Digestive pectinolytic activity in the Sunn pest,Eurygaster integriceps Puton (Hemiptera: Scutelleridae)

Adults of Eurygaster integriceps were collected from the wheat field, dissected and their midguts and salivary glands were removed out. After centrifugation of the homogenates, the resulted supernatants were used as the source of enzyme. Pectinase activity was assayed using agarose plate and colorimetric assays. Pectinesterase and polygalacturonase activity was detected in the first and fourth part of the midgut, respectively. Colorimetric assays revealed more pectinase activity in the first part than the fourth part. No activity was detected in the salivary gland. Optimal pH for pectinase activity in the first part of the midgut was determined at pH set of 3, 4, 5, 6, 7, 8, 9 and 10. The results showed the optimum pH for pectinases occurred at pH 6. Maximum activity for the enzyme incubated at 20,30,35,40, 45, 50, 60, 70, 80, 90 and 100°C for 60 min was observed at 50°C. This is the first report of the presence of pectinases in a scutellerid bug.