Biological effects of neem on the pupation of Henosepilachna vigintioctopunctata Fab. on bittergourd
R. Shanmugapriyan and V. Dhanalakshmi
Neem derivatives were experimented for their effect on the pupae of Henosepilachna vigintioctopunctata (Fabricius) on bittergourd. Neem oil at 2.5 percent concentration demonstrated 53.33 percent mortality of pupae. The pupal mortality ranged from 13.3 to 50.0 percent when the pupae were topically treated with neem seed kernel extract at the concentration range of 0.25 to 2.5 percent. The efficacy of neem seed coat and bark powder extracts were lesser than neem oil, seed kernel and cake extracts. The malformation effect of neem oil at 2.5% was 26.6 percent. The malformation effect of neem oil is followed by neem seed kernel and cake extract. Synthetic insecticides did not prove their effect on adult malformation. Neem oil resulted in 80.0 percent of inhibition on adult emergence at 2.5 percent concentration. The order of the pupicidal effect of neem derivatives was neem oil ˃ seed kernel ˃ cake ˃ seed coat and bark powder extract.