次生代谢物在植物应对植食性昆虫防御反应中发挥重要作用。植物被昆虫取食后，会诱导激活植物防御信号通路，进而合成并积累大量植物次生代谢物。植物次生代谢物对植食性昆虫的防御作用方式多样，包括对昆虫产生致死作用、驱避和拒食作用、干扰酶活性、影响其生长发育和繁殖以及影响其体内共生菌，并通过招募昆虫天敌来间接防御。本文阐述了植物次生代谢物对植食性昆虫的防御作用相关研究进展，有助于了解次生代谢物在植物-昆虫互作中的作用，为构建生态友好和可持续发展的绿色防控模式提供理论依据。

Secondary metabolites play an important role in the defense of plants against herbivorous insects. Attack by herbivorous insects activates a plant’s defense signal pathway, causing it to synthesize a large number of secondary metabolites. These secondary metabolites have a variety of adverse effects on herbivorous insects, including lethality, repellence, appetite suppression and interference with enzyme activity. They can also influence insects’ growth, development, reproduction and symbiotic bacteria, and attract predators of herbivorous insects. This article reviews research on the defensive properties of plant secondary metabolites, and provides a theoretical basis for developing more environmentally-friendly, and sustainable, methods of pest control.