The vectoring of Starmerella species and other yeasts by stingless bees in a Neotropical savanna

In Brazilian savannas, stingless bees are associated with yeast communities composed mainly of Starmerella species. This study aimed to establish the distribution of yeasts associated with the bee species Frieseomelitta varia, Scaptotrigona aff. postica, Scaptotrigona polysticta, Tetragonisca angustula angustula, Melipona compressipes manaosensis and Melipona scutellaris in northern savannas and the importance of yeasts in the resource partitioning of bees. We collected 380 bees from six species, which were individually placed in Petri plates containing rich medium for 15 min. Yeasts were then isolated, resulting in the identification of 54 species, 48 of which were ascomycetous, while six were basidiomycetous. Torulaspora delbrueckii was the most frequently isolated yeast species in this study, followed by Pichia membranifaciens, Starmerella apicola, Pichia kluyveri, Starmerella meliponinorum and Starmerella bombicola. The total number of Starmerella species identified showed that these species are prevalent in association with these stingless bees. These communities differ from stingless bee-associated yeasts found in the southern savannas of Brazil. Although stingless bees are generalist foragers, there are some yeasts showing high prevalence in only one bee species, resulting in differences in niche breadth that may point to a role of yeasts in the resource partitioning of bees in Brazilian savannas. (C) 2020 Elsevier Ltd and British Mycological Society. All rights reserved.