OBJECTIVEThis study aims to reveal the effect of total ginsenoside on the protein content and digestive enzyme activities of 4th-instar Mythimna separata larvae, including alpha-amylase and cellulose, and explore the ecological function of total ginsenoside.

METHODWhile simulating natural growing condition indoors, 4th-instar M. separata larvae were fed by poison leaf disk method. The protein content was tested by Lowry Protein Assay Kit method, the activity of alpha-amylase was measured by dinitrosalicylic acid test, and the activity of cellulase was determined by the filter paper method.

RESULTThe total ginsenoside could reduce the content of protein of 4th-instar M. separata larvae significantly, and the activity of digestive enzyme, including alpha-amylase and cellulase. The protein content, alpha-amylase and cellulase activity of treatments were obviously lower than that of the control. Inhibition ratio of alpha-amylase and cellulase activity was positively correlated with total ginsenoside concentration: i. e. 20 g x L(-1) > 10 g x L(-1) > 5 g x L(-1).

CONCLUSIONThe results suggest that the inhibition effect of total ginsenoside on protein content and digestive enzymes may be one of the causes to antifeedant and dysplasia of M. separata larvae.