Biochemical characteristics of carbohydrase and serine protease enzymes of beet moth, Scrobipalpa ocellatella (Lepidoptera; Gelechiidae)

Characteristics of the digestive enzymes of the fifth instar larvae of the beet moth were determined to achieve a superior understanding of the digestive physiology of the pest. After dissecting the larval digestive tube, optimum acidity for the activity of α-amylase and α-glucosidase was obtained 8–9, and 8 for β-glucosidase, respectively. The optimum temperatures were 35 °C and 35–40 °C for α-amylase activity and for α- and β-glucosidase, respectively. The zymogram displayed the existence of three α-amylase isoforms in the digestive tract of this insect. The maximum activity of general protease was determined in the digestive tract of this pest using azocasein substrate in the pH range of 10–11. Furthermore, the optimum temperature was 35 °C for general protease. The metal ions including iron, magnesium, manganese, zinc, and copper at 5 and 10mM concentrations had a significant influence on the activity of α-amylase, α- and β-glucosidase, trypsin, chymotrypsin, and elastase enzymes. Zymogram confirmed the significant inhibitory effect of PMSF and TLCK on the activity of serine proteases, especially trypsin. The results of this research have determined to some extent the digestive system physiology and the digestive enzymes activity range in S. ocellatella. Certainly, Study on the characteristics of digestive enzymes of beet moth can be the starting point for further studies on the use of enzyme inhibitors and the possibility of preparing new methods to control this key sugar beet pest.