Abstract: The types of injurious insects of major agricultural plants such as rice,wheat,cotton and other grain crops and the factors causing their succession were studied.The results indicated that the dynamic of insect population was closely related to environmental factors.Wellknowing the dynamic of insect population and the factors causing it was the key point to ecologically control the injurious insects.The ecological controlling might be made through a good cultivative strategies to keep“crop-insect-natural enemy”system in good balance.

Key words: laccase, forest ecosystem, gene diversity, TA cloning, vegetation