Insect Growth Inhibitory Activity of Aqueous Fraction of Indian Bhant Tree, Clerodendron infortunatum L. (Verbenaceae) on Cotton Bollworm, Helicoverpa armigera (Hubner) (Noctuidae)

Insect growth inhibitory activity of aqueous fraction of Clerodendron infortunatum on third instar larvae of Helicoverpa armigera was assayed through topical application as well as diet incorporation method. By topical application, larval weight reduction was maximum 6.65% at the highest concentration, 5 DAT. Both larval and pupal weight reduction were directly proportional with treatment concentration. Larval duration increased significantly even at the lowest concentration. Maximum 16% abnormal pupae was formed at 0.001% concentration. Larval mortality was maximum 32% at the highest concentration which decreased with decreasing concentration and reached to 0% at 0.005%. At 0.001% concentration 64% normal adults were emerged which decreased to 28% at 0.5%. Thus, through topical application maximum growth inhibitory activity was 72% with GI₅₀ value of 0.0106%. Through diet incorporation method, again larval and pupal weight reduction was directly proportionl with treatment concentration. Maximum larval weight reduction was observed as 15.13% at 5 DAT with the highest concentration. Maximum abnormal pupae formed as 32% at 0.1% treatment concentration. Larval mortality showed similar trend with topical application method and at the maximum concentration was 40%. By diet incorporation method growth inhibition activity increased to 80% with GI₅₀ value of 0.0017%.