Gut microbiota structure in stingless bees is shaped by ontogeny, caste, and sex

Abstract The gut microbiota of eusocial bees functions as a dynamic system; however, despite extensive study in honey bees and bumble bees, it remains poorly understood in stingless bees. We used 16 S rRNA gene sequencing to characterize the gut microbiota of Melipona capixaba and Melipona mondury across developmental stages (larvae, nurses, and foragers), and across castes (workers and queens) and sexes (males and females) in M. mondury . We found that workers and males harbour richer communities. Workers are dominated by core bee-associated taxa, including Lactobacillus , Bifidobacterium , and Commensalibacter ; whereas males are enriched in transient and environmental genera such as Erwinia and Morganella . Nurse microbiota profile overlaps those of larvae, queens, and foragers. Larvae and queens harbour less diverse communities dominated by fermentative taxa. Both virgin and physogastric queens are dominated by Erysipelatoclostridium sp., indicating notable similarity regardless of physiological status. Predictive functional profiling is consistent with a model where worker and male microbiota are specialized for environmental resilience and oxidative metabolism, while larvae and queens are biased towards fermentation and detoxification. Our findings reveal that the microbiotas of M. capixaba and M. mondury constitute a highly plastic system, providing insights into how social structure interacts to calibrate the microbiota profile of individual colony members.