In a message dated 1/5/2012 12:08:05 A.M. Central Standard Time,
[log in to unmask] writes:
To readers,
Sierra Club's Genetic Engineering Action Team has been following the
connection between the honeybee demise and exposure to corn seeds coated with
neonicotinoids.
Included here is info about the latest research.
Laurel Hopwood, Chair, Sierra Club Genetic Engineering Action Team
CATCH THE BUZZ - Corn Seed Pesticide Kills Bees
Corn Seed Treatment As Lethal As It Gets For Honey Bees All Season Long,
And Long After The Season Is Gone. It Just Keeps On Killing.
by Alan Harman
(EDITED)
Frightening new research shows honey bees are being exposed to deadly
neonicotinoid insecticides and several other agricultural pesticides throughout
their foraging period. The research, published in the scientific journal
PLoS One says extremely high levels of clothianidin and thiamethoxam were
found in planter exhaust material produced during the planting of treated
maize seed. The work, which could raise new questions about the long-term
survival of the honey bee, was conducted by Christian H. Krupke of the
Department of Entomology at Purdue University, Brian D. Eitzer of the Department of
Analytical Chemistry at the Connecticut Agricultural Experiment Station
and Krispn Given of Purdue.
"Neonicotinoids were found in the soil of each field we sampled, including
unplanted fields," they report. Dandelions visited by foraging bees
growing near these fields were found to contain neonicotinoids as well. "This
indicates deposition of neonicotinoids on the flowers, uptake by the root
system, or both. Dead bees collected near hive entrances during the spring
sampling period were found to contain clothianidin as well."
"These results have implications for a wide range of large-scale annual
cropping systems that utilize neonicotinoid seed treatments," the report
says. The research was funded by grants from the North American Pollinator
Protection Campaign and the Managed Pollinator Coordinated Agricultural
Project.
Neonicotinoids are persistent. The new report says the half-lives of these
compounds in aerobic soil conditions can vary widely, but are best
measured in months - 148 - 1,155 days for clothianidin.
Among the largest single uses of these compounds is application to maize
seed. Production of maize for food, feed and ethanol production represents
the largest single use of arable land in North America, reaching a record
88,216,620 acres in 2010 and is expected to increase. All of the maize
seed planted in North America except for 0.2% used in organic production is
coated with neonicotinoid insecticides.
Two major compounds are used - clothianidin and thiamethoxam, with the
latter metabolized to clothianidin in the insect. The application rates for
these compounds range from 0.25 to 1.25 mg/kernel. These compounds are highly
toxic to honey bees - a single kernel contains several orders of magnitude
of active ingredient more than the published LD50 values for honey bees -
defined as the amount of material that will kill 50% of exposed individuals.
In fact, the amount of clothianidin on a single maize seed at the rate of
0.5 mg/kernel contains enough active ingredient to kill more than 80,000
honey bees.
The results prompted researchers to carry out more experiments to
determine how honey bees may be gaining exposure to clothianidin and other
pesticides commonly applied to either maize seed or to plants later in the season.
They collected samples from a variety of potential exposure routes near
agricultural fields and analyzed them to determine whether pesticides were
present. They sampled soils, pollen both collected by honey bees and directly
from plants, dandelion flowers, and dead and healthy bees. They even
checked waste products produced during the planting of treated seed. Maize seed
is sewn with tractor-drawn planters that use a forced air/vacuum system and
a perforated disc to pick up individual seeds and drop them into the
planting furrow at the selected spacing. Maize kernels treated with
neonicotinoids and other compounds such as fungicides do not flow readily and may stick
to one another, causing uneven plant spacing. To overcome this, talc (a
mineral composed of hydrated magnesium silicate) is added to seed boxes to
reduce friction and stickiness and ensure the smooth flow of seed. Much of the
talc is exhausted during planting, either down with the seed or behind the
planter and into the air using an exhaust fan. Researchers sampled the
waste talc after planting to determine whether this material was contaminated
with pesticides abraded from treated seeds. The waste is a mixture of the
talc that has been in contact with treated maize kernels and minute pieces of
the seeds.
"Soil collected from areas near our test site revealed that neonicotinoid
insecticide residues were present in all samples tested, with clothianidin
occurring in each field sampled ... These results demonstrate that honey
bees living and foraging near agricultural fields are exposed to
neonicotinoids and other pesticides through multiple mechanisms throughout the spring
and summer ... We show that bees living in these environments will forage
for maize pollen and transport pollen containing neonicotinoids to the hive."
The results also showed clothianidin present in the surface soil of fields
long after treated seed has been planted. "All soil samples we collected
contained clothianidin, even in cases where no treated seed had been planted
for two growing seasons," the report says.
During the spring planting period, dust that arises from this soil may
land on flowers frequented by bees, or possibly on the insects themselves. Of
potentially greater concern are the very high levels of neonicotinoids and
fungicides found in the talc that has been exposed to treated seed. "The
large areas being planted with neonicotinoid treated seeds, combined with the
high persistence of these materials and the mobility of disturbed soil and
talc dust, carry potential for effects over an area that may exceed the
boundaries of the production fields themselves."
Later in the season, when planting is largely complete, the researchers
found bees collect maize pollen that contains translocated neonicotinoids and
other pesticides from seed. Translocation of neonicotinoids into pollen
has previously been reported for maize grown from imidacloprid-treated seed,
but the researchers say the degree to which honey bees in their study
gathered maize pollen was surprising. "The finding that bee-collected pollen
contained neonicotinoids is of particular concern because of the risks to
newly-emerged nurse bees, which must feed upon pollen reserves in the hive
immediately following emergence," they say.
"Lethal levels of insecticides in pollen are an obvious concern, but
sub-lethal levels are also worthy of study as even slight behavioral effects may
impact how affected bees carry out important tasks such as brood rearing,
orientation and communication." Also potentially important are the three
fungicides found in bee-collected pollen samples - trifloxystrobin and
azoxystrobin and propiconazole. Azoxystrobin and trifloxystrobin are frequently
used in maize seed treatments as protectants and all three are widely
applied to maize in North America, even in the absence of disease symptoms. These
findings have implications both for honey bees located near these crops
year-round, but also for migratory colonies which pollinate crops such as a
lmonds and other fruit and nut crops, the report says.
To read the study, click here:
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0029268
To read our actions on the honeybee demise, click these five sites:
http://www.sierraclub.org/biotech/whatsnew/whatsnew_2009-11-10.asp
Want to eat? Save the honeybee!
http://www.sierraclub.org/biotech/whatsnew/whatsnew_2009-11-09a.asp
Sierra Club comments on a "neonic" insecticide
http://www.sierraclub.org/biotech/whatsnew/whatsnew_2008-07-30.asp
Sierra Club urges EPA to suspend nicotinyl insecticides
http://www.sierraclub.org/biotech/whatsnew/whatsnew_2007-04-07.asp
USDA, Lobbyists and Bees
http://www.sierraclub.org/biotech/whatsnew/whatsnew_2007-03-21.asp
GE and bee Colony Collapse Disorder -- science needed!
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