Expressing of digestive amylase in various developmental stages of Eurygaster maura, an enzymatic approachAbstract : In order to identify and determine of ¥á-amylase expressing in various developmental stages of Eurygaster maura, a series of biochemical and enzymatic experiments was carried out. For this goal midgut ¥á-amylase was isolated and characterized. Enzyme samples from midguts of adults were prepared by the method of Cohen with slight modifications. The ¥á-amylase activity was assayed by the dinitrosalicylic acid (DNS) procedure, using 1% soluble starch as substrate. Then absorbance was read at 540 nm by spectrophotometer. Amylase activity was detected in the midgut of the insects which were collected from wheat fields during spring. Amylase activity in the midgut of feeding insects was 0.083 U/insect. ¥á-amylase activity was detected in the various nymphal stage. The results show that ¥á-amylase activity in the immature stages increase constantly up to the third-instar. There were no significant differences of enzyme activity between third, fourth, fifth nymphal stages and adults (0.0071 - 0.0083 (U/insect)). ¥á-amylase activity in first-nymphal stage was 0.0046 U/insect. Optimum temperature for the enzyme activity was determined to be between 30 to 40 ¢ªC. Optimum pH value for amylase was 6.5-7.