CHYMOTRYPSIN INHIBITORS IN MOSQUITOS - ACTIVITY PROFILE DURING DEVELOPMENT AND AFTER BLOOD-FEEDING

Chymotrypsin and trypsin inhibitors persist throughout all development al instars of Aedes aegypti. After a blood meal, inhibitor activity ag ainst chymotrypsin was more than double that of sugar-fed females, but only weak activity was detected in midguts where proteinase inhibitor s has been thought to regulate proteinases during blood digestion. A f ourfold increase in the ratio of abdominal/thoracic inhibitor activity after the blood meal strongly suggested that fat body, or other abdom inal tissues, represent the major source of inhibitor. Chymotrypsin in hibitor activity was deposited in maturing oocytes. Similar results we re obtained with blood-fed Anopheles albimanus. Chymotrypsin inhibitor was active against different mosquito proteinases and against bovine alpha-chymotrypsin and trypsin, but not against subtilisin, pancreatic elastase, or fungal proteases; chymotrypsin inhibitors did not interf ere with bacterial growth. The hypothesis on the regulation of blood d igestion through the action of proteinase inhibitors during the gonotr ophic cycle was abandoned and its involvement in the phenoloxidase cas cade in the mosquito egg chorion is suggested instead. (C) 1997 Wiley- Liss, Inc.