湖北棉区转Bt基因棉对棉铃虫的控制作用

2000-2001年通过田间系统调查，表明转Bt基因棉（品种为GK19）在湖北江汉平原棉区对棉铃虫抗性稳定。试验设3个处理：转Bt基因棉化防田（使用化学农药控制害虫）、转Bt基因棉自控田（依靠天敌控制害虫）及常规棉对照田（利用综合防治措施控制害虫）。从棉铃虫的第2代到第5代整个发生期内，即使在不进行化学防治的情况下，棉铃虫在Bt棉田的发生量也保持在极低的水平(最高百株虫量为12头)。室内饲养结果表明，转Bt基因棉对棉铃虫的生长发育（幼虫体重、蛹重）有较为明显的影响，使6龄幼虫体重减少25.6%，蛹重减少18.2%。棉铃虫幼虫取食转Bt基因棉组织后，发育迟缓，相对于常规棉喂养的整个发育历期延长17 d，使棉铃虫在田间的危害减少至少一个世代。另外，接虫试验表明，棉铃虫幼虫在常规棉上的取食时间是转Bt基因棉株上的6.1倍，极大地减轻了棉铃虫的危害程度。

Resistance of transgenic Bt cotton to the cotton bollworm in cotton fields in Hubei Province

Systematic investigations in an experimental cotton field showed stable resistance of GK19, a cultivar of transgenic Bt cotton, to the cotton bollworm, Helicoverpa armigera (Hübner). The experiment included three treatments. The first was a transgenic Bt cotton plot that used pesticides to control pests, the second was a Bt cotton plot that relied on natural enemies to control pests, and the third was a routine cotton plot that adopted IPM (integrated pest management) to control pests. Cotton bollworm populations in the transgenic Bt cotton plots were controlled at very low levels with the maximal density being 12 per 100 cotton plants, even if no pesticides was sprayed throughout their growth stage. Bioassay in the laboratory showed that the weights of 6th instars larvae and pupae from the colony reared on the Bt cotton were 25.6% and 18.2% less respectively compared to those raised on routine cotton. Cotton bollworms that fed on Bt cotton grew slower and their generation duration was at least 17 days longer than those that fed on non Bt cotton. This resulted In reduced damage to transgenic Bt cotton plants.