Gut microbiota of BrazilianMeliponastingless bees: dominant members and their localization in different gut regions

The gut microbiome of eusocial corbiculate bees, which include honeybees, bumblebees, and stingless bees, consists of anciently associated, host-specific bacteria that are vital for bee health. Two symbionts,SnodgrassellaandGilliamella, are ubiquitous in honeybees and bumblebees. However, their presence varies in the stingless bee clade (Meliponini), a group with pantropical distribution. They are absent or rare in the diverse genusMelipona, indicating a shift in microbiota composition in this lineage. To identify the main members of theMeliponamicrobiota, we combined newly collected and published data from field-collected individuals of several species. Additionally, we identified the localization of the dominant microbiota members within the gut regions ofMelipona quadrifasciata anthidioides. The dominant microbiota ofMeliponaspecies includes members of the generaBifidobacterium, Lactobacillus, Apilactobacillus, Floricoccus, andBombella. Among these,ApilactobacillusandBombelladominate in the crop, whereasApilactobacillusand other members of the Lactobacillaceae dominate the ventriculus. The ileum lacksSnodgrassellaorGilliamellabut contains a putative new symbiont close toFloricoccus, as well as strains ofBifidobacterium, Lactobacillaceae (includingApilactobacillus), andBombella. The rectum is dominated byBifidobacteriumandLactobacillus. In summary, theMeliponamicrobiota is compositionally distinct but shows spatial organization paralleling that of other eusocial corbiculate bees.