alpha-amylases of the coffee berry borer (Hypothenemus hampei) and their inhibition by two plant amylase inhibitors

The adult coffee berry borer (Hypothenemus hampei Ferrari [Coleoptera: Scol ytidae]), a major insect pest of coffee, has two major digestive alpha-amyl ases that can be separated by isoelectric focusing. The alpha-amylase activ ity has a broad pH optimum between 4.0 and 7.0. Using pH indicators, the pH of the midgut was determined to be between 4.5 and 5.2. At pH 5.0, the cof fee berry boor a-amylase activity is inhibited substantially (80%) by relat ively low levels of the amylase inhibitor (alpha AI-1) from the common bean , Phaseolus vulgaris L., and much less so by the amylase inhibitor from Ama ranthus. We used an in-gel zymogram assay to demonstrate that seed extracts can be screened to find suitable inhibitors of amylases. The prospect of u sing the genes that encode these inhibitors to make coffee resistant to the coffee berry borer via genetic engineering is discussed. (C) 2000 Elsevier Science Ltd. All rights reserved.