Early Detection of Volatile Biomarkers in Wheat Grain Induced by Sitophilus oryzae Using Static Headspace Gas Chromatography Mass Spectrometry

The rice weevil, Sitophilus oryzae (L.), is one of the most destructive pests of stored cereals, responsible for substantial qualitative and quantitative losses during wheat storage. Early detection is important in reducing grain losses. This study used static headspace – gas chromatography mass spectrometry (HS-GC-MS) to examine changes in volatile compounds between uninfested and S. oryzae-infested wheat grain under different insect densities. A total of 48 volatile compounds associated with insect infestation were identified, mainly including aldehydes, alcohols, furans, sulfur-containing compounds, hydrocarbons, and terpenoids. Differential analysis screened 12 characteristic volatile compounds with potential indicator significance, showing clear gradient variation trends under different insect infestation levels. Variable importance in projection (VIP) analysis identified several key volatile biomarkers, among which furan, 2-pentyl, hexanal, dimethyl disulfide, and isoborneol contributed significantly to infestation level discrimination. The study demonstrates that insect infestation synergistically influences wheat volatile metabolite composition through multiple metabolic pathways, including lipid oxidation metabolism, sulfur-containing degradation metabolism, and insect-derived volatile contributions, thereby forming an insect density-dependent volatile metabolic fingerprint.