Ｂ．ｔ 杀虫剂对棉铃虫幼虫的杀虫效果受温度的影响变化很大，随着温度的降低，幼虫的死亡速度变慢，死亡高峰出现迟；从所进行的４ 个温度梯度处理结果来看，２０ ℃为一界限，等于或高于２０ ℃，Ｂ－ｔ 杀虫剂对２ 龄棉铃虫幼虫的杀死效果明显，低于２０ ℃，效果则较差。但在低温下Ｂ－ｔ 杀虫剂对幼虫取食与生长的抑制作用仍然很明显 B. t insecticides on the cotton bollworm larvae insecticidal effect varies greatly with the temperature, as the temperature decreases, the mortality of larvae slowed down, the peak appeared late death; from the results of the treatment of the four temperature gradient , 20 ℃ for a limit, equal to or higher than 20 ℃, B-t insecticides on the 2nd instar larvae kill bollworm effect is obvious, below 20 ℃, the effect is poor. However, the inhibitory effect of B-t insecticide on larval feeding and growth at low temperature is still significant