Abstract: The induction of plant proteinase inhibitor (PPI ) by insects has been the subject of considerable research interest. After being attacked by insects some plants can release proteinase inhibitor inducing factor (PIIF) at the site of injury. PIIF stimulates the production of systemin which activates the synthesis of jasmonic acid through the octadecanoid pathway. Jasmonic acid activates the PPI gene causing new PPI to be synthesized. On the other hand, insects can develop adaptations to PPI through the following mechanisms: （1） changing the sensitivity of the insect proteinase to PPI; （2）decomposing PPIs; （3） feeding excessively and interfering with the PPI production signal pathway. The signal molecules and their functions in inducing PPI production and the adaptation to PPI by insects are reviewed.

Key words: plant proteinase inhibitors, herbivorous insect, induction, adaptation