Larvae fed on fresh ear of field corn that expressed the Bt proteins ( Cry1F and Cry1F + Cry1A.105 + Cry2Ab2 ) , showed an 100 % mortality rate . Larvae fed on fresh ear of field corn that showed the Bt proteins ( Cry1F and Cry1F + Cry1A.105 + Cry2Ab2 ) , expressed an 100 % mortality rate .