Selection and characterization of Spodoptera frugiperda (Lepidoptera: Noctuidae) resistance to MON 89034 × TC1507 × NK603 maize technology

The transgenic maize MON 89034 × TC1507 × NK603 expressing Cry1A.105, Cry1F and Cry2Ab2 proteins has been used for controlling fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith), in Brazil since 2010. To design resistance management strategies, we selected and characterized the resistance to MON89034 × TC1507 × NK603 maize in a field-derived strain of FAW and investigated fitness costs associated with resistance. In greenhouse assays, more than 64% of neonates from resistant strain (RR) survived on MON 89034 × TC1507 × NK603 maize plants and produced fertile adults. In contrast, neonates from susceptible (SS) and heterozygous strains did not survive on MON 89034 × TC1507 × NK603 maize plants, indicating that resistance is functionally recessive. In laboratory assays, individuals from the RR strain fed on MON 89034 × TC1507 × NK603 maize presented similar life table parameters of those fed on non-Bt maize. However, life history studies with non-Bt maize to investigate fitness costs revealed that the RR strain had a ∼4 d longer egg-to-adult period, 9% reduction in the survival rate until adult stage, and ∼ 35% lower reproductive rate than SS and heterozygous strains. In summary, our results showed that the resistance of FAW to MON 89034 × TC1507 × NK603 maize is functionally recessive and associated with relevant fitness costs. Therefore, the adoption of refuge areas as a resistance management strategy can prolong the lifetime of MON 89034 × TC1507 × NK603 maize in Brazil.