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Summer 2011

Urban Jungle

The changing natural world at our doorsteps | Illustration and text by Patterson Clark      

Rusty-patched Bumblebee, Bombus affinis

Once abundant in the eastern United States, the rusty-patched bumblebee has almost vanished.

July 12, 2011

Plight of the bumblebee

That tomato ripening in your garden probably got its start after a visit from a bumblebee.

Tomatoes, potatoes and other plants in the nightshade family are best fertilized by "buzz pollinators" such as the bumblebee, which will clinch a flower in its jaws and rapidly vibrate its wing muscles to give the blossom a good shake.

This rattles loose pollen that collects on the bee's pile, or hairy coat. The bee will carry most of it back to the hive and pack it with nectar into a brood cell for bee larvae to eat.

Bumblebees are such effective pollinators that they have been raised commercially for use in produce greenhouses — a practice that may have precipitated a rapid decline in some wild bumblebee populations.

Bees sent to Europe for commercial breeding may have returned to the United States with a microsporidian parasite, which could be responsible for decimating several species of bumblebees. Other possible contributing factors: global warming, fragmented habitats, pesticides and a lower genetic diversity in those bumblebee species that are in decline.

Sources: "Patterns of widespread decline in North American bumble bees," Proceedings of the National Academy of Sciences; The Xerces Society for Invertebrate Conservation