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大螟原系水稻上的次要害虫,但自1977年发展杂交水稻后,便一跃而成为水稻的主要害虫之一.为了有效地控制大螟为害,我们对杂交水稻大螟的发生为害特点及种群变动原因进行了调查研究,现将初步结果整理于后.发生规律大螟在江苏一年发生3个完整世代,有的年份可发生不完全的4代.一般以3龄以上的幼虫形态在水稻、茭白、芦苇以及杂草根茬附近的表土下越冬.在越冬幼虫中,老熟幼虫约占半数或半数以上,余为未老熟的幼虫,但未发现1龄幼虫能够越冬.室内饲养观察,2龄幼虫冬前不能成活,3～4龄幼虫需摄取补充营养才能化蛹,5～6龄幼虫不摄取补充营养也能正常生育繁殖.在自然条件下,早春气温上升到10℃以上时,未成熟的幼虫开始活动,4月初为害夏熟作物,
Sesamia inferens are the primary pests on rice, but they have become one of the major pests in rice since the development of hybrid rice in 1977. In order to effectively control the damage of Sesamia inferens, we have the peculiar effect on the occurrence of Sesamia inferens And the reasons for the population changes were investigated, the preliminary results are now sorted out. Occurrence regular Sesamia in Jiangsu in three complete generations occurred in some years, some years may occur incomplete 4 generations usually 3 larvae larvae morphology Overwintering under topsoil near rice stubble, white reed, reed and weed stubble, the number of mature larvae accounted for about half or more than half of the overwintering larvae, while the remaining ones were immature larvae, but the first instar larvae were found to be overwintering. Breeding observation, 2nd instar larvae can not survive before winter, 3 ~ 4 instar larvae need to take supplemental nutrition in order to pupate, 5 ~ 6 instar larvae do not take supplemental nutrition can reproduce normally .In natural conditions, the temperature in early spring rose to 10 ℃ Above, immature larvae began to move early summer damage summer crops,