These results implied that the reduction of predatory and parasitism natural control function should be one of the crucial factors to induce the outbreak of insect pest populations in rice fields applied with excessive nitrogenous fertilizer.

• 这些结果表明天敌对害虫自然控制作用的下降可能是稻田过量施用氮肥后害虫种群增加的主要原因之一。