Influence of Feeding Type and Nosema ceranae Infection on the Gut Microbiota of Apis cerana Workers

The gut microbiota plays an essential role in the health of bees. To elucidate the effect of feed and Nosema ceranae infection on the gut microbiota of honey bee (Apis cerana), we used 16S rRNA sequencing to survey the gut microbiota of honey bee workers fed with sugar water or beebread and inoculated with or without N. ceranae. The gut microbiota of A. cerana is dominated by Serratia, Snodgrassella, and Lactobacillus genera. The overall gut microbiota diversity was show to be significantly differential by feeding type. N. ceranae infection significantly affects the gut microbiota only in bees fed with sugar water. Higher abundances of Lactobacillus, Gluconacetobacter, and Snodgrassella and lower abundances of Serratia were found in bees fed with beebread than in those fed with sugar water. N. ceranae infection led to a higher abundance of Snodgrassella and a lower abundance of Serratia in sugar-fed bees. Imputed bacterial Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways showed the significant metagenomics functional differences by feeding and N. ceranae infections. Furthermore, A. cerana workers fed with sugar water showed lower N. ceranae spore loads but higher mortality than those fed with beebread. The cumulative mortality was strongly positive correlated (rho = 0.61) with the changes of overall microbiota dissimilarities by N. ceranae infection. Both feeding types and N. ceranae infection significantly affect the gut microbiota in A. cerana workers. Beebread not only provides better nutrition but also helps establish a more stable gut microbiota and therefore protects bees in response to N. ceranae infection. IMPORTANCE The gut microbiota plays an essential role in the health of bees. Scientific evidence suggests that diet and infection can affect the gut microbiota and modulate the health of the gut; however, the interplay between those two factors and the bee gut microbiota is not well known. In this study, we used a high-throughput sequencing method to monitor the changes of gut microbiota associated with both feeding types and Nosema ceranae infection. Our results showed that the gut microbiota composition and diversity of Asian honey bee were significantly associated with both feeding types and the N. ceranae infection. More interestingly, bees fed with beebread showed higher microbiota stability and lower mortality rates than those fed with sugar water when infected by N. ceranae. Those data suggest that beebread has the potential not only to provide better nutrition but also help to establish a more stable gut microbiota to protect bees against N. ceranae infection.