Biochemical characteristics of digestive enzymes of codling moth, Cydia pomonella (Lepidoptera: Tortricidae)

Cydia pomonella (L.) (Lepidoptera: Tortricidae) is one of the significant pests of apples that causes irreparable damage to apple orchards every year. This study investigates the digestive enzyme profile of codling moth and assesses effectiveness of some metal ions and protease inhibitors on their activity. After rearing insects in the laboratory conditions (60% relative humidity, 25 ± 1 ºC, and 16 h light: 8 h dark), the digestive tract of the larvae was removed and dissected. After centrifugation of the digestive tube, the supernatant was used as an enzyme extract for biochemical assays. The optimum pH and temperature for the activity of alpha-amylase was 10 and 35 °C. The optimal acidity of general protease and lipase was 11 and 8. The zymogram of alpha-amylase confirmed the presence of two isoforms in the digestive tract of C. pomonella. The effect of tested ions on the activity of digestive enzymes was significant. copper ion increased the activity of both beta-glucosidase and lipase at the two studied concentrations include the concentrations 5 and 10 mM. Furthermore, the activities of trypsin and chymotrypsin-like were decreased by all ions compared to the control. The zymogram revealed the significant inhibitory effect of TLCK and TPCK on the activity of serine proteases, especially trypsin and chymotrypsin. The results of this study partially clarified the physiological aspects of the digestive system in the codling moth and evidences for the presence of carbohydrases, serin proteases and lipases. Further research could provide insight into the potential use of enzyme inhibitors in the management of this pest.