[Pollinator] The mysterious reappearance of the white-bottomed bee

Mon Oct 14 14:35:55 PDT 2013

<https://www.hcn.org/issues/45.17/the-mysterious-reappearance-of-the-white-b
ottomed-bee>
https://www.hcn.org/issues/45.17/the-mysterious-reappearance-of-the-white-bo
ttomed-bee

High Country News - For People who care about the West.

The mysterious reappearance of the white-bottomed bee

A Western species that crashed in the 1990s may be making a comeback in
Washington and Colorado.

NEWS - From the  <https://www.hcn.org/issues/45.17> October 14, 2013 issue
<https://www.hcn.org/author_search?getAuthor=Michelle%20Nijhuis&sort_on=Publ
icationDate&sort_order=descending> By Michelle Nijhuis

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cid:image003.jpg at 01CEC8DF.5E952D20

On a recent Saturday afternoon in a quiet suburb north of Seattle, Wash.,
Will Peterman leaned into a thick hedge of blackberry bushes, looking for a
lost species. The hedge buzzed with bees of every description -- in a single
glance, Peterman counted six species -- but two plump, slow-moving
bumblebees, each about the size of a small grape, captured his attention.

"There's one," he said quietly. "And there's another one."

They were Western bumblebees, a native species. Bombus occidentalis was once
among the most common bumblebees in the Western United States. In the late
1990s, its populations crashed, and the species all but disappeared from
about a quarter of its historic range. Despite regular surveys of the
Seattle area by researchers and volunteers, no sighting was confirmed for
well over a decade. Then, in early July, Peterman confirmed a 2012 sighting
in this neighborhood.

In early September, biologists from the University of Colorado at Boulder
announced that Western bumblebees had also returned to Colorado's Front
Range, with more than 20 individuals observed during surveys in 2012 and
2013.

Western bumblebees, which usually have a distinctive white patch on their
tail ends -- hence their other common name, white-bottomed bees -- are key
pollinators of cranberries, blueberries, cherries, greenhouse tomatoes and
other species. Their recent reappearance in Washington and Colorado has
surprised and delighted both amateur and professional entomologists,
particularly because the species is among several North American bumblebees
known to be shrinking in numbers and range. One of them, in fact, Bombus
franklini, a related Oregon species known as Franklin's bumblebee, is feared
extinct.

Like the better-publicized declines of European honeybees, which were
introduced to the United States in the 17th century, researchers suspect
that bumblebee declines are caused by a combination of factors, including
disease and climate and habitat change. And each species decline may have
its own story. The Western bumblebee crash in the 1990s is thought to have
been caused by a fungus, Nosema bombi, which may have been introduced to the
U.S. by commercially bred bumblebee queens from Europe. Another Nosema
species, ceranae, has also been implicated in honeybee declines.

No one is certain why and how the Western bumblebee has reappeared, but it's
possible that the species is now developing resistance to the Nosema fungus.
"We may have hit the mutation jackpot," says Peterman.

Researchers from the University of Washington and the Xerces Society, an
invertebrate conservation group based in Portland, Ore., are now looking for
more Western bumblebee populations, and four additional sightings were
confirmed in and around Seattle this summer. If the species does make a
comeback, says the Xerces Society's Rich Hatfield, it will likely have room
to re-establish: The society is working with farmers to plant
pollinator-friendly flowers and shrubs in field margins and other fallow
lands, an effort that's created about 100,000 acres of pollinator habitat
nationwide. And some species of native bumblebees are still doing well along
the West Coast, suggesting that at least some suitable Western bumblebee
habitat persists.

Farmers value bumblebees because they use their tiny jaws to bite and shake
each flower, a distinctive and efficient pollen-dislodging practice known as
"buzz pollination." Humans can mimic buzz pollination with various gadgets,
including electric toothbrushes, but the process is laborious and
prohibitively expensive on a large scale. Private companies have been trying
to breed Bombus occidentalis in captivity, says Jim Strange of Utah State
University, but have struggled to protect bees from fungal infection. Since
the Western bumblebee population crash, some farmers of bumblebee-reliant
crops have resorted to honeybees, which can manage the job but aren't as
effective, or have purchased bees from a related Eastern species, Bombus
impatiens.

But many conservationists oppose the introduction of non-native bumblebees
into the region, fearing the spread of new diseases. In 2010, the Xerces
Society and other conservation groups petitioned the U.S. Department of
Agriculture to create regulations preventing the movement of bumblebees
outside their native ranges. While the federal government did not act on the
petition, in 2012 the Oregon Department of Agriculture formalized a
longstanding informal ban on the importation of exotic bumblebees into the
state. California allows the use of non-native bumblebees in greenhouses,
but not in open fields.

If the Western bumblebee is in fact developing Nosema resistance, the
species may someday repopulate its former range -- and Western farmers may
once again be able to purchase native bumblebees for their greenhouse
tomatoes and blackberry fields. For now, though, bee enthusiasts like Will
Peterman can only keep an eye on the hedges, looking for another white tail
end.

_______

Scott Hoffman Black

Executive Director

     The Xerces Society for Invertebrate Conservation

Chair

     IUCN Butterfly Specialist Group

The Xerces Society for Invertebrate Conservation

628 NE Broadway, Suite 200, Portland, OR 97232, USA

 <https://webmail.integra.net/src/compose.php?send_to=sblack%40xerces.org>
sblack at xerces.org

Tel: (503) 232-6639 ext. 101

Toll free: 1-855-232-6639 ext. 101

Cell: (503) 449-3792

Connect with Xerces:
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The Xerces Society for Invertebrate Conservation is an international
nonprofit organization that protects wildlife through the conservation of
invertebrates and their habitat.

To join the Society, make a contribution, or read about our work, please
visit  <http://www.xerces.org/> www.xerces.org.

Buy our best-selling book:

<http://www.xerces.org/announcing-the-publication-of-attracting-native-polli
nators/> Attracting Native Pollinators. Protecting North America's Bees and
Butterflies

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