Effects of entomopathogenic bacterium Photorhabdus temperata infection on the digestive enzymes of Diatraea saccharalis (Lepidoptera: Crambidae) larvae.

This study investigated the effects of Photorhabdus temperata infection on the activities of digestive enzymes of the sugarcane stalk borer Diatraea saccharalis. Non-infected D. saccharalis larvae present a major alpha-amylase, several proteinases, three sucrose hydrolases and two alpha-glucosidases in their midgut. Analysis of these hydrolases by electrophoresis and "in gel" assays showed that the activities of all enzymes decreased following infection, with an initial decline observed 12 h after infection. The activities of alpha-glucosidases decreased by 50% twelve hours after infection, whereas, at this time, the alpha-galactosidase activities decreased by 70%. Interestingly, the animals died 48 h after infection, but approximately 5% of all the enzymes tested remained active in the midgut following host death. At this time, most of the cultivable native intestinal bacteria had died.