Exploring Plant α-Amylase Inhibitors: Mechanisms and Potential Application for Insect Pest Control

α-Amylases are found in microbes, plants, and animals, including insect pests. They play crucial roles in catalyzing the hydrolysis of α-1,4-glucan bonds within starch, glycogen, and related carbohydrates, forming shorter oligomers. In green plants, these enzymes are pivotal for starch degradation during photosynthesis and seed germination, whereas in phytophagous insect pests, they predominantly facilitate seed parasitism by degrading raw starch granules. Amylase inhibitors in plants appear to function as part of their defense against pests and pathogens. In the context of insect pests, some of these amylase inhibitors can target α-amylases in the digestive system of certain insects. Both mono- and dicotyledonous plants harbor multiple genes encoding proteinaceous α-amylase inhibitors. Previous studies have demonstrated that α-amylase inhibitors, whether produced in vitro or overexpressed in transgenic plants, can exhibit entomotoxic activity against certain insect pests. Field trials involving transgenic plants that overexpress α-amylase inhibitors have been conducted, laying the foundation for the potential commercialization of crops engineered with these genes. Herein, this review explores the molecular interactions between plant α-amylase inhibitors and insect α-amylases, shedding light on the underlying mechanisms of action, structural diversity, and assessing the broader biotechnological applications of this promising strategy.