Animals depend on digestive amylases to break down and utilize the starch in their food sources, and insect larvae that develop in starch-containing seeds require these digestive amylases for their development and survival. An excellent illustration of this principle comes from the work on the genetic engineering of peas and azuki beans with the amylase inhibitor ?-AI-1 from the common bean, Phaseolus vulgaris. The adult coffee berry borer (Hypothenemus hampei), a major insect pest of coffee, has two major digestive ?-amylases that can be separated by isoelectrofocusing. The ?-amylase activity has a broad pH optimum between pH 4.0 and 7.0. Using pH indicators, the pH of the midgut was determined to be between pH 4.5 and 5.2. At pH 5.0, the coffee berry borer ?-amylase activity is inhibited substantially (80%) by relatively low levels of the amylase inhibitor (?AI-1) from the common bean, Phaseolus vulgaris, and much less so by the amylase inhibitor from Amaranthus. We used an in-gel zymogram assay to demonstrate that seed extracts can be screened to find suitable inhibitors of amylases. The prospect of using the genes that encode these inhibitors to make coffee resistant to the coffee berry borer via genetic engineering is discussed.

Index terms: ?-amylase, amylase inhibitor, coffee berry borer, Hypothenemus hampei.

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