Enzymatic properties of α-amylase in the midgut and the salivary glands of mulberry moth, Glyphodes pyloalis Walker (Lepidoptera: Pyralidae)

The pyralid moth, Glyphode pyloalis Walker, is an important pest of the mulberry. Amylases are the hydrolytic enzymes that catalyze the hydrolysis of the α-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 α-amylase activity was assayed using the dinitrosalicylic acid procedure. The activity of α-amylase in the MG and the SG were 0.011 and 0.0018 μmol/min, respectively. The optimal pH and temperature for α-amylase were 9 for MG at 37–40 °C and 10 for SG at 37 °C respectively. Various concentrations of compounds (NaCl, KCl, MgCl2, Urea, EDTA, SDS and CaCl2) 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.