Native insect resistance in corn can add durability to the current commercial varieties that have transgenic resistance to corn earworm (Helicoverpa zea Boddie) and fall armyworm (Spodoptera frugiperda J.E. Smith). Inbred lines and experimental hybrids developed by the corn breeding program of the Texas A&M AgriLife Research-Lubbock have putative insect resistance based on observations in field breeding nurseries. To verify native insect-based resistance, 19 genotypes (12 nontransgenic inbred lines and seven hybrid comparators including a transgenic Bt-hybrid) with insect resistance were evaluated in the field to assess the resistance to feeding by natural and laboratory reared colonies of corn earworm and fall armyworm. Agronomic performance and kernel quality of the corn genotypes were evaluated by yield and aflatoxin content. Larval performances were also considered in confirming resistance. This research tested the hypothesis that advanced bred corn genotypes with putative native resistance to corn earworm and fall armyworm identified in a breeding nursery are resistant based on replicated field and larval feeding experiments. Putative native insect-based resistance to corn earworm were confirmed among the nontransgenic inbred lines and hybrids in the field trial as expressed by lessened corn earworm feeding damage to the ears. Putative resistance findings to fall armyworm were confirmed in the fall armyworm caged feeding experiment expressed by lessened feeding damage to leaves rating on a 1-9 scale 7 to 24 days after infestation. Advanced breeding genotypes confirmed resistant were referred to advance in a breeding program to improve agronomics, and may be used as sources of native resistance.
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