eng International Academy of Ecology and Environmental Sciences Arthropods 2224-4255 2020-3-1 9 1 7 14 2 article Ashraf Oukasha Abd El-latif 1 2 Department of Plant Protection, Faculty of Agriculture, Sohag University, Egypt Activity of digestive enzymes (trypsin, chymotrypsin and alpha-amylase) in soluble protein extracted from the larval gut of Rhynchophorus ferrugineus was studied using specific substrates and enzyme inhibitors. Digestive enzyme activity showed a noticeable increase between day 5 and day 35. However, there was a noticeable decrease in the activity of trypsin protease on day 20. Maximum enzymes activity was observed at 40C and pH of 8-9 in case of trypsin and chymotrypsin and pH 7-8 in case of alpha-amylase. Extract of digestive enzyme were incubated with different inhibitors specific for different classes of enzymes. SBTI and TPCK inhibited both trypsin and chymotrypsin like enzymes while could not inhibit alpha-amylase activity. EDTA and urea inhibitors could inhibit the activity of alpha-amylase but have no inhibition effect against trypsin and chymotrypsin enzymes. Kinetic analysis revealed higher Km value and higher Vmax value for the trypsin specific substrate (BApNA) compared with the chymotrypsin specific substrate (BTpNA). On the other hands, the Vmax value recorded for BApNA substrate was 11 times more than of that recorded for BTpNA substrate. The kinetic analysis of alpha-amylase like activity revealed that the enzyme has strong affinity to it substrate with moderate Vmax value. Results of the current study provide a fundamental knowledge that can be used to devise control strategies against R. ferrugineus. http://www.iaees.org/publications/journals/arthropods/articles/2020-9(1)/digestive-proteases-and-alpha-amylase-of-red-palm-weevil-larvae.pdf Rhynchophorus ferrugineus trypsin chymotrypsin alpha-amylase enzyme inhibitors