Conserved gut microbiomes with cross-species spillover between sympatric Neotropical stingless bees and honey bees

). These patterns indicate that human-mediated management practices, such as mixed apiaries and artificial feeding, create ecological opportunities for interspecific microbial exchange. Overall, our results show that stingless bee gut microbiomes are compositionally stable yet ecologically permeable, shaped jointly by long-term host specificity and recent anthropogenic contact.IMPORTANCEStingless bees are key pollinators in tropical ecosystems and hold long-standing cultural significance in the Neotropics; however, their microbiomes remain far less studied than those of managed honey bees. Understanding how gut bacterial communities vary across landscapes, and whether microbes move between native and non-native hosts, is essential for predicting the ecological consequences of increasing meliponiculture and urban beekeeping. Our study reveals that stingless bee gut microbiota are generally stable and host-associated but nonetheless acquire bacterial symbionts typical of honey bees, indicating that human management practices facilitate cross-species microbial transmission. These findings broaden current knowledge of bee-microbe evolution by showing that gut symbiont boundaries are not fixed but can become permeable under anthropogenic influence. This has important implications for pollinator health, conservation, and biosecurity as managed and native bees increasingly co-occur in human-modified environments.