Discovery of farnesal from a wild cucumber landrace enables eco-compatible biopesticide development against aphids

Pest infestations devastate crop production, but chemical pesticides pose environmental and health risks. Eco-friendly biopesticides offer a solution, though limited by bioactive compound discovery. Here, we demonstrate that utilization of Yunnan's Xishuangbanna-a cucumber diversity hotspot-to identify the local variety XSBN032, which retains desirable agronomic traits under aphid pressure. Metabolomic and GC-MS analyses identify farnesal-a volatile compound significantly enriched in XSBN032-under infested and non-infested conditions. Applying 0.33 g/L farnesal nanoemulsion to cucumber leaves rapidly disrupts aphid metabolism (within 6 h), impairing amino acid pathways and suppressing growth/reproduction, achieving 74.9% mortality within 24 h while preserving plant photosynthesis. Significantly, this treatment demonstrates high environmental safety: 0% earthworm mortality (500 mg/L, 7 days) and negligible effects on natural enemies (0% ladybird mortality; 7.41% green lacewing mortality). Our study establishes an integrated pipeline-from resistant germplasm discovery to biopesticide development-providing a sustainable pest control strategy. Leveraging multi-omics screening and smart delivery systems holds promise for future eco-efficient biopesticides.