According to a new study by a team of researchers, including University of Maryland entomologist Michael Roswell, a meadow’s lush array of flowers need a whole phalanx of bees to pollinate them – far more than bees and bumblebees that most people are familiar with. A postdoctoral associate in the Department of Entomology, Roswell helped demonstrate that less common bees are far more important to ecosystem health than previously documented.
Past research on bees as pollinators has tended to focus on specific plants – often crops – or entire communities of plants as if they were a single entity. This tended to overestimate the contribution of the more common bees, especially since two percent of bee species provided 80 percent of crop pollination. But no previous work had asked the fundamental question: how many species of pollinators are needed to pollinate all species in a given plant community?
Roswell and his colleagues have now shown that the more plant species there are, the more bee species are needed for pollination. They found that less common bees often visited specific plants that others did not visit. Their findings shed new light on the role of rare species in ecosystems, critical to conservation efforts, as rare species are most at risk of extinction due to habitat loss, pollution, climate change and other factors. The study appeared in the Proceedings of the Royal Society B.
“Our work shows that things that are rare in general, like infrequent visitors to a meadow, can still serve very important functions, like pollinating plants that no one else pollinates,” said Roswell, who studies diversity and pollination in UMD’s Department of Entomology and Entomology. is co-author of the study. “And that’s a really good argument for why biodiversity matters.”
The researchers studied 10 plots in New Jersey that included wild meadows and seeded fields for one year. They observed bees of more than 180 species making nearly 22,000 visits to more than 130 different plant species. The team used these encounters to estimate the pollination services that each type of bee provides to each plant, because a plant’s most frequent floral visitors are usually its most important pollinators.
Their analyzes showed that an entire grassland community depended on 2.5 to 7.5 times more bee species for pollination than a single typical plant species. They also found that locally rare species accounted for up to 25% of important pollinator species, and that this number was highest in grasslands with the greatest plant diversity. This suggests that at larger scales like entire ecosystems, the number of locally rare species that are important for pollination is even greater.
“We were looking at grasslands that might be a few acres in size,” Roswell said, “but a typical bee flies a few square miles, which is a really large, complicated landscape filled with many different types of plants that bloom at different times and are visited by different insects.At this scale, even more pollinator diversity is likely to be important.
– This press release originally appeared on the University of Maryland website