A Nonhost Peptidase Inhibitor of ~14 kDa fromButea monosperma(Lam.) Taub. Seeds Affects Negatively the Growth and Developmental Physiology ofHelicoverpa armigera

Abstract

Helicoverpa armigerais one of the major devastating pests of crop plants. In this context a serine peptidase inhibitor purified from the seeds ofButea monospermawas evaluated for its effect on developmental physiology ofH. armigeralarvae.B. monospermapeptidase inhibitor on 12% denaturing polyacrylamide gel electrophoresis exhibited a single protein band of ~14 kDa with or without reduction.In vitrostudies towards total gut proteolytic enzymes ofH. armigeraand bovine trypsin indicated measurable inhibitory activity.B. monospermapeptidase inhibitor dose for 50% mortality and weight reduction by 50% were 0.5% w/w and 0.10% w/w, respectively. The IC50ofB. monospermapeptidase inhibitor against totalH. armigeragut proteinases activity was 2.0 µg/mL. The larval feeding assays suggestedB. monospermapeptidase inhibitor to be toxic as reflected by its retarded growth and development, consequently affecting fertility and fecundity of pest and prolonging the larval-pupal duration of the insect life cycle ofH. armigera. SupplementingB. monospermapeptidase inhibitor in artificial diet at 0.1% w/w, both the efficiencies of conversion of ingested as well as digested food were downregulated, whereas approximate digestibility and metabolic cost were enhanced. The efficacy ofButea monospermapeptidase inhibitor against progressive growth and development ofH. armigerasuggest its usefulness in insect pest management of food crops.