Abstract: Effects of nitrogen regimes on the population dynamics of white-backed planthopper (WBPH), Sogatella furcifera, and its predatory spiders on hybrid rice were determined in single season rice fields in Jinhua, China. The results showed that there was a similar tendency in WBPH population dynamics in the three tested hybrid rice fields with different nitrogen regimes, and the peak of population was found at the rice elongating stage. The abundance of WPBH population was significantly increased with the elevated application of nitrogen fertilizer, while the highest abundance of WBPH population was recorded during rice elongating and booting stages in the rice field of Shenliangyou 5814. Application of nitrogen fertilizer could obviously increase the number of predatory spiders before full panicle stage in all three tested rice fields. Three-way ANOVA indicated that the population dynamics of WBPH and spiders were significantly affected by nitrogen regime, hybrid varieties and their growth stages．

Key words: nitrogen regimes, hybrid rice, white\|backed planthopper (Sogatella furcifera), spider