Soil legacy of SiO₂ nanoparticles impedes fall armyworm oviposition by reprogramming constitutive maize volatiles

Host-plant selection for oviposition strongly influences herbivorous insect population establishment and crop damage, and is largely mediated by plant volatile cues. Silicon dioxide nanoparticles (SiO₂NPs) can modify plant-insect interactions, but whether their effects persist across crop generations through soil-mediated legacy effects remains unknown. Here, we investigated whether foliar SiO₂NP application generates a soil legacy that reprograms maize volatiles and alters the host-plant preference in the fall armyworm (Spodoptera frugiperda).

Maize grown in SiO₂NP-conditioned soil showed no significant changes in early growth traits or silicon (Si) accumulation, but received fewer eggs under field and laboratory conditions. Adult and larval choice assays confirmed reduced S. frugiperda host-plant preference. Soil sterilization eliminated this effect, whereas microbial reintroduction rescued the phenotype, indicating that soil microorganisms contribute to the SiO₂NP legacy effect. Volatile profiling revealed substantial reprogramming of maize volatile blends, including increased emissions of hexanal, (Z)-β-ionone, dihydroactinidiolide (DAL), 6,10,14-trimethyl-2-pentadecanone (phytone), and (3E,7E)-4,8,12-trimethyltrideca-1,3,7,11-tetraene (TMTT). Hexanal, DAL, and TMTT exhibited concentration-dependent behavioral effects, shifting from attraction at control-level emissions to repellence at the elevated levels found in SiO₂NP-conditioned plants.

These results demonstrate that foliar SiO₂NP application induces a soil legacy effect that disrupts S. frugiperda oviposition by quantitatively reprogramming of maize volatiles, without detectable effects on plant growth. This study reveals a previously unrecognized nano-Si-mediated soil feedback mechanism and provides a basis for developing SiO₂NP-based approaches to suppress pest colonization. © 2026 Society of Chemical Industry.