Pollinators Help One-Third Of World Crop Production
Honey bees (pictured), particularly ones in the wild versus those in
managed hives, are negatively impacted by habitat loss and a variety of
non-sustainable farming practices.
by Sarah Yang
Berkeley CA (SPX) Oct 27, 2006
Pollinators such as bees, birds
<http://www.terradaily.com/reports/Pollinators_Help_One_Third_Of_World_Crop_Production_999.html#>
and bats affect 35 percent of the world's crop production
<http://www.terradaily.com/reports/Pollinators_Help_One_Third_Of_World_Crop_Production_999.html#>,
increasing the output of 87 of the leading food crops worldwide, finds a
new study published in the Proceedings of the Royal Society B:
Biological Sciences and co-authored by a conservation biologist at the
University of California, Berkeley.
The study is the first global estimate of crop production that is
reliant upon animal pollination. It comes one week after a National
Research Council (NRC) report detailed the troubling decline in
populations of key North American pollinators, which help spread the
pollen needed for fertilization of such crops as fruits, vegetables,
nuts, spices and oilseed. Of particular concern in the NRC report was
the decline of the honey bee, a species
<http://www.terradaily.com/reports/Pollinators_Help_One_Third_Of_World_Crop_Production_999.html#>
introduced from Europe and a critical pollinator for California's almond
industry.
The report pointed out that it takes about 1.4 million colonies of honey
bees to pollinate 550,000 acres of this state's almond trees.
In an effort to better understand how dependent crop production is upon
pollinators worldwide, an international research team led by
Alexandra-Maria Klein, an agroecologist from the University of
Goettingen in Germany, conducted an extensive review of scientific
<http://www.terradaily.com/reports/Pollinators_Help_One_Third_Of_World_Crop_Production_999.html#>
studies from 200 countries and for 115 of the leading global crops.
Claire Kremen, an assistant professor at UC Berkeley's Department of
Environmental Science
<http://www.terradaily.com/reports/Pollinators_Help_One_Third_Of_World_Crop_Production_999.html#>,
Policy, and Management, is co-author of this new study.
"There's a widely stated phrase in agriculture
<http://www.terradaily.com/reports/Pollinators_Help_One_Third_Of_World_Crop_Production_999.html#>
that you can thank a pollinator for one out of three bites of food you
eat," said Kremen, who is also a member of the Committee on Status of
Pollinators that produced the NRC report and leader of a group at the
National Center for Ecological and Analysis and Synthesis that
co-sponsored the work. "However, it wasn't clear where that calculation
came from, so we set out to do a more thorough and reproducible
estimate, and we wanted to look at the impact on a global scale."
What the researchers found fell in line with the dictum to which Kremen
referred. Out of the 115 crops studied, 87 depend to some degree upon
animal pollination, accounting for one-third of crop production
globally. Of those crops, 13 are entirely reliant upon animal
pollinators, 30 are greatly dependent and 27 are moderately dependent.
The crops that did not rely upon animal pollination were mainly staple
crops such as wheat, corn and rice.
The NRC report notes that honey bees in North America have been
decimated by infestations of parasitic mites that were inadvertently
introduced to the United States. In addition, honey bees are battling
antibiotic-resistant pathogens and competition from Africanized honey bees.
Kremen added that honey bees, particularly ones in the wild versus those
in managed hives, are negatively impacted by habitat loss and a variety
of non-sustainable farming practices. These impacts also affect native
species of wild bees. There are 4,000 species of native bees in North
America alone.
"We've replaced pollination services formerly provided by diverse groups
of wild bees with domesticated honey bees," said Kremen, who recently
co-authored another study showing that wild bees interacting with honey
bees can lead to a five-fold increase in pollination efficiency. "The
problem is, if we don't protect the wild pollinators, we don't have a
backup plan."
Kremen suggested an approach to a more sustainable form of agriculture,
one that de-emphasizes the use of synthetic fertilizers and builds in
more of a reliance on natural ecosystems.
Some changes may involve mere tweaks to current practices, such as
allowing weeds and native plants to grow and prosper along the border of
the primary crop, she said. Such non-crop plants, which are currently
killed off by herbicides, can sustain a variety of wild bee species when
the primary crops are not in bloom.
Another change could be to switch from flood irrigation, which drowns
bee species that nest in the ground, to spray irrigation when feasible,
said Kremen.
The study in the Proceedings of the Royal Society B highlights what is
at stake if steps to improve pollinator biodiversity are not taken.
"Passion fruits in Brazil are hand-pollinated through expensive
day-laborers as the natural pollinators, carpenter bees, are hardly
available because of high insecticide use in the agricultural fields and
the destruction of the natural habitats," said lead author Klein.
Klein said that in the cities of Brazil, the high prices for fruits and
vegetables are pushing people to turn to less healthy alternatives,
including fatty meats and sugar products. As a result, she said, obesity
rates seem to be rising.
"The stability of crop yields not only depends on pollination, but also
on further ecosystem services," Klein added. "Therefore, we need
landscapes carefully managed for a diversity of functionally important
groups of organisms that sustain many important ecosystem services such
as pollination, pest, pathogen and weed control, and decomposition."
This study was also supported by the Sixth European Union Framework program.
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