Proteolytic activity in the midgut of Ectomyelois ceratoniae Zeller (Lepidoptera: Pyralidae), Pomegranate carob moth

Abstract

In this study, the proteolytic activity in the midgut of Ectomyelois ceratoniae as the major pest of pomegranate was investigated to find nature of specific proteases and their properties for adopting possible pest management procedure. It was found that fourth and fifth instar larvae had the highest proteolytic activity as well as specific proteinases including, elastase, trypsin-like, chymotrypsin-like and two exopeptidases. The optimal pH of general protease was 10 and 9 for azocasein, casein and hemoglobin as substrate. The optimal temperature of the total proteolytic activity in the midgut of E. ceratoniae was found 30 and 35 °C by using azocasein and casein as substrates, respectively. In case of hemoglobin, the enzyme showed the highest enzymatic activity at temperatures from 15 to 35 °C. There was no enhancement in the proteolytic activity by using different cations but SDS, citric acid and mercaptoetahnol significantly decreased the proteolytic activity in the midgut of E. ceratoniae. Using specific proteolytic inhibitors including PMSF, TLCK, TPCK, E-64, DTT and phenanthroline revealed
presence of serine proteases as the major proteases in the midgut of E. ceratoniae.