Silicon fertilization in maize increases attractiveness of nocturnal herbivore-induced plant volatiles to Spodoptera frugiperda natural enemies.

Background: Silicon (Si) fertilization has been well-documented to enhance plant resistance against insect pests by increasing the abrasiveness and toughness of leaf tissues. Additionally, Si also interacts with the jasmonic acid pathway, which modulates antiherbivore induced defenses, including the emission of herbivore-induced plant volatiles (HIPVs) that attract natural enemies. In this study, we examined the influence of Si fertilization on the attractiveness of nocturnal HIPVs from maize plants infested with the fall armyworm (FAW), Spodoptera frugiperda (JE Smith), to the predatory earwig Doru luteipes (Scudder).

Results: In laboratory assays, we found that Si fertilization did not alter the attractiveness of nocturnal constitutive volatiles to the nocturnal predator D. luteipes. However, upon infestation with FAW larvae, Si-fertilized plants emitted a volatile blend that was more attractive to D. luteipes. Although the composition of HIPVs emitted by non-fertilized and Si-fertilized plants was similar, the terpene neryl acetate was exclusively detected in the HIPV blend from Si-fertilized plants. Tests with synthetic neryl acetate demonstrated that the terpene alone was attractive to the earwig at the specific concentration found in the HIPV blend emitted by Si-fertilized plants.

Conclusion: This study demonstrates that Si fertilization primes indirect defenses by specifically increasing the amount of neryl acetate in the HIPV blend, which is responsible for the enhanced attractiveness to the predatory earwig. Thus, Si can act as a priming agent of indirect plant defenses, potentially increasing the recruitment of the predatory earwig once plants are infested by FAW, thereby contributing to suppress insect pest populations. © 2025 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.