Abstract: The occurrence of the third and fourth generations of Cnaphalocrocis medinalis (Guenée) in Anqing City,Anhui Province,a mixed cropping rice region,were studied systematically. The results showed that the third and fourth generations of C. medinalis appeared two peaks in Anqing with the main infested period on early maturity type of middle-season rice in single-cropping paddy field from late July to early August,and on late rice in double-cropping paddy field from late August to early September. According to the data of female ovarian dissection and light-trap catches,the local generation was in the majority in the third generation but with a partial immigrants;however,the fourth generation was basically emigrants. Comparison on the ovarian dissection data for the field populations of C. medinalis revealed that the fourth generation on late rice in the double-cropping paddy field would be resident and no emigration,but the population on early maturity type of middle -season rice in the single-cropping paddy field would emigrate for a long distance,while some of them could disperse to the nearby double-cropping late rice fields,in which the moths settled down and bred. Because of calefacient autumn and changes in cultivated rice varieties and planting systems,the planting area and ratio of single-cropping rice increased rapidly in Anqing since 1995 and formed the mixed cropping rice region. Compared with the double-cropping areas,the incessancy rice growing in mixed cropping region could provide more favorable habitat and food resources for C. medinalis,causing the sustained infestation in autumn.

Key words: Cnaphalocrocis medinalis, mixed cropping rice region, ovarian development, population characteristics, global warming

摘要： 对2007年安徽安庆单双混作稻区第3、4代稻纵卷叶螟发生规律的系统研究表明，第3、4代稻纵卷叶螟在安庆混作稻区有两个发生高峰期，单季早中稻在7月下旬至8月初，双季晚稻在8月下旬末至9月上旬。结合雌蛾卵巢解剖和灯诱数据，进行世代性质分析。结果表明，早中稻田第3代以本地繁殖世代为主，有部分迁入；第4代为本地虫源，大部分迁出，少部分滞留为害。对比两种不同类型稻田的第4代稻纵卷叶螟雌蛾卵巢解剖数据，发现安庆稻区单季早中稻稻纵卷叶螟第4代以迁出型为主，双季晚稻田为居留型，早中稻田稻纵卷叶螟除远距离迁飞外，也可直接转移扩散到附近晚稻田中滞留为害。滞留的原因包括两方面，一是近年来暖秋（9月份）频率增大；二是安庆单双混作稻区的栽培制度和水稻品种的变革，使得单季稻比例上升，水稻在生长季节中不间断地种植，为稻纵卷叶螟的栖居、繁殖和秋季滞留为害提供了条件。

关键词: 稻纵卷叶螟, 混作稻区, 卵巢发育, 种群特征, 全球变暖