Analysis of Multiple Tsetse Fly Populations in Uganda Reveals Limited Diversity and Species-Specific Gut Microbiota
ABSTRACTThe invertebrate microbiome contributes to multiple aspects of host physiology, including nutrient supplementation and immune maturation processes. We identified and compared gut microbial abundance and diversity in natural tsetse flies from Uganda using five genetically distinct populations ofGlossina fuscipes fuscipesand multiple tsetse species (Glossina morsitans morsitans,G. f. fuscipes, andGlossina pallidipes) that occur in sympatry in one location. We used multiple approaches, including deep sequencing of the V4 hypervariable region of the 16S rRNA gene, 16S rRNA gene clone libraries, and bacterium-specific quantitative PCR (qPCR), to investigate the levels and patterns of gut microbial diversity from a total of 151 individuals. Our results show extremely limited diversity in field flies of different tsetse species. The obligate endosymbiontWigglesworthiadominated all samples (>99%), but we also observed wide prevalence of low-densitySodalis(tsetse's commensal endosymbiont) infections (<0.05%). There were also several individuals (22%) with highSodalisdensity, which also carried coinfections withSerratia. Albeit in low density, we noted differences in microbiota composition among the genetically distinctG. f. fuscipesflies and between different sympatric species. Interestingly,Wigglesworthiadensity varied in different species (104to 106normalized genomes), withG. f. fuscipeshaving the highest levels. We describe the factors that may be responsible for the reduced diversity of tsetse's gut microbiota compared to those of other insects. Additionally, we discuss the implications ofWigglesworthiaandSodalisdensity variations as they relate to trypanosome transmission dynamics and vector competence variations associated with different tsetse species.