棉大卷叶螟的年生活史与种群动态

经过3年田间调查及室内饲养观察,绘制了江淮棉区棉大卷叶螟年生活史图。调查结果显示,该棉区棉大卷叶螟年发生5~6代,主要以第5代老熟幼虫越冬,越冬幼虫于次年4月中下旬化蛹,棉田幼虫始见于6月中下旬,但发生量少,进入7月中下旬后虫量开始上升,8~9月上旬达到高峰。近3年的调查数据表明,该棉区棉大卷叶螟种群数量发生大,其中常规棉田3年百株平均虫量达1 656~2 324头,并对棉花造成了较大损失。转基因棉田棉大卷叶螟种群数量受到明显抑制,3年百株虫量为619~1 358头。

Annual life cycle and population dynamics of Sylepta derogata

Based on field investigations and laboratorial rearing,the life cycle of Sylepta derogata was illustrated in Yangzhou of Jiangsu Province in 2005.The results showed that 5-6 generations of S.derogata occurred in Yangzhou annually and it overwintered as the 5th instar larvae,which pupated during the last ten days of April in the next year.The larvae could be found in cotton fields firstly in middle and late June,the population of which grew rapidly in late July,with the major peaks ranging from August to early September.Field investigations during 2003-2005 revealed that the natural population of S.derogata was large in Yangzhou.In conventional cotton fields,the larval density per 100 cottons was 1 656-2 324 and a very large natural population was observed.In transgenic cotton fields,the natural population was suppressed,with the larval density per 100 cottons as 619-1 358 over three years.