The diamondback moth, Plutella xylostella (L.) (Lepidoptera, Plutellidae), is one of the most destructive pests attacking economically important crucifers.It is a rapidly reproductive species with around 20 generations per year in tropical regions where crucifers are grown throughout a year.Juvenile hormone (JH) has been proved to play a crucial role in stimulating reproduction of some insects including P.xylostella.