Ｂｔ制剂防治棉铃虫“五忌”一忌选用伴孢晶体含量低或过期的产品。因为Ｂｔ制剂杀虫的主要有效成份是伴孢晶体，而不是芽孢的数量，而过期的产品中伴孢晶体毒性蛋白大部分已经钝化，丧失了杀棉铃虫活性。二忌在温度较低的条件下使用。Ｂｔ制剂防治棉铃虫的最佳温区是２５... Bt preparation control cotton bollworm “five bogey” a bogey selection companion crystal content is low or expired products. Because the main active ingredient in Bt formulation insecticide is the spore crystal, rather than the number of spores, most of the concomitant toxic protein in the expired product has been passivated, losing the activity of killing cotton bollworm. Second, avoid using under low temperature conditions. Bt preparation of cotton bollworm control the best temperature is 25 ...