Biochemical characterisation of α- and β-glucosidases and α- and β-galactosidases from red palm weevil, Rhynchophorus ferrugineus (Olivier) (Col.: Curculionide)

The red palm weevil, Rhynchophorus ferrugineus (Olivier), is one of the most destructive pests of palm trees in the southeast of Iran. Digestion in the alimentary canal of the red palm weevil is facilitated by some carbohydrases. Results of the in vitro studies indicated the presence of α- and β-glucosidases and α- and β-galactosidases in the digestive system and haemolymph of this pest. In the digestive system of females, the activities of α-glucosidase and β-galactosidase were higher than those of β-glucosidase and α-galactosidase. Also, the specific activity of α- and β-glucosidases and α- and β-galactosidases in the female digestive system was much higher than that in larvae. Results showed that the highest activities of α- and β-glucosidases were at pH 5 and of α- and β-galactosidases at pH 4. The R. ferrugineus α- and β-glucosidases and α- and β-galactosidases have an optimum temperature activity at 50, 50-60, 40-60, and 40°C, respectively. A zymogram pattern in the native gel revealed that R. ferrugineus α- and β-glucosidases and α- and β-galactosidases in the digestive system showed 2, 3, 1 and 1 major bands, respectively. The activity of α-glucosidase in the digestive system of larvae and female adults was higher than that of the other carbohydrases. Therefore, it is the most important subject for further study and design of a new approach to the control of this pest using carbohydrase inhibitors.