不同虫源和致害性的褐飞虱体内共生菌的种群动态

通过对不同地理种群和致害性的褐飞虱体内共生菌，在高温和抗性水稻品种作用下的种群动态研究表明，在正常湿度下褐飞虱体内共生菌的数量随若虫的生长发育而增加，5龄若虫期是共生菌增长的关键期；同一种群的褐飞虱秋季共生菌数量明显高于夏季。广西田间种群的短翅雌虫体内的共生菌数量显高于浙江省的杭州和龙游种群，经高温处理后，3个生物开共生菌数量均显减少，但其子代共生菌的数量在正常温度下马上恢复，与未经高温处理的褐飞虱共生菌数量基本相同，取食抗性品种的生物型1和田间种群的褐飞虱体内的共生菌数量均明显减少，取食抗性品种的第2代的共生菌又均比第1代少。这说明高温对共生菌的影响是暂的，而抗性品种的对共生菌的作用与褐飞虱种群对品种的适应性有关。

The population dynamics of symbiote in body of brown planthopper from different geographic fields and adapted to different resistant rice varieties

The quantitative changes of symbiote in different geographic and virulent popula- tions of brown planthopper (BPH) Nilaparuata lugens Stal, one of the most destructive pests on rice in China and other Southeast Asian countries, were monitored with treatments by high tem- perature and on resistant rice varieties in 1998 and 1999. The results showed that the 5th instar nymph was found to be the key period of symbiote growth in which propagated more than 50% of symbiote, although the number of symbiote mushroomed with the development of BPH, while higher number of symbiotes in BPH was recorded in autumn than in summer under nature tem- perature. The abundance of symbiote in BPH from Guangxi Province was markedly higher than that from Hangzhou and Longyou in Zhejiang Province. The number of symbiote in all tested biotypes was decreased significantly by the egg treatment under high temperature for 3 days, however, that in offspring of treated BPH was not difference with those in untreated BPH. The densities of symbiote in Biotype 1 and field population of BPH were reduced obviously on resistant rice varieties IR26, Mudgo and ASD7 as compared to on susceptible rice variety TN1 and much less symbiote was monitored in the second generation of BPH than in the first generation on resis- tant rice varieties. Those results implied that the high temperature influenced transitorily the dy- namics of symbiote in PBH and the effect of resistant rice varieties on symbiote would be closely associated with the adaptation of BPH to resistant rice varieties.