Microbial gut diversity of Africanized and European honey bee larval instars

Authors: VOJVODIC, SVJETLANA - University Of Arizona; REHAN, SANDRA - University Of Pennsylvania; Anderson, Kirk

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/5/2013
Publication Date: 8/21/2013
Citation: Vojvodic, S., Rehan, S., Anderson, K.E. 2013. Microbial gut diversity of Africanized and European honey bee larval instars. PLoS One. 8(8):e72106.

Interpretive Summary: The first step in understanding gut microbial ecology is determining the "who and where" of associated microbes. While the core gut bacteria of adult honey bees is becoming increasingly apparent, there is very little and inconsistent information concerning typically present bacterial communities in honey bee larvae. The larval gut is the target of highly pathogenic bacteria and fungi, highlighting the need to understand interactions between typical larval gut flora, nutrition and disease progression. Here we show that the larval gut contained a handful of bacterial groups previously described from adult honey bees or other pollinators. We found both core and environmentally transmitted bacteria with putatively beneficial functions. First and second larval instars contained almost exclusively acetic acid bacteria, while later instars were dominated by one of two very different Lactobacillus spp., depending on the sampled site. Royal jelly inhibition assays revealed that of seven bacteria occurring in larvae, only one was inhibited, four were unaffected, and two were enhanced. Our results suggest that early inoculation by acetic acid bacteria may be important for moderating microbial communities in larvae. This assay is a starting point for more refined research of nutrition and disease resistance in honey bee larvae.

Technical Abstract: The first step in understanding gut microbial ecology is determining the presence and potential niche breadth of associated microbes. While the core gut bacteria of adult honey bees is becoming increasingly apparent, there is very little and inconsistent information concerning symbiotic bacterial communities in honey bee larvae. The larval gut is the target of highly pathogenic bacteria and fungi, highlighting the need to understand interactions between typical larval gut flora, nutrition and disease progression. Here we show that the larval gut contained a handful of bacterial groups previously described from adult honey bees or other pollinators. We found both core and environmentally vectored bacteria with putatively beneficial functions. First and second larval instars contained almost exclusively Alpha 2.2, a core Acetobacteraceae, while later instars were dominated by one of two very different Lactobacillus spp., depending on the sampled site. Royal jelly inhibition assays revealed that of seven bacteria occurring in larvae, only one was inhibited, four were unaffected, and two were enhanced. Our results suggest that early inoculation by Acetobacteraceae may be important for microbial succession in larvae. This assay is a starting point for more sophisticated in vitro models of nutrition and disease resistance in honey bee larvae.