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Science<br><br>
<h3><b>Stinging descent</b></h3>Researchers trying to figure out why
bumblebees are disappearing <br>
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By Morgan Simmons <br>
Thursday, April 10, 2008 <br>
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The collapse of honeybee colonies across the U.S. appears to have a
parallel among bumblebees.<br>
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In the late 1990s, researchers began noticing a dramatic decline in three
of North America's most common bumblebee species - the western bumblebee
(Bombus occidentalis), yellow-banded bumblebee (Bombus terricola) and the
rusty-patched bumblebee (Bombus affinis).<br>
<br>
Of these species, the yellow-banded and rusty-patched bumblebees are
found in the Eastern U.S., where they play an important role in crop and
wildflower pollination.<br>
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The Xerces Society, a nonprofit organization dedicated to the
conservation of invertebrates, has launched a nationwide effort to piece
together the current and former distribution of these species.<br>
<br>
In addition to working with scientists, the organization also is reaching
out to beekeepers, gardeners and state agencies to determine the current
status of these bumblebees.<br>
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Scott Black, executive director of the Xerces Society, said it's going to
take time to unravel the mystery.<br>
<br>
"Most people aren't even aware," Black said. "That's why
we started this campaign."<br>
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One of the disappearing bumblebees, the rusty-patched bumblebee, once was
abundant throughout the Eastern United States, said Black.<br>
<br>
"If you grew up in Maine down to Tennessee and across to Minnesota,
you would have seen this bumblebee," he said. "We surveyed
dozens of scientists, and they're not finding it anymore."<br>
<br>
Researchers aren't sure what's causing the decline. One theory is that
wild bumblebees have been infected with a pathogen brought back by bees
reared commercially in Europe for the purpose of pollinating greenhouse
tomatoes and other crops.<br>
<br>
Other factors may include habitat destruction, pesticides, invasive
species, natural pest or predator population cycles and even climate
change.<br>
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Researchers at the Great Smoky Mountains National Park have strong
evidence of the bumblebee decline, thanks to the All Taxa Biodiversity
Inventory, a research initiative aimed at collecting, identifying and
cataloguing all the life forms in the park.<br>
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Adriean Mayor, curator for the museum for the park's Twin Creeks Science
and Education Center, said neither the yellow-banded bumblebee nor the
rusty-patched bumblebee have been observed in the Smokies since
2002.<br>
<br>
"When we surveyed them in the 1990s, we got a few specimens,"
Mayor said. "By 2002, people who were collecting in the field told
me these species had essentially disappeared from sites they had been
surveying for years."<br>
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The Smokies are home to 13 species of bumblebees.<br>
<br>
Mayor said one of the park's more common bumblebee species, Bombus
bimaculatus, does not appear to be in trouble.<br>
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Bumblebees are active in cooler weather and lower light levels than
honeybees. They're also "buzz" pollinators, which enables them
to dislodge pollen that otherwise would remain lodged in the flower's
anthers.<br>
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Tomatoes, peppers and blueberries are some of the plants that require
buzz pollination.<br>
<br>
Janet Rock, a botanist with the Smokies, said the park contains several
rare plants that include bumblebees among their pollinators.<br>
<br>
According to the Xerces Society, the economic value of insect-pollinated
crops in the U.S. in 2000 was estimated at $20 billion.<br>
<br>
Scientists say the decline in managed hives of European honeybees because
of disease, pests and Colony Collapse Disorder makes the role of wild
native bees as pollinators even more important.<br>
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Honeybees are not considered a native species since they did not exist in
North America until European settlers brought them over.<br>
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The Smokies have 212 species of native bees. In addition to bumblebees,
they include plasterer bees, cuckoo bees, leafcutter bees, yellow-faced
bees, sweat bees and various species of solitary bees.<br>
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The park's ATBI study has documented 121 species of native bees that were
previously unknown to exist in the Smokies, as well as four species that
are new to science - that is, previously unknown to have existed anywhere
on the planet.<br>
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According to the Xerces Society, the U.S. has 4,000 species of native
bees that pollinate about $3 billion worth of agriculture each year.<br>
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Scott Black of the Xerces Society said he is concerned that native
pollinators in general may be declining because of a range of factors,
including habitat loss from modern farming practices, as well as
pesticides.<br>
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"Most native bees are small and hard for the layperson to
identify," Black said. "The reason we have a sense that
bumblebees are declining is not because they're disappearing at a faster
rate than other native bees, but because they're bigger and easier to
see.<br>
<br>
"With other native bees, there's a paucity of knowledge."<br>
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© 2008 Knoxville News Sentinel<br><br>
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<x-sigsep><p></x-sigsep>
*************************<br>
Scott Hoffman Black<br>
Ecologist/Entomologist<br>
Executive Director<br>
The Xerces Society for Invertebrate Conservation<br>
4828 SE Hawthorne <br>
Portland, OR 97215 <br>
Direct line (503) 449-3792<br>
sblack@xerces.org<br><br>
<i>The Xerces Society is an international, nonprofit organization that
protects wildlife through the conservation of invertebrates and their
habitat. <br>
</i> <br>
To join the Society, make a contribution, or read about our work, <br>
please visit
<a href="http://www.xerces.org/">www.xerces.org</a>.<br><br>
<br>
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