Short communication: The persistent influence of host lineage on the gut microbiomes of black soldier fly and yellow mealworm

Production insects such as the black soldier fly (BSF) and yellow mealworm (YM) are increasingly recognised as sustainable protein sources, and selective breeding of genetically distinct lines offers opportunities to improve production efficiency. However, insect performance is also influenced by the gut microbiome, which provides essential metabolic and protective functions. Despite this, current breeding programmes typically focus on host genetics and phenotypes, assuming that microbiome composition remains stable under consistent rearing conditions. However, this hypothesis remains largely untested. We examined gut bacterial communities in ten distinct BSF and YM populations reared for multiple generations under identical conditions. Each species shared a distinct set of ten zero-radius operational taxonomic units (zOTUs) across all populations, but their relative abundances varied, indicating host-specific effects on microbiome composition. Strain-specific zOTUs also persisted despite uniform environments. These findings suggest that host genetic background exerts a more persistent influence on gut microbiome composition than previously assumed.