Life on Earth: the diversity of bees is vital for the health of ecosystems

Scientists assessing the level of bee species diversity needed to sustain wild plant populations have concluded that ecosystems depend on many bee species to thrive, not just a few dominant ones.

The report, published in The Proceedings of the Royal Society B, supports the fundamental idea that biodiversity is essential for sustaining life on Earth, especially at a time when species are rapidly disappearing due to the pressures of climate change and development. human.

Dylan Simpson, author and doctoral student in Rutgers Ecology and Evolution graduate program, said, “This is one of the strongest demonstrations to date of the importance of the diversity of bees and rare bee species for the maintenance of healthy ecosystems.

“It’s important because pollination is essential for plant reproduction. And life on earth ultimately depends on plants.

The researchers conducted their investigation by analyzing data from extensive field surveys recording bees visiting flowers in 10 wilderness settings and an experimental garden of native plant species in New Jersey.

A bee pollinates a flower on a Lamb’s Ear plant on May 16, 2021 in San Anselmo, California. (Photo by Justin Sullivan/Getty Images)

In the surveys, the researchers directly observed bee-plant interactions, identified the bee species and flower species visited, and tracked the frequency of interactions between specific bee and plant species.

There are about 400 species of bees in New Jersey alone – some familiar, like the common eastern bumblebee (Bombus impatiens), but others rarely seen.

Simpson said: “There are a lot more bees than you think.

“Many are small, some are metallic and shiny, some are dark, unscratched and inconspicuous.”

While the sightings were all made in open grassland habitats, the bee species observed included those associated with both forests and human-dominated habitats. Plants pollinated included some of the following: Black-eyed Susan (Rudbeckia hirta); lemon balm (Monarda fistulosa); different species of goldenrod (in the genus Solidago); New England Aster (Symphyotrichum novae-angliae); milkweed species (of the genus Asclepias); and common weeds, such as white clover (Trifolium repens) and red clover (T. pratense).

Researchers were trying to establish how many species of bees are needed to pollinate distinct segments of nature. Using this as a framework for investigation, they also wanted to understand the function of rare species in this landscape.

A bumblebee sucks nectar from a flower on May 17, 2019 in Berlin, Germany. May 20 is World Bee Day, which is attracting more attention this year than in previous years due to the significant and continuing decline in bee populations in industrialized countries around the world. (Photo by Sean Gallup/Getty Images)

Simpson continued, “There is a moral and ethical imperative to try to manage ecosystems to keep communities as they are, so they don’t disappear.

“But there’s also the practical argument to be made to come to a better understanding – much of our food comes from animal-pollinated crops.”

Based on their analysis of the data, the authors found that different bee species are often important to different plant species. Accordingly, while only a few bee species are important for a particular plant species, the number of bee species needed to support a large plant community must be equally large.

A significant portion of the bees that pollinated plants were rare species and much previous research has generally focused on single-species crops and concluded that pollination often depends on a few common bees.

Simpson said: ‘In contrast, this study focused on a much wider variety of plants and found that even rare bees can be important for particular plants.

“These findings suggest that ecologists have likely underestimated the importance of bee diversity for pollination in various natural ecosystems.”

Other authors on the paper include: Rachael Winfree, a professor in the Rutgers Department of Ecology, Evolution and Natural Resources; Lucia Weinman, Michael Roswell, and Molly McLeod, all from Rutgers’ graduate program in ecology and evolution; and Mark Genung of the University of Louisiana at Lafayette.

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