Insect bioassay test using pods protein of pigeon pea against pod borer (Helicoverpa armigera)

Abstract

Insects are responsible for major crop losses in pigeon pea. Here we have conducted an experiment in laboratory to test pigeon pea pod proteins activity against H. armigera. The total protein was extracted from 40 g pods of nine cultivated pigeon pea genotypes and one wild type species Cajanus scarabaeoides IC15683. Proteins were precipitated at 80% ASF and followed by dialysis. Total protein was concentrated at a range of 1mg/ml. Method of insects rearing and the bioassay of insect were examined on the neonatal larvae of H. armigera in laboratory (25±2 0C) by feeding the protein extract incorporated in chickpea based artificial diet. 100µl of protein samples were uniformly coated on the surface of diet and allowed to get absorbed. Two insect larvae were released in each plates and their average weight was measured after 2, 4 and 6 days intervals. Mortality and percent growth retardation was calculated in comparison to control. Wild species showed growth retardation in larvae as compared to the rest genotypes. It has been observed that Protein extracts of cultivated pigeon pea genotypes did not showed any insecticidal activity or growth retardation in insect larvae while Cajanus scarabaeoides IC15683 showed retardation in growth as compared with cultivated genotype. Thus the result of the present investigation indicated that deep study of wild type pods protein will be helpful in future for developing insect resistance plant from natural plant proteins.