[Pollinator] Steep drop in 4 bumble bee species is a 'wake-up call'

[Scott Black]

cid:image001.png at 01CBB625.E3B49920

WILDLIFE: Steep drop in 4 bumble bee species is a 'wake-up call'
(01/17/2011)

http://www.eenews.net/Greenwire/2011/01/17/12/

Amanda Peterka, E&E reporter

For a handful of scientists in the country, a study published earlier this
month detailing the drastic decline of four North American bumble bee
species was confirmation of a trend they have been observing for years.

The three-year study, published in the Proceedings of the National Academy
of Sciences, found that the populations of four common species of bumble
bees have declined by up to 96 percent in North America. And not only have
the populations gone down in number, but their geographic ranges have also
become smaller.

Bumble bee scientists have observed declines among individual species for
about a decade now, but this is among the first long-term studies on a
national scope and among the first to gain strong media attention.

The study's lead author, Sydney Cameron, said she hopes the results serve as
a "wake-up call to be observant toward our wild bees and to pay attention to
our wild bees."

For the most part, long-term research and funding has focused on
commercially raised honey bees and their decline, termed "colony collapse
disorder" for lack of a clear understanding of its cause. The honey bee
industry has the backing of lobbyists, almond boards and much U.S.
Department of Agriculture funding due to its multibillion-dollar economy,
Cameron said.

Meanwhile, there are perhaps fewer than 20 scientific researchers working
with the approximately 50 North American wild bumble bee species, according
to David Inouye, one of those researchers and a professor of biology at the
University of Maryland.

Interest, however, is growing. Scientists credit Robbin Thorp, a professor
emeritus of entomology at the University of California, Davis.

In 1998, USDA was investigating whether a species known as Franklin's bumble
bee should be listed as endangered, and Thorp began monitoring the species
found only in Northern California and southern Oregon.

"I found it everywhere I looked," Thorp said.

In a couple of years, though, the numbers began to drop off precipitously,
as did the population of the Western bumble bee, one of the study's
declining species. Other species were doing well.

"It began to occur to me that this was a problem that was kind of unique to
those two species, and they happened to be very closely related, and they're
very closely related to the one in Europe that is being used commercially
for greenhouse pollination," Thorp said.

Thorp's hypothesis is that U.S. queen bees caught a bug from European bees
when USDA shipped bees to Europe to rear them there in the early 1990s
because the United States did not have commercial rearing facilities.

Researchers now advocate for bans on overseas and cross-country shipments of
bumble bees and support local commercial bumble bee production. USDA's
Animal and Plant Health Protection Service has already prohibited the
importation of foreign bumble bees, something that Inouye called "shutting
the barn door after the horses are out."

Only one Franklin's bumble bee has been found in the past four years,
according to Scott Hoffman Black, executive director of the Xerces Society,
an invertebrate conservation organization. Xerces is petitioning the U.S
Fish and Wildlife Service to list the species under the Endangered Species
Act.

"Robbin Thorp has potentially watched and studied as Franklin's bumble bee
has gone extinct," Black said. "Although we are hopeful there are some
resilient populations we don't know about out there, at this point, this
bumble bee is on the verge of extinction."

Thorp's work spurred interest in the U.S. bumble bee community, and
researchers began observing declines in other species. But, "for the vast
majority of our bumble bees, we have no knowledge of what their populations
are doing at all because nobody's out there looking at them," Thorp said.

Meanwhile, declines in England have been well-documented, where there is
much more readily available information about the distribution, diversity
and abundance of bumble bees, Inouye said. He attributes that information to
a wealth of historical data.

"I think there's a growing interest here in the United States in terms of
that kind of natural history, but it's a relatively recent change here
whereas in England there's just a long tradition of people being interested
in that kind of thing," Inouye said.

'Potentially catastrophic' losses seen

The report released this month studied eight different species and compared
more than 73,000 museum records to nationwide surveys of living bumble bees.
Some of the species were chosen because researchers had previously observed
declines, and others were chosen because they showed signs of expansion.
Franklin's bumble bee was not included.

Some of the species found to be declining had very broad ranges. The species
known as the American bumble bee is found in the eastern United States all
the way to the Rocky Mountains. The study showed the bee absent from much of
its historical northern and eastern territory.

The four species "were dominant where they were, they have wide ranges, some
of them especially wide ranges," said Cameron, an entomologist at the
University of Illinois, Urbana-Champaign. "And they occurred in high
abundance where they were found."

Seventy percent of wild plants are pollinated by insects, mostly bees, Black
said. He called the declines "potentially catastrophic."

Bumble bees are especially important because they are robust animals and
able to withstand cold temperatures, meaning they are the primary bees in
tundra regions, Cameron said. Bumble bees also have long tongues, allowing
them to pollinate long-tubed flowers.

They also pollinate plants important to humans -- tomatoes, eggplants,
peppers, blueberries and cranberries -- through a behavior called "buzz
pollination." When a bumble bee buzzes at a specific frequency near the
flowers of these plants, the plants' pores open in response.

The study cites the spread of Nosema bombi, the disease bumble bees may have
gotten from Europe, as one possible cause of the decline. Reduced genetic
diversity may be responsible, but the study is clear that the causes for the
decline are still uncertain.

A study published in PLoS ONE in December found that disease from honey bees
can spread to bumble bees through pollen.

Inouye also points to climate change as a possible cause. He found evidence
that bumble bees are moving up in altitude in the Rocky Mountains as
lowlands become warmer. There, they come into contact and possibly into
competition with species already found at those altitudes.

Cameron and Thorp recently received funding from USDA to test the hypothesis
that the European disease pathogen could be causing the decline. They will
study museum specimens to see if they can find Nosema bombi's signature,
Thorp said.

In general, researchers say much more study is needed. The bumble bee
community, while galvanized, lacks the manpower and funding needed to
observe all of North America's species.

"We are heartened that our efforts and the efforts of other conservation
organizations have highlighted the need for more funding for bumble bees and
other native species, and we are seeing a move in that direction," Black
said. "I don't think it's enough yet, I think we can do more, and I think we
do need additional funding. But at least we've started to take a serious
look at these species."

 

 

*************************

Scott Hoffman Black

Executive Director

The Xerces Society for Invertebrate Conservation

Chair

IUCN (International Union for Conservation of Nature) Butterfly 

Specialist Group

4828 SE Hawthorne

Portland, OR 97215

Direct line (503) 449-3792

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

 

The Xerces Society 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/>
http://www.xerces.org/>www.xerces.org.

 

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