Study reveals important flowering plants for city-dwelling honey bees
By Pennsylvania State University
UNIVERSITY PARK, Pa. — Trees, shrubs and woody vines are among the top food sources for honey bees in urban environments, according to an international team of researchers. By using honey bees housed in rooftop apiaries in Philadelphia, the researchers identified the plant species from which the honey bees collected most of their food, and tracked how these food resources changed from spring to fall. The findings may be useful to homeowners, beekeepers and urban land managers who wish to sustain honey bees and other bee and pollinator species.
“We know that cities can support a surprising diversity of bee species; however, cities are complex environments, and traditional floral surveying methods can be hard to implement,” said Christina Grozinger, distinguished professor of entomology and director of the Center for Pollinator Research, Penn State. “By analyzing the pollen that honey bees brought back to their colonies and how the weights of these colonies changed every hour, we were able to identify the flowering plants that provide the most nutrition for bees in Philadelphia, and understand how these resources change across the seasons.”
The researchers installed 12 apiaries, each containing three honey bee colonies, at locations throughout Philadelphia. Each colony was equipped with a pollen trap for capturing incoming pollen and a scale for logging its weight once per hour. The team visited each apiary monthly to collect pollen samples. They sequenced the DNA from the samples to determine which plant genera were present in each sample. Their findings appeared on April 27 in the journal Ecosphere.
“Ours is the first study to combine two novel techniques — continuous colony weight monitoring and pollen DNA metabarcoding — to answer simultaneously the questions of ‘what’ and ‘how much’ with respect to the flowers that are available to foraging insects,” said Douglas Sponsler, postdoctoral scholar in entomology, Penn State. “Colony weight patterns tell us when resources are plentiful and when they are scarce. Pollen DNA metabarcoding tells us which plants are available at a given time and how the floral community changes through the year.”
Read more in Ecosphere: https://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecs2.3102