Peptidase inhibitor from Mucuna pruriens seeds inhibits the growth and development of Zeugodacus cucurbitae larvae

Zeugodacus cucurbitae (Coquillett) is an economically significant destructive pest of many vegetable and fruit crops. Peptidase inhibitors are a class of plant proteins that cause protein degradation and decrease the supply of amino acids, hampering insect pest growth and survival. To investigate the role of peptidase inhibitors in the control of this pest, the midgut peptidase activities and the growth and development of Z. cucurbitae larvae was studied when they were exposed to partially purified peptidase inhibitor from Mucuna pruriens (L.) DC. The results obtained showed a decline in larval survival, pupal weight and nutritional indices. The results also revealed that after 24, 48 and 72 h of treatment, peptidase inhibitor partially purified from M. pruriens seeds inhibited the complete proteolytic activity of larvae. It exerted effect on midgut peptidases at a stage where Z. cucurbitae larvae feed voraciously thereby prolonging the larval cycle and reducing pupal weight. These results provide quantitative information on the ability of peptidase inhibitors to control Z. cucurbitae and other destructive pest, avoiding chemical pesticides.