Impact of Nosema Disease and American Foulbrood on Gut Bacterial Communities of Honeybees Apis mellifera.

Honeybees, Apis mellifera, are important pollinators of many economically important crops. However, one of the reasons for their decline is pathogenic infection. Nosema disease and American foulbrood (AFB) disease are the most common bee pathogens that propagate in the gut of honeybees. This study investigated the impact of gut-propagating pathogens, including Nosema ceranae and Paenibacillus larvae, on bacterial communities in the gut of A. mellifera using 454-pyrosequencing. Pyrosequencing results showed that N. ceranae was implicated in the elimination of Serratia and the dramatic increase in Snodgrassella and Bartonella in adult bees' guts, while bacterial communities of P. larvae-infected larvae were not affected by the infection. The results indicated that only N. ceranae had an impact on some core bacteria in the gut of A. mellifera through increasing core gut bacteria, therefore leading to the induction of dysbiosis in the bees' gut.

Bacterial Communities in Three Parts of Intestinal Tracts of Carpenter Bees (Xylocopa tenuiscapa).

This study investigated different bacterial communities in three intestinal parts (foregut, midgut and hindgut) of Xylocopatenuiscapa to understand the roles of gut bacteria. Our phylogenetic analysis revealed that X. tenuiscapa is closely related to Xylocopa latipes. The 16S rRNA gene in the genomic DNA samples from the gut was examined by illumina (Solexa) and a total of 998 operational taxonomic unit (OTUs) clusters were found. Taxonomic classification identified 16 bacterial phyla and unclassified bacteria. The dominant bacteria taxa in the three parts of X. tenuiscapa gut were Proteobacteria, Firmicutes, Bacteroidetes and Actinobacteria. In the foregut, Lactobacillales and Enterobacteriaceae were predominantly found. The population in the midgut was similar to that in the foregut, with the addition of Gilliamella, which was also abundant. The most dominant bacteria identified in the hindgut were similar to those in the midgut and Lactobacillales, Enterobacteriaceae, Gilliamella, Bifidobacteriaceae and Flavobacteriaceae appeared in abundance. Moreover, our results suggest that a community structure of bacteria in different parts of X. tenuiscapa's gut may be an important indicator of carpenter bees' health. This functional study of bacterial communities revealed significant differences among the three intestinal parts and is the first report of the gut bacteria structure in solitary bees.