PARTIAL CHARACTERIZATION OF DIGESTIVE-TRACT PROTEINASES FROM WESTERN CORN-ROOTWORM LARVAE, DIABROTICA-VIRGIFERA

We have partially characterized the proteolytic activity within luminal contents of the digestive tracts of larvae of the western corn rootworm, Diabrotica virgifera LeConte. At least 15 proteinases were detected based on chromatographic behavior on ion exchange high-performance liquid chromatography and their mobility on sodium dodecyl sulfate gels containing gelatin. Inhibitors of proteolytic activity indicated that these enzymes are primarily sulfhydryl proteinases. Native polyacrylamide gel electrophoresis revealed that a single proteinaceous inhibitor, egg white cystatin, was capable of abolishing a substantial part of the proteolytic activity. Our data suggest, accordingly, that gene transfer experiments utilizing the cystatin gene may generate lines of maize which have increased resistance to western corn rootworm larvae.