Abstract: Jasmonic acid (JA) is a naturally occurred growth regulator found in higher plants and a main signal molecule carrying information about injury.Its increased concentration in plants infested by herbivores can induce the wounded plants to produce defense responses which will affect herbivores.The application of exogenous JA to plants could imitate the effects of herbivores infestation.This study showed that applying exogenous JA on cabbage plants did not affect the survival of Plutella xylostella larvae,but retarded their development and reduced the pupal weight and female fecundity.