Temporal dynamics of plant and fungal communities based on pollen sampled from honey bee hives in Southern Ontario, Canada

Multitrophic interactions are inherent to the ecological networks of terrestrial ecosystems and can exhibit dynamic temporal changes within a season. In floral communities, pollen and nectar act as hubs for various microorganisms, including fungi that can alter plant–pollinator interactions. In mixed pollen samples collected by Apis mellifera L., the associations between plants and fungi foraged by bees may be complex and not yet fully characterized. Exploring the temporal succession of the multitrophic interaction is an area that requires further investigation. Forty-two pollen samples were retrieved from 13 hives dispersed in urban and peri-urban locations in Southern Ontario Canada where the honey bee is not native. Using metabarcoding of the ITS region, we identified a total of 77 plants and 46 fungi. Among the foraged plants visited, the top ten were all non-native or invasive taxa for Southern Ontario, with Trifolium repens L. and Sonchus arvensis L. as most common taxa. For fungal taxa, the main yeasts and molds were identified as Starmerella and Mucor taxa. Plant richness was found to have a significant association with fungal richness. Moreover, plant and fungal taxa richness and Shannon diversity increased with time from spring to late summer. Only plant taxa composition varied over the active foraging season suggesting a more homogenous fungal taxa community. Diverse flowers can further play a role in the spread of fungal organisms having a variety of ecological functions and trophic levels. The study of their interactions with flowers, pollinators, and humans, is deserving of more investigation.