Alpha-Amylase Enzymes of Tribolium castaneum (Herbst) and Callosobruchus maculatus (F.) And Their Response to A-Amylase Inhibitor from Rice أنزبم الألفا أمیلیز فى حشرتى خنفساء الدقیق الحمراء Tribolium castaneum (Herbst) وخنفساء اللوبیا Callosobruchus maculatus (F.) واستجابتهم لمثبط ألفا أمیلیز من الأرز

ABSTRACT Insect α-amylase has recently become a target of insect control strategies using plant-derived α-amylase inhibitors especially for the control of stored product insect pests. The first step to establish such strategy is to characterize the α-amylase enzymes in the target pest. In the current study, α-amylase was biochemically characterized in the larval and adult stages of Tribolium castaneum and Callosobruchus maculatus. T. castaneum was found to have higher α-amylase activity with lower temperature stability compared to that of C. maculatus. The optimum pH for α-amylase activity was 5-6. Zymogram pattern revealed the presence of two α-amylase isoforms with high molecule weight in T. castaneum. C. maculatus has two α-amylase isoforms in the adult stage and three isoforms in the larval stage. Rice α-amylase inhibitors was purified and found to have strong inhibitory effect against α-amylase of both insects and also negatively affected their life parameters.