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August 4, 2008
Most of the world's plant species
rely on animals to transfer their pollen to other plants. The
undisputed queen of these animal pollinators is the bee, made up
of about 30,000 species worldwide, whose daily flights aid in
the reproduction of more than half of the world's flowering
plants. In recent years, however, an unprecedented and
unexplained decline in bee populations across the U.S. and
Europe has placed the health of ecosystems and the
sustainability of crops in peril.
In an oral session at the Annual Meeting of the
Ecological Society of America,
an interdisciplinary group of scientists will explore the
problem of bee habitat loss at a broad scale to determine what
can be done to preserve bees in their native habitats. The
session, titled "The Landscape-Scale Ecology of Pollinators and
Pollination," will include scientists in the fields of computer
science, mathematics and ecology from institutions in the U.S.,
Europe and Asia.
The most recent and headline-capturing phenomenon, known as
colony collapse disorder, is characterized by the disappearance
of adult honeybees from beekeeper hives, leaving behind bee
larvae with no caretakers. The bee decline is particularly
unnerving for farmers because an estimated 80 percent of all
food crops are pollinated by honeybees and their wild cousins.
Stymied scientists have proposed a host of reasons for managed
honeybee declines, including climate change, parasites,
diseases, overexposure to pesticides and loss of suitable
habitat; most researchers believe that a combination of these
factors is responsible. In this oral session, scientists turn
their attention to native, wild bees to determine whether they
are undergoing – or might undergo – the same decline.
One of the session's organizers, Neal Williams of Bryn Mawr
College, hopes that the session will result in the synthesis of
ideas from many disciplines. "We want to know: Can we look at
landscape models in a predictive way and use those to inform us
about natural populations and how they deliver pollinator
services to crops?" he asks.
Rachael Winfree of Rutgers University is particularly interested
in the health of native bees as "biological insurance" against
the decline of honeybees. "Over half of the world's native
plants require animal pollinators, and most of those are bees,"
she says. "Native pollinators are serving as a backup plan for
the honeybee."
Winfree will present a study that combines data from over 50
published studies of bee population sizes and diversity. She
found that in areas of extreme fragmentation due to human
development, animal grazing, logging and crop fields, bee
populations were smaller and the number of bee species was lower
than in natural or minimally disturbed areas.
Scientists are also using technological methods to further
understand bee communities. Daniel Chalk, a graduate student at
the University of Exeter in the United Kingdom, used an
artificial intelligence computer model to predict flight
patterns of wild bumblebees. His model is useful because it can
predict how bees would forage, or look for food resources, in
different landscapes.
"Crucially, our model is able to predict the behavior of bees in
larger-scale foraging environments, where the foraging patches
can be thought of as large fields of crops," says Chalk. His
model, he says, could help scientists understand how land
disturbance caused by humans affects bee species richness and
density.
Williams used an experimental approach to understand the
landscape-scale ecology of native bumblebees. He and his
colleagues established 38 bee colonies across central
California, ranging from undisturbed chaparral to organic and
conventional farms. During the course of the summer months, they
found that the further a colony was from natural areas, the
fewer worker bees it sustained. Williams' team also found that
bees always collected pollen from both crops and native plants.
Since crop fields aren't in bloom for the entire bee active
season, Williams says, the bees need an adequate alternative
source of nectar and pollen, and may travel several kilometers
to find it. Therefore, a mosaic landscape that has natural areas
mixed in with agriculture is important to keep bee colonies
healthy.
"Today's landscape is both natural and managed," says Williams.
"It's not just matrix of natural areas with agriculture mixed
in, but a patchwork quilt with animals using all of the areas in
the landscape."
Other presenters in this session include Juliet Osborne of the
Centre for Soils and Ecosystem Function, United Kingdom, who
will speak about bee movement patterns and pollen flow; Yukari
Suzuki-Ohno of Tokohu University, Japan, who will discuss bee
nest site choice; Margarita Lopez-Uribe of Cornell University,
who will talk about the ecology of gene flow among bee
populations; Marcos G.E. Da Luz of Universidade Federal do
Paraná, Brazil, who will discuss how bees search for food
sources; Helen J. Young of Middlebury College, who will discuss
human land use and its relationship to bee flower visitation;
Ralph Grundel of the U.S. Geological Survey, who will speak
about the landscape ecology of bee community composition; and
Berry Brosi of Stanford University, who will talk about bee
floral fidelity.
For more information about this session and other ESA Annual
Meeting activities, visit
http://www.esa.org/milwaukee. The theme of the meeting is
"Enhancing Ecological Thought by Linking Research and
Education." More than 3,500 scientists are expected to attend.
The Ecological Society of America is the world's largest
professional organization of ecologists, representing 10,000
scientists in the United States and around the globe. Since its
founding in 1915, ESA has promoted the responsible application
of ecological principles to the solution of environmental
problems through ESA reports, journals, research, and expert
testimony to Congress. ESA publishes four journals and convenes
an annual scientific conference. Visit the ESA website at
http://www.esa.org. |
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