Air Pollution Impedes Bees' Ability to Find Flowers|
By Juliet Eilperin
Washington Post Staff Writer
Monday, May 5, 2008
Air pollution interferes with the ability of bees and other insects to follow
the scent of flowers to their source, undermining the essential process of
pollination, a study by three University of Virginia researchers suggests.
Their findings may help unlock part of the mystery surrounding the current
pollination crisis that is affecting a wide variety of crops. Scientists are
seeking to determine why honeybees and bumblebees are dying off in the United
States and in other countries, and the new study indicates that emissions from
power plants and automobiles may play a part in the insects' demise.
Scientists already knew that scent-bearing hydrocarbon molecules released by
flowers can be destroyed when they come into contact with ozone and other
pollutants. Environmental sciences professor Jose D. Fuentes at the University
of Virginia -- working with graduate students Quinn S. McFrederick and James C.
Kathilankal -- used a mathematical model to determine how flowers' scents travel
with the wind and how quickly they come into contact with pollutants that can
destroy them. They described their results in the March issue of the journal
In the prevailing conditions before the 1800s, the researchers calculated
that a flower's scent could travel between 3,280 feet and 4,000 feet, Fuentes
said in an interview, but today, that scent might travel 650 feet to 1,000 feet
in highly polluted areas such as the District of Columbia, Los Angeles or
"That's where we basically have all the problems," Fuentes said, adding that
ozone levels are particularly high during summer. "The impacts of pollution on
pollinator activity are pronounced during the summer months."
This phenomenon triggers a cycle, the authors noted, in which the pollinators
have trouble finding sufficient food, and as a result their populations decline.
That, in turn, translates into decreased pollination and keeps flowering plants,
including many fruits and vegetables, from proliferating.
Fuentes said scientists now have a more sophisticated understanding of the
signals for which insects are searching, and that air pollution rapidly
eliminates as much as 90 percent of flowers' aroma.
"We now know what the pollinators are looking for when they're actually
looking for the flowers," he said.
Most bees have poor eyesight, which makes scent particularly important, the
Since 2006, honeybee colonies in the United States have been suffering from a
widespread phenomenon known as colony collapse disorder (CCD), in which adult
worker bees abandon an otherwise-healthy hive.
John P. Burand, an associate professor at the University of Massachusetts at Amherst who is studying bee colony
collapses, said the effects of air pollution described in the new study are
probably not directly related to that phenomenon. But, he added in an e-mail:
"There is no doubt that air pollution and air quality is having an effect on
bees and other pollinators. It appears there is more than one factor that is
contributing to the CCD phenomenon we are seeing with bees, and certainly air
pollution in some fashion may be playing a role."
Burand, working with two other University of Massachusetts researchers and an
insect ecologist at the University of Maine at Orono, just received a $150,000, three-year
grant from the Agriculture Department to analyze microbes carried by bees that
pollinate apples, squash and pumpkins. They are working with colleagues to
compare the bacteria, viruses and fungi in healthy bee colonies with those in
Richard Poirot, an air-quality planner at Vermont's Department of
Environmental Conservation who helps advise the federal government on its
national ozone standards, said it makes sense that the chemical reaction of
floral hydrocarbons and pollutants such as ozone would reduce the power of a
flower's scent and affect the insects that depend on those aromas.
"It does make sense that it certainly would be another stress factor" on
pollinators, Poirot said, though he added that pollinators are declining for an
array of reasons not related to pollution. "The question is, how significant is
Timothy H. Tear, a senior scientist at the advocacy group the Nature Conservancy who studies the impact of air pollution on
ecosystems, said the recent study confirms the extent of ozone's effects on
habitats up and down the East Coast.
"We know that ozone levels continue to be high and go well beyond EPA standards for public health," Tear said. "What's been pretty
consistent is the more we look at air pollution's impacts on natural resources,
the more we find those impacts to be."
Tear and his colleagues have recently completed a survey of how atmospheric
pollution is affecting biodiversity in the Eastern United States and concluded
that high levels of ozone can decrease forest growth by as much as 30
Original article: Washington Post
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