Microbial ecology of the hive and pollination landscape: bacterial associates from floral nectar, the alimentary tract and stored food of honey bees (Apis mellifera)

PLoS One. 2013 Dec 17;8(12):e83125. doi: 10.1371/journal.pone.0083125. eCollection 2013.

Abstract

Nearly all eukaryotes are host to beneficial or benign bacteria in their gut lumen, either vertically inherited, or acquired from the environment. While bacteria core to the honey bee gut are becoming evident, the influence of the hive and pollination environment on honey bee microbial health is largely unexplored. Here we compare bacteria from floral nectar in the immediate pollination environment, different segments of the honey bee (Apis mellifera) alimentary tract, and food stored in the hive (honey and packed pollen or "beebread"). We used cultivation and sequencing to explore bacterial communities in all sample types, coupled with culture-independent analysis of beebread. We compare our results from the alimentary tract with both culture-dependent and culture-independent analyses from previous studies. Culturing the foregut (crop), midgut and hindgut with standard media produced many identical or highly similar 16S rDNA sequences found with 16S rDNA clone libraries and next generation sequencing of 16S rDNA amplicons. Despite extensive culturing with identical media, our results do not support the core crop bacterial community hypothesized by recent studies. We cultured a wide variety of bacterial strains from 6 of 7 phylogenetic groups considered core to the honey bee hindgut. Our results reveal that many bacteria prevalent in beebread and the crop are also found in floral nectar, suggesting frequent horizontal transmission. From beebread we uncovered a variety of bacterial phylotypes, including many possible pathogens and food spoilage organisms, and potentially beneficial bacteria including Lactobacillus kunkeei, Acetobacteraceae and many different groups of Actinobacteria. Contributions of these bacteria to colony health may include general hygiene, fungal and pathogen inhibition and beebread preservation. Our results are important for understanding the contribution to pollinator health of both environmentally vectored and core microbiota, and the identification of factors that may affect bacterial detection and transmission, colony food storage and disease susceptibility.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Bacteria / isolation & purification*
  • Bacteriological Techniques
  • Bees / microbiology*
  • Bees / physiology*
  • DNA, Bacterial / genetics
  • Ecology
  • Endophytes / isolation & purification
  • Gastrointestinal Tract / microbiology*
  • Honey / microbiology*
  • Plant Nectar
  • Pollination*
  • RNA, Ribosomal, 16S / genetics
  • Symbiosis

Substances

  • DNA, Bacterial
  • Plant Nectar
  • RNA, Ribosomal, 16S

Grant support

Funding was provided entirely by the USA tax-payer supported operating budget of the Agricultural Research Service-U.S. Department of Agriculture Carl Hayden Bee Research Center, Tucson AZ. There were no current external funding sources for this study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.