Fig. 3From: Efficiency of cotton bollworm (Helicoverpa armigera Hübner) control of different Bt cotton varieties in North ChinaThe changes in corrected mortality and Bt protein content. a to c The changes in corrected mortality at the second, third, and fourth cotton bollworm generations from 2008 to 2015; d to f the changes in Bt protein content at the seedling, bud, and boll stages from 2008 to 2015. The error bars are SEsBack to article page