Btk selected population with 4.1 fold to Btk caused 2.3 , 3.1 , 2.3 fold cross resistance to Bta, Cry1Ac, Cry1Ac+1C, respectively, and no cross resistance to Cry2A. There is no cross resistance to methomyl, phoxim, cypermethrin in these selected colonys.

• Btk汰选种群对 Btk的抗性指数为 4 .；1倍；对 Bta、Cry1Ac、Cry1Ac+1C的交互抗性为 2