Published on Thursday, October 19, 2006 by the San Francisco Chronicle
<http://www.sfgate.com/cgi-bin/article.cgi?file=/c/a/2006/10/19/MNGA0LRRK31.DTL&type=printable>
Loss of Species that Pollinate is Cause for Global Alarm, Researchers say
by Juliet Eilperin
Birds, bees, bats and other species that pollinate North American plant
life are losing population, according to a study released Wednesday by
the National Research Council. This "demonstrably downward" trend could
damage dozens of commercially important crops, scientists warned,
because three-fourths of all flowering plants depend on pollinators for
fertilization.
'CAUSE FOR GLOBAL ALARM'
Bees feed on pollen from a wild flower in Amman, May 31, 2005. Bees and
other important pollinators such as birds and bats may be on the decline
in the U.S., putting crops and other plants at risk, experts reported on
Wednesday. (Ali Jarekji/Reuters)
American honeybees, which pollinate more than 90 domestic commercial
crops, have declined by 30 percent in the past 20 years. This poses a
challenge to agricultural interests such as California almond farmers,
who need about 1.4 million colonies of honeybees to pollinate 550,000
acres of their trees. By 2012, the state's almond farmers are expected
to need bees to pollinate 800,000 acres.
Gene Robinson, an entomologist at University of Illinois,
Urbana-Champaign and one of the 15 researchers who produced the report,
said U.S. farmers had to import honeybees last year for the first time
since 1922, underscoring the extent of the problem.
"The honeybee industry is at a critical juncture," Robinson said. "The
time for action is now."
A number of factors have cut pollinators' numbers in recent decades, the
researchers said. Pesticides and introduced parasites such as the varroa
mite have hurt the honeybee population. Bats, which carry pollen to a
variety of crops, have declined as vandalism and development destroyed
some of their key cave roosts.
John Karges, a Nature Conservancy conservation biologist who works with
the federally endangered Mexican long-nosed bat in west Texas, said the
bat's U.S. population fell from 10,000 in 1967 to 1,000 in 1983. The
species feeds on nectar from the agave plant, which can be used to
produce a sweetener as well as tequila.
"This bat is rare and suspected of declining rangewide," said Karges,
noting that it can now be spotted only at one protected cave site in Big
Bend National Park. "I don't think anyone's looking at it annually or
closely."
The declines have been gradual and in some instances are hard to
quantify, the committee concluded. But the panel's chairwoman,
entomologist May Berenbaum of the University of Illinois,
Urbana-Champaign, said in a statement that there is already cause for
alarm.
"Despite its apparent lack of marquee appeal, a decline in pollinator
populations is one form of global change that actually has credible
potential to alter the shape and structure of terrestrial ecosystems,"
Berenbaum said.
Animals carry pollen, which they pick up inadvertently while feeding on
a plant's nectar, and transfer it from one flowering plant to another,
sometimes over significant distances. The process not only boosts plant
production but increases species' genetic diversity.
Animal pollinators fertilize more than 187,500 flowering plants
worldwide. Scientists believe these plants, called angiosperms, gained
ecological dominance more than 70 million years ago in part because
animals help them disperse their pollen so broadly. Other pollinators
include hummingbirds and butterflies, as well as wild bees.
In many ways pollination works as a chain, said committee member Peter
Kevan, a professor at the University of Guelph in Ontario, in which even
the largest animals depend on small insects.
"Canadian black bears need blueberries, and the blueberries need bees"
for pollination, Kevan said. "Without the bees you don't have
blueberries, and without the blueberries you don't have black bears."
Despite this crucial link, Robinson said, many ordinary citizens fail to
grasp how important pollinators are to food production.
European researchers also have documented serious declines: The
diversity of bee species has declined by 40 percent in the United
Kingdom and 60 percent in Holland since 1980. Europeans have more
detailed records of pollinators than Americans, said University of
Arizona entomologist Stephen Buchmann, partly because they have more
amateur taxonomists keeping track of them.
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