The action of C. quinquefasciatus gut extracts in the processing of Cyt1Ab1 was observed after 1 min of initiated the digestion, being most evident 10 min later and finally converted to 25 kDa fragment. For trypsin, the fragment of 26 kda appeared at 14 h of activation. The processing by chymotrypsin were generated intermediaries during the process, the 25 kDa appeared at 24 h.