GMOs are not killing bees. That is a hypothesis that has been disproved.
Please read the paper Duan JJ, Marvier M, Huesing J, Dively G, Huang ZY. 2008. A meta-analysis of effects of Bt crops on honey bees (Hymenoptera: Apidae). PLoS ONE 3:e1415 which has disproved the hypothesis that GMOs are killing bees