褐飞虱虫源的致害特性研究

】对浙江、广西和云南的褐飞虱致害性研究结果表明，１９９７年浙江虫源对ＩＲ２６和Ｍｕｄｇｏ苗期致害为９级，若虫存活指数大于５０，表明仍以生物型Ⅱ为主。广西和云南虫源均能致害抗虫品种ＩＲ２６，Ｍｕｄｇｏ，ＡＳＤ７和ＲａｔｈｕＨｅｎａｔｉ，高龄若虫在ＲＨ品种上的成活指数分别为７０．９和６６．７，说明这两个虫源产生了与生物型Ⅰ，Ⅱ和Ⅲ的致害性不同的新致害型。浙江虫源的若虫和成虫对不同抗虫品种的取食选择性有明显差异，成虫嗜食ＩＲ２６品种，而若虫对不同品种的选择性无显著差异。云南虫源若虫嗜食ＡＳＤ７，而成虫则嗜食ＴＮ１。浙江和广西褐飞虱将卵产在ＩＲ２６上，而云南虫源则产在ＴＮ１上。表明不同虫源褐飞虱对抗虫品种的取食和产卵选择性与其致害性不一致。

THE VIRULENCE CHARACTERISTICS OF VARIOUS POPULATIONS OF BROWN PLANTHOPPER

The virulence characteristics of brown planthopper (BPH), Nilaparvata lugens Stal, populations collected from Guangxi and Yunnan provinces in southern China and Zhejiang province in Yangtze Delta were studied for different resistant rice varieties. The results indicated that the Zhejiang population could successfully infest Mudgo and IR26 in 1997, showing the characters of BPH biotype 2. The Guangxi and Yunnan populations, however, could adapt the resistant varieties IR26, Mudgo, ASD7 and Rathu Heenati (RH), the nymphal survival indices of them on RH were upto 70.9 and 66.7 respectively. Those may imply that the BPH populations in Guangxi and Yunnan have shifted into a new biotype. In the free choice test, there was obvious difference in the feeding preference of nymph and adult of Zhejiang population, the adult preferred to feeding on resistant variety IR26 and the nymph chose the hosts randomly. Most eggs of Zhejiang and Guangxi population laid on IR26 and the Yunnan population, however, laid about 50% eggs on TN1. The virulance characteristics were not closely related to the feeding and oviposition preference.