Interaction of insect digestive enzymes with plant protein inhibitors and host-parasite coevolution

A complex of new approaches was used to study the insect-plant coevolution by using cereal pest digestive alpha-amylases and proteinases and their proteinaceous inhibitors in cereals. During evolution, plants can weaken the destructive affects of insect hydrolases at the expense of inhibitors in various ways, including (1) increasing the inhibitor activity and heterogeneity, (2) increasing the complexity of an inhibitor set and (3) producing highly specific insect enzyme inhibitors and bifunctional amylase/proteinase inhibitors. Insects, in turn, can decrease the influence of inhibitors by (1) increasing digestive enzyme activities, (2) by modifying a set of related activities of various digestive hydrolases, (3) by decreasing enzyme sensitivity to inhibitors and (4) by destroying inhibitors in guts by proteinases.