Examination of Midgut Proteinases of the Adult Southern Pine Beetle (Coleoptera: Scolytidae)
The midgut of adult southern pine beetles, Dendroctonus frontalis Zimmermann (Coleoptera: Scolytidae), contains digestive enzymes with optimal proteolytic activity in vitro near pH 7. General proteinase activity was significantly inhibited by serine and cysteine proteinase class inhibitors, while limited activation by cysteine proteinase class activators was apparent. These results indicate that both cysteine and serine proteinases are present in the adult midgut. The presence of both proteinase classes in adult southern pine beetles coincides with previous studies showing widespread occurrence of these two classes of proteinases as digestive enzymes in midguts of other coleopteran species, but represents one of few beetle species known to possess both proteinase classes simultaneously.