湘北地区三化螟种群消长的原因探讨

本文根据湘北 4 9年水稻三化螟 Tryporyza incertulas( Walker)种群密度消长的历史资料 ,着重分析了 1996～ 1998年连续 3年三化螟在湘北猖獗为害的原因 ,即中稻、一季晚稻面积增加 ,杂交中、晚稻“双两大”的推广 ,晚稻的大面积早插都便于三化螟辗转繁殖为害 ;稻田春收作物——油菜的大面积种植 ,增加了三化螟的有效越冬虫源 ;水稻播期拉长及品种的多元化和栽培方式的多样化 ,使水稻危险生育期与蚁螟盛孵期吻合度加大 ;三化螟对农药的抗性增强和主害代发生期变得不整齐 ,增加了防治的难度

Population dynamics of Tryporyza incertulas(Walker) in the northern part of Hunan Province

Based on the forty\|nine years historical materials about the population dynamics of Tryporyza incertulas in the northern part of Hunan Province.The causes why T.incertulas had incurred great harm to the crops in the north of Hunan Province from 1996～1998 on end were analyzed.First,with the wider range of planting middle and late season rice and the early transplanting of late rice,at the same time,with the wide application of the raising of seedling in two periods, T.incertulas can easily propagate and then destroy the crops; second,rapes which are harvested in spring provide T.incertulas with rich food sources of insects; then,rice transplanting period has been lengthened,rice varieties and transplanting methods become diversified and variegated,which make the unsteady growing period of crops and the rush egg depositing period occur almost at the same time;finally, T.incertulas resistance against insectcide has become stronger and its main generation can reproduce and do harm to the crops in different periods.All these lead to the much more difficult prevention and cure of them.