WHEAT AND BARLEY INHIBITORS ACTIVE TOWARDS ALPHA-AMYLASE AND TRYPSIN-LIKE ACTIVITIES FROM SPODOPTERA-FRUGIPERDA

The alpha-amylase activity was determined throughout the larval develo pment of Spodoptera frugiperda. Maximal activities with optimal pH in the range 8.5-9.5 were found in last instars. Protein preparations enr iched in heterotetrameric inhibitors from wheat flour were active towa rds gut amylases from last instars, while those corresponding to homod imeric and monomeric inhibitors showed low inhibition levels. These re sults were further supported by testing purified members of each inhib itor type and by analyzing the effects of the inhibitors on the amylas e isoenzyme pattern from native PAGE. High levels of trypsin-like acti vity were also found in gut extracts from last instars. Different gene tic variants of the major barley trypsin inhibitor were active against this gut enzyme. None of the other larval digestive protease activiti es (chymotrypsin-like, elastase-like, leucine aminopeptidase-like, and carboxypeptidase A and B-like) were inhibited, indicating that the ba rley inhibitor is specific towards trypsin-like enzymes.