Quantification and kinetics of the decline in grass grub endopeptidase activity during initiation of amber disease

• Published in: Journal of invertebrate pathology 2004-07, Vol.86 (3), p.72-76
• Main Authors: Jackson, Trevor A, Christeller, John T, McHenry, Jane Z, Laing, William A
• Format: Article
• Language: English
• Subjects: alpha-Amylases - metabolism; Amber disease; Animals; Biological and medical sciences; Biological control; Chymotrypsin - metabolism; Coleoptera - microbiology; Coleoptera - physiology; Control; Costelytra zealandica; Digestive System - enzymology; Digestive System - microbiology; Down-Regulation; Endopeptidase; Endopeptidases - metabolism; Esterases - metabolism; Exopeptidases - metabolism; Feeding Behavior; Fundamental and applied biological sciences. Psychology; Grass grub; Insect Proteins - metabolism; Larva - enzymology; Larva - microbiology; Midgut proteinases; Pancreatic Elastase - metabolism; Phytopathology. Animal pests. Plant and forest protection; Protozoa. Invertebrates; Scarabaeidae; Serratia - pathogenicity; Serratia entomophila; Serratia proteamaculans; Trypsin - metabolism; Virulence
• ISSN: 0022-2011; 1096-0805
• DOI: 10.1016/j.jip.2004.04.003

Amber disease in the grass grub ( Costelytra zealandica White) (Coleoptera: Scarabaeidae), caused by strains of the bacteria Serratia entomophila or S. proteamaculans, is characterised by cessation of feeding and clearance of the midgut. Analysis of the midgut enzyme activity in diseased grass grub larvae showed that proteolytic activity was reduced to low levels. The endopeptidases, trypsin, elastase, and chymotrypsin, were all markedly reduced in activity whereas the exopeptidases (leucine-aminopeptidase and carboxypeptidase A and B) were much less affected. There was no effect on the non-proteolytic enzymes, esterase and α-amylase. Sequential analysis of enzyme levels in the gut during onset of disease showed that proteolytic activity dropped after cessation of feeding and preceded gut clearance. In starved, uninfected larvae enzyme activity levels remained high, indicating that decline in enzyme activity is not associated with absence of food and cessation of feeding, but with the onset of disease.