Nitrogen‐Mediated Remodelling of <i>Lycium Barbarum</i> Leaf Traits Drives Multimodal Host Selection by <i>Bactericera Gobica</i>

In commercial Lycium barbarum production, excessive nitrogen (N) input is associated with outbreaks of the wolfberry psyllid (Bactericera gobica), yet the mechanisms underlying nitrogen-driven population increases remain unclear. Integrating field surveys, pot experiments, behavioural assays, and multi-omics analyses, we show that N supply links shifts in visual/olfactory cues and phloem nutrition to B. gobica population increase. Across nine plantations in three major production regions, infestation severity increased significantly with nitrogen input. High N (HN) reprogrammed chloroplast and carotenoid pathways, producing deeper leaf greenness and elevated apocarotenoids (α-ionone, (E)-β-ionone, and benzeneacetaldehyde) that increased pre-landing encounters and attraction. Concurrently, HN elevated leaf soluble sugars and improved phloem nutritional quality, enhancing post-landing acceptance and feeding. Demographic assays revealed higher oviposition, nymphal abundance, and adult densities on HN plants. Thus, an HN-induced trait suite-enhanced visual/olfactory cues coupled with superior phloem nutrition-promotes host encounter and fecundity, delineating a multimodal bottom-up pathway from fertilisation to outbreak risk. These results provide a mechanistic rationale for optimising N inputs in L. barbarum production and motivate integrating nutrient management with semiochemical- and vision-based monitoring and trapping to reduce pest pressure.