COMPARATIVE TOTAL ACTIVITIES OF DIGESTIVE ENZYMES IN DIFFERENT GUT REGIONS OF THE HOUSE CRICKET, ACHETA-DOMESTICUS L (ORTHOPTERA, GRYLLIDAE)

The total luminal enzyme activity levels of carbohydrase (amylase, suc rase, maltase, trehalase), lipase, and protease were compared. Caecum, ventriculus, anterior hindgut, and posterior hindgut were assayed und er the pH conditions in each region to determine the importance of eac h region for the digestion of food. The pH of each gut region was regu lated and was not influenced by food. Food remained in the acidic (pH, 5.0) crop for 3-5 h, and most of the digestion of carbohydrates occur red there. No enzymes were secreted in the crop; rather, enzymes produ ced in the caeca were transported forward from the caecum into the cro p. The proventriculus ground the food and slowly released the crop mat erial into the ventriculus where it was buffered to a pH of 7.2-7.4. M ost of the total protease activity occurred in the crop and ventriculu s. Most of the absorption of digested food occurred in the relatively short ventriculus. It only required 30-50 min for the food to pass fro m the crop to the rectum. The hindgut or the contained bacterial symbi onts produced some enzymes, mainly lipase, and some absorption of dige st products, especially lipids, occurred in this region.