Abstract:The dynamics of Cnaphalocrocis medinalis, planthoppers and their natural enemies were investigated in two kind rice paddies, the conventional management and ecological regulating rice paddy, in order to explore the effects of different rice paddy ecosystems on the main pests and their natural enemies. The results showed that the amounts of C.medinalis and planthoppers on peak in ecological regulating rice paddy were only 0.51 and 0.63 times of those in conventional management rice paddy, respectively. The amounts of C.medinalis and planthoppers on the vegetation around ecological regulating rice paddy were almost zero, while those on the vegetation around conventional management rice paddy were high up to 23.61 and 82.03 individuals per ten nets, respectively. Moreover, the ecological regulating practices increased the abundance of natural enemies significantly, and the amount of natural enemies in ecological regulating rice paddy and in its surrounding vegetation were up to 3.72 and 5.00 folds of those in conventional management rice paddy and in its surrounding vegetation, respectively. Meanwhile, the occurrence peaks of natural enemies were more synchronous with the insect pests in ecological regulating rice paddy than in the conventional management rice paddy. It was suggested that ecological regulating practices could be beneficial to the conservation of natural enemies and control of insect pests.