[Pollinator] Stinging descent: Researchers trying to figure out why bumblebees are disappearing

[Scott Black]

knoxnews.com

Science


Stinging descent

Researchers trying to figure out why bumblebees are disappearing
[]

By Morgan Simmons
Thursday, April 10, 2008

The collapse of honeybee colonies across the U.S. 
appears to have a parallel among bumblebees.

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).

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.

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.

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.

Scott Black, executive director of the Xerces 
Society, said it's going to take time to unravel the mystery.

"Most people aren't even aware," Black said. 
"That's why we started this campaign."

One of the disappearing bumblebees, the 
rusty-patched bumblebee, once was abundant 
throughout the Eastern United States, said Black.

"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."

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.

Other factors may include habitat destruction, 
pesticides, invasive species, natural pest or 
predator population cycles and even climate change.

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.

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.

"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."

The Smokies are home to 13 species of bumblebees.

Mayor said one of the park's more common 
bumblebee species, Bombus bimaculatus, does not appear to be in trouble.

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.

Tomatoes, peppers and blueberries are some of the 
plants that require buzz pollination.

Janet Rock, a botanist with the Smokies, said the 
park contains several rare plants that include 
bumblebees among their pollinators.

According to the Xerces Society, the economic 
value of insect-pollinated crops in the U.S. in 
2000 was estimated at $20 billion.

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.

Honeybees are not considered a native species 
since they did not exist in North America until 
European settlers brought them over.

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.

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.

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.

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.

"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.

"With other native bees, there's a paucity of knowledge."

© 2008 Knoxville News Sentinel



*************************
Scott Hoffman Black
Ecologist/Entomologist
Executive Director
The Xerces Society for Invertebrate Conservation
4828 SE Hawthorne
Portland, OR 97215
Direct line (503) 449-3792
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/>www.xerces.org.


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