Evaluation of antifeedant activity of different parts of Calotropis gigantea against Helicoverpa armigera

Abstract

Milkweed plant or erukku (Calotropis gigantea R. Br.). (Family Asclepediaceae) a common waste land weed distributed in tropical and subtropical region of Asia. It possess many toxic principles which protects the crops from pest attack. Helicoverpa armigera (Hubner), is a polyphagous noctuid pest causing heavy damage to agricultural, horticultural and ornamental crops and developed resistance to insecticides posing problem to the farmers. Therefore alternate control measures needs to be developed which would be eco friendly and safe to the environment. In the present study, the antifeedant activity of C.gigantea was evaluated from its leaf, flower, stem, root and whole plant against third and fourth instar larvae, Helicoverpa armigera. The results suggested that10 per cent concentration of leaf, flower, stem, root and whole plant extract recorded the minimum area consumption (20.36%, 30.46%, 48.03 %, 59.00 % and 35. 06%) on third instar larvae. Similarly, 30.93%, 38.23%, 48.46%, 52.00% and 36.13% of area consumption in leaf, flower, stem, root and whole plant against fourth instar larvae of H.armigera. Higher the concentration of plant extracts, higher the antifeedant activity. Among the different plant parts, leaf extract showed strong antifeedant effect.