【作者】 吕仲贤；

【导师】 胡萃； 俞晓平； KL Heong；

【作者基本信息】 浙江大学 ， 农业昆虫与害虫防治， 2003， 博士

【摘要】 褐飞虱Nilaparvata lugens(Stl)属于季节性、迁飞性、r-对策和爆发性害虫，是东南亚水稻生产国最主要的害虫之一。20世纪60年代中期的“绿色革命”以后，由于矮秆、早熟、宽叶和高产的水稻新品种的大面积推广和应用、复种指数的提高以及农药和化肥的大量施用导致褐飞虱种群密度大幅度提高，使其从次要害虫转变为最主要的害虫之一。氮肥和高毒广谱杀虫剂的大面积连续施用被认为是褐飞虱大发生的主要原因。但是，氮肥在增加水稻产量的同时是否真正引起水稻对害虫的敏感性和害虫与天敌关系的变化，从而影响自然控制效能，导致褐飞虱等的大发生，以及氮肥影响水稻、褐飞虱和天敌之间关系的生态学机理等尚不明确，为此，在国际水稻研究所进行了氮肥对水稻植株抗性、褐飞虱生态适应性以及主要天敌自然控制能力的影响及其生态学机理的研究，为更好的水稻害虫和营养综合管理(IPNM)提供理论依据。主要研究结果如下： 1、氮肥对SPAD值的影响及其与稻株含氮量的关系 水稻叶片的SPAD值(叶绿素含量)与氮肥的施用量呈极显著的正相关。但同一氮肥施用量的重复间稻株叶片的SPAD值有显著差异，说明稻株的个体差异较大。水稻植株的含氮量与叶片的SPAD值也呈极显著的正相关，其关系可以表达为：N％=0.1151×SPAD-1.2772。 2、氮肥对稻株含水量和伤流液的影响及其与水稻对褐飞虱为害耐性的关系 随着稻株含氮量的增加，稻株的含水量和相对含水量均显著增加，但叶鞘伤流液总量却明显减少。被褐飞虱若虫为害后，高氮肥施用量稻株的相对含水量显著低于低氮肥施用量稻株的相对含水量。这些结果可能是导致高氮肥条件下稻株对褐飞虱为害的敏感性增加的重要原因，最终导致稻株含氮量的增加对褐飞虱为害的忍耐性下降。 3、稻株含氮量对褐飞虱产卵和取食行为的影响 温室内自由选择试验表明，无论饲养在高氮还是低氮稻株上的雌成虫均喜欢将卵产在含氮量较高的稻株上，不同种群褐飞虱的产卵量均与稻株含氮量呈极显著的正相关，产卵量E=85.036N％-82.602。随着稻株含氮量的增加，叶鞘下部的产卵量比例增加，而在叶鞘上部和叶片上的产卵量比例下降。成虫和若虫在低含氮量稻株上的取食频率明显比在高含氮量稻株上的取食频率高。饲养在低氮稻株上的若虫在取食低氮稻株时的取食频率最高，而饲养在高氮稻株上的若虫在取食高氮稻株时的取食频率最低。说明褐飞虱的取食频率与寄主植物、饲料植物和褐飞虱对寄主植物的适应性均有关。 4、稻株含氮量对褐飞虱生态适应性的影响 不同褐飞虱种群的若虫存活率随稻株含氮量的增加而显著提高，其变化范围在60％至100％之间，而在相同含氮量的稻株上连续饲养数代后，不同代别之间的若虫存活率无显著差异。但是，随着取食代数的增加，在高氮稻株上的若虫历期显著缩短、雌成虫鲜重和生殖力增加、成虫寿命逐渐延长和卵孵化率提高。稻株含氮量对褐飞虱子代数量和生物量的影响随着连续饲养时间的延长有一定的累积效应，在高氮稻株上逐代增加，而在低氮稻株上却逐代下降。5、稻株含氮量对褐飞虱抗逆性的影响 若虫密度对若虫存活率的影响随密度提高而增强、随稻株含氮量的提高而下降，而且若虫密度的增加和稻株含氮量下降均显著延长若虫的历期和降低雌雄成虫的比例。在高温情况下，在高含氮稻株上的褐飞虱成虫和若虫存活率、成虫生殖力和卵孵化率均显著高于在低含氮稻株上的褐飞虱，而且对高温耐性的差异随在不同含氮稻株上饲养代数的延长而增强。高氮稻株上的褐飞虱雌成虫的耐饥力和若虫对暖嗓酮的耐性均大于饲养在低氮稻株上的褐飞虱。结果证明田间施用过量氮肥后褐飞虱种群的抗逆性可能增强。6、稻株含氮量对褐飞虱天敌行为和生态适应性的影响 不同种群的黑肩绿盲螃均喜欢在高氮含量的稻株上捕食褐飞虱卵和产卵，被捕食褐飞虱卵的数量与稻株含氮量有极显著相关性。在水稻叶片和叶鞘同时有褐飞虱卵存在的情况下，无论高氮稻株还是低氮稻株上的黑肩绿盲螃均显著地选择捕食叶片上的卵，这在低氮稻株表现更明显。 在没有褐飞虱卵存在的情况下，黑肩绿盲螃不能在低含氮量的稻株上完成生活史，而在高氮稻株上的若虫存活率可达70－85％。在含有褐飞虱卵的高氮稻株上的黑肩绿盲峙种群的生态适应性参数如发育速率、雌成虫体重和寿命以及生殖力均显著高于低氮稻株上的参数值，但是若虫存活率和雄成虫寿命则无显著差异． 在漫射光条件下，不同种群的缨小蜂雌成虫均显著选择寄生在低氮稻株上的褐飞虱卵，被寄生的卵量随稻株含氮量的增加显著减少。但在黑暗条件下，所有缨小蜂种群对不同含氮量稻株上褐飞虱卵的寄生均无显著差异，说明光在缨小蜂对不同含氮量稻株上褐飞虱卵的寄生选择中起着重要的作用。在稻株不同位置上，叶片中脉内的褐飞虱卵被寄生的量最高，上部叶鞘次之，下部叶鞘最少。根据叶色卡不同级别的色泽亮度和不同含氮量水稻叶片的叶色卡级别，模拟出不同含氮量稻株对缨小蜂的相对吸引能力，Y＝＝．2．2285No＋16．213。结果说明过量施用氮肥后稻株叶色更多还原

