【摘要】 施用氮肥后可以直接或间接地通过对植物—害虫—天敌三者之间关系的干预、改变寄主植物内的营养成分和次生化学物质的含量等从正反两个方面影响捕食性天敌的捕食能力。而氮肥对寄生性天敌的作用主要是通过干扰寄生蜂的寄主搜索和选择行为、影响天敌自身的生长发育、生殖和成虫性比以及改变寄主植物的形态和天敌所处的生境等。稻田生态系统中施用氮肥不仅可以改进节肢动物的营养条件和生境,而且还可以通过水生无脊椎动物群落的变化改变整个食物链的结构和动态。在施用氮肥的稻株上黑肩绿盲蝽对褐飞虱卵和若虫的捕食能力明显下降。稻田中诱捕到的寄生蜂种群数量也显著减少。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。更多还原

【Abstract】 The application of nitrogen fertilizer affected positively and negatively the predation abilities both in laboratories and fields by its indirect and direct roles in the trophic relationship among host plants,herbivores and predators,the improvement of nutrients and the modification of allelochemicals in host plants.Whenas,the influences of nitrogen fertilizer on parasitism efficiencies were attributed basically to its interference through the host plants and herbivores in parasitism behavior of host selecting and foraging,growth,development,reproduction and adult sex ratio of parasitoids,meanwhile the morphological changes of host plants and the shift of habitants paid a partial impact in parasitism performance.The nitrogen fertilization not only improved the nutrients and habitats for arthropods but also altered the dynamics and structure of food web through the changing the aquatic invertebrate community in rice fields.The application of nitrogen fertilizer substantially reduced the predatory behavior of mirid bug,Cyrtorhinus lividipennis on eggs and its predation capacities both on eggs and young nymphs of brown planthoppers(BPH) Nilaparvata lugens on rice plants.It also significantly decreased population abundance of egg parasitoids of BPH due to the darkened rice leaf weakens the attraction of rice plants to parasitoids.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.更多还原