Abstract: Experiments are carried out to study the chitinase in Viola faba leaves induced by Aphis craccivora on the basis of an insect-plant interrelationship.It is found that insect stress can induce plants chitinase activity and plant stress reaction level is related to the insect luantity.A highest chitinase activity is determined in 21 days under insect feeding.The experiments also show that plant can transmit the messages of insect stress from upper to lower alld increase its chitinase activity.The stress reaction fluctuates with time.It's concluded that plants resistant mechanism is the same under any adverse situations,that is to say.plant has a kind of convergent physiological stress reaction, and the dynamics of its chitinase activity is only an accompanying phenomenon.

Key words: Vicia faba, Aphis craccivora, Induction, Chitinase, Stress reaction