Efficacy of Transgenic Maize LD05 Against Fall Armyworm (Spodoptera frugiperda)

The fall armyworm (<i>Spodoptera frugiperda</i> (J.E. Smith)), which invaded China in 2018, has caused severe corn yield losses and increased pesticide application frequency. <i>Bacillus thuringiensis</i> (Bt)-based genetically modified corn represents an environmentally friendly and effective strategy for managing <i>S. frugiperda</i>. The transgenic corn LD05 harbors the <i>m2cryAb-vip3A</i> insect-resistant fusion gene, which has demonstrated potent inhibitory effects against fall armyworm and is currently in the phase of applying for safety certification. Here, we evaluated the inhibitory efficacy of LD05 against <i>S. frugiperda</i> through laboratory and field experiments during 2022-2024. The LC₅₀ and LC₉₅ of M2CryAb-VIP3A against fall armyworm were 0.024 μg/cm² and 0.508 μg/cm², respectively; and the GLC₅₀ and GLC₉₅ were 0.142 μg cm^-2 and 0.556 μg cm^-2, respectively. M2CryAb-VIP3A expression of LD05 varied significantly across tissues, and remained stable between generations. Bioassays revealed significant tissue-specific differences in fall armyworm larval mortality for LD05 corn tissues, ranked as V5-stage leaves > R3-stage kernels > R1-stage silks. Field trials demonstrated that LD05 corn significantly reduced fall armyworm larval populations, leaf damage incidence, and plant damage incidence compared to non-Bt control Zheng58. Agronomic trait analysis showed no significant differences between LD05 and Zheng58. These results indicate that LD05 has a significant inhibitory effect on fall armyworm, which is an effective strategy for the comprehensive management of fall armyworm in China.