Integrated metabolomic and proteomic profiling reveals density-dependent variation in development and chemical composition of queen bee larvae

Abstract

Queen bee larvae (QBL), a byproduct of royal jelly production, are gaining prominence as a functional food due to their health-promoting effects. Beekeepers routinely adjust queen cell numbers per colony to maximize the yield of royal jelly during commercial production, yet the impact of rearing density on developmental and chemical properties of QBL remains unclear. This study compared the body weight, metabolome, and proteome of QBL reared with one versus five queen cell strips (64 cells per strip) in honeybee colonies. Larval weight was significantly lower in 5-strip colonies compared to 1-strip colonies, suggesting a developmental delay in response to increased rearing density. Metabolomic profiling revealed that 1-strip QBL contained higher levels of antioxidants and vitamins, whereas 5-strip QBL exhibited stress-related metabolic shift, including uric acid and kynurenine accumulation. Proteomic analysis identified seven major royal jelly proteins (MRJPs), accounting for 27.20% of the proteome, with MRJP2 being the most abundant, followed by MRJP3 and MRJP1. Between the two QBL groups, significant differences were detected in low-abundance proteins rather than in the MRJPs. These compositional differences, however, did not translate into significant variations in overall antioxidant activity. This study provides the first integrated metabolomic and proteomic characterization of QBL, supporting their potential as a functional food. The findings demonstrate that increasing rearing density elevates the total yield per colony, but at the cost of reduced larval weight and compromised nutritional quality. Therefore, rearing density is established as a critical factor determining the developmental and chemical properties of QBL, offering key insights for optimizing production practices.