Salivary alpha-amylase activity of the stripped bug, Graphosoma lineatum: Changes during development

摘要

 Studying the digestive enzymes of true bugs is important in understanding the physiology of the digestive system and manner of injury to plants by these insects. In this study, the salivary α-amylase activity of the adults and nymphs was measured by using a special diagnostic kit and an autoanalyzer. Protein concentrations in all enzyme samples were determined by using bicinchoninic acid method and bovine serum albumin as the standard. The method of Yazdanian et al. used for removing the salivary glands under a stereomicroscope, and enzyme samples were prepared by the method of Cohen. In eggs (newly oviposited and 1- to 4-days old ones), no enzyme activity was observed. In different nymphal stages, enzyme activity in third instars (12.45 U/mg protein) had the highest mean that differed significantly from other means. Enzyme activity did not observe in enzyme samples of first instars. Age and sex of adult insects had a significant effect on enzyme activity, so that it was higher in females than males, and in 15- and 30-days old adults it was higher than those of other ages, especially in 20-days old adult females which had the highest value (44.57 U/mg protein). In addition, it found that salivary α-amylase activity in adults was correlated with their reproductive activities