Anti-insect and antimicrobial effects of peptidase inhibitor partially purified from the seeds of Psoralea corylifolia

Abstract

Plant peptidase inhibitors have evolved to play a strong defensive role toward phytophagous insect pests. Peptidase inhibitor was partially purified from Psoralea corylifolia seeds of leguminaceae family by ammonium sulphate precipitation (20–80%) followed by dialysis with inhibitory activity against 64–72 h old larvae of Bactrocera cucurbitae. Different concentrations of the inhibitor (200, 400, 600, 800 and 1000 ppm) had a deleterious effect on the growth and development of the melon fruit fly larvae. The larval period, pupal period, and the total development period prolonged significantly, while percentage pupation and percentage adult emergence were drastically reduced. Nutritional indices viz. Mean Relative Growth Rate (MRGR) and Food Assimilated (FA) with respect to control were significantly lowered in treated larvae than in control. The inhibitory effect of peptidase inhibitor partially purified from P. corylifolia seeds increased significantly with an increase in the concentration of the inhibitor. It was also active against different strains of bacteria. These results show the potential of peptidase inhibitor partially purified from P. corylifolia seeds in insect pest control which can be used for improving plant protection.