The pyralid moth, Glyphode pyloalis Walker, is an important pest of the mulberry. Amylases are the hydrolytic enzymes that catalyze the hydrolysis of the alpha-D-(1,4)-glucan linkage in glycogen and other related carbohydrates. Laboratory-reared fifth stadium larvae were randomly selected; the midgut (MG) and the salivary glands (SG) were removed by dissection under a dissecting microscope and alpha-amylase activity was assayed using the dinitrosalicylic acid procedure. The activity of alpha-amylase in the MG and the SG were 0.011 and 0.0018 micromol/min, respectively. The optimal pH and temperature for alpha-amylase were 9 for MG at 37-40 degrees C and 10 for SG at 37 degrees C respectively. Various concentrations of compounds (NaCl, KCl, MgCl(2), Urea, EDTA, SDS and CaCl(2)) had differential effects on the enzyme activity. Plant amylase inhibitors may play an important role against insect pests. Hence, the characterization of digestive enzymes and the examination of their inhibitors may be a useful tool in future management of this important mulberry pest.
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