya et al.


Biopesticides have gained prominence as potential plant protecting agents. Biological activity of solvent extracts of Catharanthus roseus L (G) Don. were evaluated against larvae of gram pod borer Helicoverpa armigera (Lepidoptera: Noctuidae). Antifeedant and larvicidal activity of methanol crude, petroleum ether, methanol fraction and ethyl acetate fraction of leaf extracts of C. roseus were estimated in the present study. Preliminary screening of the extracts was tested at a concentration of 1,000 ppm. The larval mortality was observed after 24h of exposure to the extracts. All extracts exhibited moderate larvicidal effects. However, highest larval mortality was observed in ethyl acetate fraction (4.1, 4.1, 17.4, 42.2, 55.6 and 84.5) of leaf extract of C. roseus, followed by methanol fraction (10.6, 12.7, 26.9, 59.4, 68.3 and 106.7) against the I, II, III, IV, V and VI instar larvae of H. armigera respectively. Further, the most active ethyl acetate fraction of C. roseus was used to estimate larvicidal activity. The results suggest that ethyl acetate fractions of leaf extract of C. roseus holds a potential to be used as biopesticide for the control of destructive polyphagous agricultural pest - H. armigera.