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Microbial Co-Occurrence in Floral Nectar Affects Metabolites and Attractiveness to a Generalist Pollinator


Microbial metabolism can shape cues important for animal attraction in service-resource mutualisms. Resources are frequently colonized by microbial communities, but experimental assessment of animal-microbial interactions often focus on microbial monocultures. Such an approach likely fails to predict effects of microbial assemblages, as microbe-microbe interactions may affect in a non-additive manner microbial metabolism and resulting chemosensory cues. Here, we compared effects of microbial mono- and cocultures on growth of constituent microbes, volatile metabolite production, sugar catabolism, and effects on pollinator foraging across two nectar environments that differed in sugar concentration. Growth in co-culture decreased the abundance of the yeast Metschnikowia reukaufii, but not the bacterium Asaia astilbes. Volatile emissions differed significantly between microbial treatments and with nectar concentration, while sugar concentration was relatively similar among mono- and cocultures. Coculture volatile emission closely resembled an additive combination of monoculture volatiles. Despite differences in microbial growth and chemosensory cues, honey bee feeding did not differ between microbial monocultures and assemblages. Taken together, our results suggest that in some cases, chemical and ecological effects of microbial assemblages are largely predictable from those of component species, but caution that more work is necessary to predict under what circumstances non-additive effects are important.

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We thank M. Anderson, M. Handy, and I. Maalouf for laboratory and field assistance. This research was supported by USDA-ARS Research Project 6036-22000-028 (JB and CR), and 2016 ARS Administrator Research Associate program (CR). RS acknowledges support from a USDA NIFA Education and Literacy Initiative Postdoctoral Fellowship (2017-67012-26104). RV was supported by the National Science Foundation (award numbers DEB1846266 and DEB1929516), USDA Multistate award NE1501, the Hellman Foundation and the University of California, Davis.

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Correspondence to Caitlin C. Rering.

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Rering, C.C., Vannette, R.L., Schaeffer, R.N. et al. Microbial Co-Occurrence in Floral Nectar Affects Metabolites and Attractiveness to a Generalist Pollinator. J Chem Ecol 46, 659–667 (2020).

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  • Apis mellifera
  • Olfaction
  • Gustation
  • Nectar microbes
  • MVOC
  • Pollination
  • Volatile organic compounds
  • Phytobiome