Efficacy of Bt‐( Cry1Ab  +  Cry2Ab  +  Cry1Fa ) maize against Spodoptera frugiperda and other lepidopteran migratory pests in tropical Asia

BACKGROUND: The invasive fall armyworm Spodoptera frugiperda and other lepidopteran migratory pests significantly threaten maize production in tropical Asia, a key year-round breeding region and source of spring or summer migrants across the broader Asian region. The strategic deployment of genetically modified maize expressing pyramided Bacillus thuringiensis (Bt) toxins offers a promising approach for managing multiple pests and delaying resistance evolution in this region. This study evaluated the insecticidal efficacy of Bt maize (LP026-2 event, Cry1Ab + Cry2Ab + Cry1Fa) against six major lepidopteran pests: S. frugiperda, Mythimna separata, Spodoptera exigua, Spodoptera litura, Helicoverpa armigera, and Ostrinia furnacalis. RESULTS: ) in kernels. Bioassays demonstrated its high efficacy, with corrected mortality >90% against all six pests in leaf and kernel assays after 5 days. Pest susceptibility ranked as H. armigera > S. frugiperda > O. furnacalis > M. separata > S. exigua > S. litura, with efficacy highest in leaf, followed by kernel and silk tissues (silk mortality 69.15-98.94%). Field trials further validated the efficacy of Bt maize, showing significant reduction in larval densities, plant damage, along with 4.52-25.41% yield increase over the non-Bt maize. CONCLUSION: These findings demonstrate that Bt-(Cry1Ab + Cry2Ab + Cry1Fa) maize provides effective multi-pest control and yield benefits, supporting its integration into the migratory pest management strategies for tropical maize production systems. © 2025 Society of Chemical Industry.