Distinct colony niches shape associated microbiotas in Neotropical stingless bees.

Stingless bees (Meliponini) are an ancient lineage of eusocial insects whose associated microbiomes have been increasingly studied in comparison with those of honey bees. In this review, I synthesize current evidence on microbial communities associated with stingless bees across life stages and colony compartments, emphasizing how patterns of host association differ among distinct biological contexts. I propose that stingless bee microbiomes are not uniformly more environmentally driven than those of honey bees. Instead, strong and evolutionarily conserved filters structure microbial communities associated with larvae and adult guts, whereas greater environmental input is more evident in some colony resources, such as stored food and nest materials. Comparative analyses further indicate that differences between honey bees and stingless bees arise primarily from lineage-specific elaborations in colony biology that created new ecological opportunities for microbial diversification, rather than from fundamental divergence in gut-associated microbiota. Framing stingless bee colonies within a modular framework-where larvae, adult guts, and colony resources represent distinct microbial arenas-provides a coherent way to integrate these contrasting dynamics and to understand how host-microbe associations are maintained, reorganized, and evolve in eusocial systems viewed as modular holobionts.