Nutritional Imbalance Reshapes the Body Metabolome of Worker Honey Bees (Apis mellifera): Direction-Specific Changes in Amino-Acid and Lipid Metabolism

Honey bee (Apis mellifera) worker physiology depends on the balance between nectar-derived carbohydrates and pollen-derived nutrients, yet the molecular consequences of nutritional imbalance at the body-compartment level remain incompletely characterized. To address this gap, we profiled the body metabolome (thorax + abdomen) of workers maintained for seven days on one of three defined diets, a combined reference diet (BS; bee bread + sucrose), a bee-bread-only diet (B), or a sucrose-only diet (S), using untargeted UPLC-QTOF/MS. The resulting dataset of 534 putatively annotated metabolites was organized into four direction categories (Both UP, Both DOWN, S↑/B↓, S↓/B↑) relative to BS. Pathway analysis against KEGG identified tryptophan metabolism and ascorbate and aldarate metabolism as the most reproducibly diet-responsive top-ranked modules, the former under sucrose-only feeding and the latter under both nutritional imbalances, with sucrose-only feeding associated with coordinated remodeling of nucleotide-, glycan-, and amino-acid-related metabolism, and bee-bread-only feeding associated with convergent depletion of ascorbate and aldarate metabolism. Five tryptophan-catabolism anchors (L-tryptophan, kynurenine, kynurenic acid, anthranilate, indole-3-acetic acid) were distributed across three of the four direction categories, revealing a branch-specific reorganization in which the kynurenine arm emerged as an S-dominant module and indole-3-acetic acid as a shared depletion marker. These direction-specific metabolite blocks provide compound-level candidate biomarkers of nutritional imbalance in the adult worker body.