EXAMINATION OF MIDGUT PROTEINASES OF THE ADULT SOUTHERN PINE-BEETLE (COLEOPTERA, SCOLYTIDAE)

The midgut of adult southern pine beetles, Dendroctonus frontalis Zimm ermann (Coleoptera: Scolytidae), contains digestive enzymes with optim al proteolytic activity in vitro near pH 7. General proteinase activit y was significantly inhibited by serine and cysteine proteinase class inhibitors, while limited activation by cysteine proteinase class acti vators was apparent. These results indicate that both cysteine and ser ine proteinases are present in the adult midgut. The presence of both proteinase classes in adult southern pine beetles coincides with previ ous studies showing widespread occurrence of these two classes of prot einases as digestive enzymes in midguts of other coleopteran species, but represents one of few beetle species known to possess both protein ase classes simultaneously.