Longitudinal effects of supplemental forage on the honey bee (Apis 1 mellifera) microbiota and inter- and intra-colony variability

Authors: ROTHMAN, JASON - University Of California; Carroll, Mark; Meikle, William; Anderson, Kirk; MCFREDERICK, QUINN - Dominican University Of California

Submitted to: Microbial Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/18/2018
Publication Date: 2/3/2018
Citation: Rothman, J.A., Carroll, M.J., Meikle, W.G., Anderson, K.E., Mcfrederick, Q.S. 2018. Longitudinal effects of supplemental forage on the honey bee (Apis 1 mellifera) microbiota and inter- and intra-colony variability. Microbial Ecology. https://doi.org/10.1007%2Fs00248-018-1151-y.
DOI: https://doi.org/10.1007%2Fs00248-018-1151-y

Interpretive Summary: Honey bee colonies obtain much of their gut bacteria (gut microbiota) from fresh nectar and pollen collected from flowering plants (forage). Honey bee colonies often go for long periods of time without fresh forage during winter and early spring. We examined the effects of mid-winter supplemental forage (flowering plants planted as bee forage sources) on worker bee gut microbiota. Overwintering honey bee colonies were either given access (forage-supplemented) or not given access (unsupplemented) to flowering plants for one month before February almond pollination. Worker bees were sampled four times from colonies from December 2015 to April 2016. The bacteria present in worker guts were identified and quantified by gene sequencing. The bacteria present in the gut microbiota did not change much over the winter and early spring. Workers from forage-supplemented and unsupplemented colonies had similar gut microbiota in all but one month. In March, workers from supplemented colonies had proportionally more of the gut bacteria Gilliamella apicola, Lactobacillus, and Bartonella than workers from unsupplemented colonies. Surprisingly, individual workers from the same colony varied as much in their gut microbiota as individual workers from different colonies. These results show that the gut microbiota of worker bees remains stable and consistent over winter and early spring. This study also shows that winter forage can change the relative abundance, but not the species present, of gut bacteria present in overwintering worker bees. This study shows that honey bees do not require fresh mid-winter forage to maintain healthy worker gut microbiota through the winter.

Technical Abstract: Honey bee colonies obtain much of their gut bacteria (gut microbiota) from fresh nectar and pollen collected from flowering plants (forage). Honey bee colonies often go for long periods of time without fresh forage during winter and early spring. We examined the effects of mid-winter supplemental forage (flowering plants planted as bee forage sources) on worker bee gut microbiota. Overwintering honey bee colonies were either given access (forage-supplemented) or not given access (unsupplemented) to the flowering mustard plant rapini for one month before February almond pollination. Worker bees were sampled four times from colonies from December 2015 to April 2016. The bacteria present in worker guts were identified and quantified by gene sequencing. The bacteria species composition present in the gut microbiota did not change much over the winter and early spring. Workers from forage-supplemented and unsupplemented colonies had similar gut microbiota in all but one month. In March, workers from supplemented colonies had proportionally more of the gut bacteria Gilliamella apicola, Lactobacillus, and Bartonella than workers from unsupplemented colonies. Surprisingly, individual workers from the same colony varied as much in their gut microbiota as individual workers from different colonies. These results show that the gut microbiota of worker bees remains stable and consistent over winter and early spring. This study also shows that winter forage can change the relative abundance, but not the species present, of gut bacteria present in overwintering worker bees. This study shows that honey bees do not require access to fresh mid-winter forage to maintain healthy worker gut microbiota through the winter.