【Abstract】 Brown planthopper (BPH), Nilaparvata lugens (Stal), characterized by its monsoon migration and r-strategy life pattern in East Asia, is an important insect pest in the Asian rice grow n region. It has increased in abundance and shifted from minor to major pest since the mid-1960’, due to the adoption of new rice productive practices such as planting widely of semi-dwarf, early mature, wide blade and high yield varieties, increasing cropping index, applying chemical fertilizers and pesticides. The excessive application of nitrogen fertilizer was considered to be the key factor to trigger the increase of BPH populations and frequencies of "hopper burn". However, the ecological mechanism on the influence of nitrogen nutrient on tritrophic interactions between BPH and its host rice and natural enemies is still unclear, especially on the changes in ecological fitness of BPH and its natural enemies continuously fed on rice plant with high nitrogen content, and on the relationship between nitrogen nutrient and the effective natural biological control functions.The main objectives of this research are to quantify the effect of nitrogen nutrient on the populations of BPH in fitness and their tolerances to adverse environmental stresses, and to assess the impact of nitrogen in the natural biological control functions, for a better integrated pest and nutrient management (IPNM) for rice.1. Effects of nitrogen regimes on the SPAD readings of rice leaves and the relationship between SPAD readings and the nitrogen content of rice plantsThe SPAD (the content of chlorophyll) readings of rice leaves at different rice growth stages were positively related to the rates of nitrogenous fertilizer, however the significant differences in SPAD readings were recorded among the replications of rice plants with the same rate of nitrogenous fertilizer. The nitrogen content of rice plants increased significantly with the increase of leaf SPAD readings both at different rice growth stages and different rice growing seasons, and the relationship between SPAD readings and nitrogen content of rice plants can be expressed as: N%= 0.1151 SPAD - 1.2772.2. Effects of nitrogenous fertilizer on water content, sap flow and tolerance to the brown planthopper of rice plantsBoth water content (WC) and relative water content (RWC) of rice plants were significantly increased, while the sap amount flowed from leaf sheath of rice plants were statistically reduced, with the increase of nitrogen content in rice plants. The RWC, which is more sensitive than WC to the change in nitrogen content of rice plants, in rice plants applied with high nitrogenous fertilizers strongly decreased by the injury of BPH nymphs. These may be the key factors to decrease the tolerance to BPH injury of rice plants with the increasing application of nitrogenous fertilizer.3. Effects of nitrogen content of rice plants on the oviposition and feeding behavior of the brown planthopperIn the free choice tests conducted in greenhouse, all adult females of BPH populations continuously fed on the rice plants both with high (N2) and low (N0) nitrogenous fertilizers preferred to laying their eggs on rice plants with a higher nitrogen content. The relationshipbetween numbers of BPH eggs laid (E) and the nitrogen content of host plants (N%) can be statistically regressed as: E = 85.036 N%-82.602. The numbers of eggs laid on the bottom of leaf sheath increased and those laid on the leaf blade decreased, when the nitrogen content of rice plants was increased. More adults selected to feed on rice plants with high nitrogen content than on those with low nitrogen content, while no obvious differences were found in feeding preference of BPH nymphs.Both nymphs and adults more frequently fed on NO rice plants than on N2 rice plants. The highest feeding frequencies of nymphs were found on NO rice plants in those nymphs that reared successively on NO rice plants. The feeding rates of newly emerged adult females were significantly increased with increase of the nitroge更多还原