evaluating some properties of indian moth plodia interpunctella hübner (lep., pyralidae) alpha-amylase

abstract because of relation between digestive enzyme activity and feeding of insects that directly is in relation with the damage of insects; studying digestive enzyme systems is important in finding new control methods based on inhibiting digestive enzyme activity. recently using transgenic plants containing enzyme inhibitors is important in improving resistance of crops to pests because of safety of them to environment and biological control agents and also side and harm effects of conventional insecticides. information about properties of digestive enzymes is first step for using their inhibitors as a control method. in this study some properties of plodia interpunctella alpha- amylase including optimum ph; temperatures; stability and enzyme activity in different larval stages were investigated. insects were reared in controlled condition of 26 2˚c; relative humidity of 50% and 16:8 (l:d) h photoperiod. all experiments carried out in 4 replications. enzyme activity in temperature range of 25- 45˚c were studied; the optimum temperature was 37˚c for both male and female insects. the least enzyme activity was observed in 25˚c. the activity trend for both sexes in different temperatures was same. alpha-amylase was active in ph ranges of 5-10; and the trend of enzyme activity in different phs in both sexes was same. optimum ph for enzyme activity in male and female insects was 5.5. the lease enzyme activity for male and female insects was in phs of 8.5 and 7.5 respectively. enzyme activity in male and female insects was statistically different and its activity in female insects was more than males. this study also showed that the enzyme was stable in 4˚c for 40 days. enzyme activity in different larval stages was statistically different. the most enzyme activity was observed in 5th larval stage; and differences between enzyme activity in 3rd and 4th larval stages was not significant.