Comparative analysis of gut symbionts in (Coleoptera: Tenebrionidae) and their dietary substrate, sauce-flavored Daqu.

(red flour beetle), a major pest infesting stored sauce-flavored Daqu (SFD), causes significant economic losses in the sauce-flavored liquor industry. This study analyzed microbial interactions between SFD and (adults and larvae) using 16S rDNA and ITS sequencing. guts primarily hosted Bacteroidota (44.7% adults, 50.9% larvae) and Proteobacteria, contrasting SFD's Firmicutes-dominated community (89.3%), featuring (31.7%) and (11.2%). Fungal communities across groups were Ascomycota-rich (90%), with (86%) as core, while larvae uniquely harbored (5.5%). Larvae shared more bacterial taxa with SFD (5 genera vs. 3 in adults), yet high-abundance SFD bacteria (e.g., ) were scarce in guts (0.6%) and vice versa. Fungal source tracking revealed SFD contributed 89-94% of gut fungi, vastly exceeding bacterial inputs (2.8-5%). Shared bacterial ASVs (n=58) exhibited functional divergence: carbohydrate metabolism dominated in SFD, whereas insect-associated ASVs enriched drug resistance genes. Findings suggest selectively colonizes SFD bacteria (e.g., , ) while proportionally acquiring fungi (e.g., ) via dietary transmission. These microbes may act as a gut "seed bank" or host-selected symbionts, warranting further validation to clarify their ecological roles and inform microbially-based pest control strategies.