Effects of methyl jasmonate seed treatments on adult oviposition preference and larval performance of seed corn maggot (Delia platura) in corn (Zea mays)

BACKGROUND: Eliciting host plant resistance using plant hormones such as jasmonates has the potential to protect seeds and seedlings against insect pests; however, several hurdles exist for adapting it for pest management. This includes determining a dose that promotes resistance without limiting plant growth, an application method that growers could use, and ensuring the plants are responsive in the abiotic conditions when the pest occurs. In laboratory and field assays, we tested if treating corn seeds with multiple concentrations of methyl jasmonate would reduce the preference of ovipositing seed corn maggot adults and the performance of larvae feeding on seeds. RESULTS: We found that corn seeds soaked in aqueous 0.2 mM methyl jasmonate solution showed marginally lower seedling growth, but the adult oviposition preference was similar to 60% lower on these seeds compared to control water-soaked seeds. Seeds that were treated with methyl jasmonate using a conventional polymer-based seed coating showed no effect on seedling growth but reduced adult oviposition preference. In no-choice bioassays with adult flies, we found reduced oviposition on seeds soaked with aqueous methyl jasmonate compared to controls. Larval survival to pupation was also lower in methyl jasmonate-treated seeds. Lastly, the methyl jasmonate-induced resistance also occurred at the lower temperatures typical of the spring soil conditions when this fly is most damaging. CONCLUSION: Methyl jasmonate seed treatment in aqueous solution or using conventional polymer-based technology, has the potential to deter adult oviposition and reduce maggot performance in spring temperature conditions with minor effects on seed germination and growth. (c) 2024 Society of Chemical Industry.