TRYPTIC AND CHYMOTRYPTIC ACTIVITIES IN DIFFERENT PARTS OF THE GUT OF THE FIELD CRICKET GRYLLUS-BIMACULATUS (ORTHOPTERA, GRYLLIDAE)

Tryptic and chymotryptic activities of the field cricket Gryllus bimac ulatus De Geer were assayed with benzyl-L-arginine ethyl ester and N-b enzoyl-L-tyrosine ethyl ester. In fed, but not in starved, crickets th e contents of the foregut were acidic and those of other parts of the gut were alkaline. Both tryptic and chymotryptic activities reached ma ximal levels at pH 8.0, and only the caeca, ventriculus, and hindgut p rovided optimal pH conditions. Among the tissue homogenates, the highe st activities of both enzymes were in caecal tissues. Tryptic activity was highest in the caecal lumen and chymotryptic activity was highest in the lumen of the ileum. The rectal lumen contained only very low l evels of their activities. When the enzymic activities were assayed at the ambient pH ol each gut region, the tryptic activity was still hig hest in the caecal lumen and the chymotryptic activities were equally high in the caecal and ileal lumen. Starvation for 5 d resulted in gre ater decreases of tryptic than chymotryptic activities in both the tis sues and contents, ana the foregut luminal activities of both enzymes were most severely affected.