FIG 1.

Larvae from the 456 strain of S. frugiperda are highly resistant to Cry1Fa toxin in Bt corn event TC1507 but not to Cry1Ca toxin compared to larvae from the Ben strain. Resistance in the 456 strain is transmitted as an autosomal recessive trait. Bioassays were conducted with fresh corn event TC1507 leaf tissue (A) or meridic diet contaminated with Cry1Ca toxin (B) and neonates from the Ben and 456 S. frugiperda strains. Neonates from 456♀ × Ben♂ (456F) and Ben♀ × 456♂ (456M) crosses were also used in the bioassay whose results are shown in panel A to test for genetic transmission of the resistance trait. The data presented are the mean mortality rates and corresponding standard errors calculated from the results from two bioassays with 64 larvae each per strain/cross (n = 2) for plant tissue bioassays or 32 larvae per Cry1Ca toxin concentration. Different letters represent significant differences between the mean mortalities (one-way ANOVA and post hoc Holm-Šidák test for multiple pairwise comparisons; P < 0.01).