[Pollinator] The San Francisco Chronicle: Could genetically modified crops be killing bees?

[Jennifer Tsang]

http://sfgate.com/cgi-bin/article.cgi?f=/c/a/2007/03/10/HOG5FOH9VQ1.DTL


Could genetically modified crops be killing bees?


John McDonald, Special to The Chronicle

Saturday, March 10, 2007

 
<http://sfgate.com/cgi-bin/object/article?f=/c/a/2007/03/10/HOG5FOH9VQ1.DTL&
o=0&type=printable> Bees scurry over a honeycomb frame; beekeepers and
biolog...

With reports coming in about a scourge affecting honeybees, researchers are
launching a drive to find the cause of the destruction. The reasons for
rapid colony collapse are not clear. Old diseases, parasites and new
diseases are being looked at. 

Over the past 100 or so years, beekeepers have experienced colony losses
from bacterial agents (foulbrood), mites (varroa and tracheal) and other
parasites and pathogens. Beekeepers have dealt with these problems by using
antibiotics, miticides or integrated pest management. 

While losses, particularly in overwintering, are a chronic condition, most
beekeepers have learned to limit their losses by staying on top of new
advice from entomologists. Unlike the more common problems, this new die-off
has been virtually instantaneous throughout the country, not spreading at
the slower pace of conventional classical disease. 

As an interested beekeeper with some background in biology, I think it might
be fruitful to investigate the role of genetically modified or transgenic
farm crops. Although we are assured by nearly every bit of research that
these manipulations of the crop genome are safe for both human consumption
and the environment, looking more closely at what is involved here might
raise questions about those assumptions. 

The most commonly transplanted segment of transgenic DNA involves genes from
a well-known bacterium, bacillus thuringiensis (Bt), which has been used for
decades by farmers and gardeners to control butterflies that damage cole
crops such as cabbage and broccoli. Instead of the bacterial solution being
sprayed on the plant, where it is eaten by the target insect, the genes that
contain the insecticidal traits are incorporated into the genome of the farm
crop. As the transformed plant grows, these Bt genes are replicated along
with the plant genes so that each cell contains its own poison pill that
kills the target insect. 

In the case of field corn, these insects are stem- and root-borers,
lepidopterans (butterflies) that, in their larval stage, dine on some region
of the corn plant, ingesting the bacterial gene, which eventually causes a
crystallization effect in the guts of the borer larvae, thus killing them. 

What is not generally known to the public is that Bt variants are available
that also target coleopterans (beetles) and dipterids (flies and
mosquitoes). We are assured that the bee family, hymenopterans, is not
affected. 

That there is Bt in beehives is not a question. Beekeepers spray Bt under
hive lids sometimes to control the wax moth, an insect whose larval forms
produce messy webs on honey. Canadian beekeepers have detected the
disappearance of the wax moth in untreated hives, apparently a result of
worker bees foraging in fields of transgenic canola plants. 

Bees forage heavily on corn flowers to obtain pollen for the rearing of
young broods, and these pollen grains also contain the Bt gene of the parent
plant, because they are present in the cells from which pollen forms. 

Is it not possible that while there is no lethal effect directly to the new
bees, there might be some sublethal effect, such as immune suppression,
acting as a slow killer? 

The planting of transgenic corn and soybean has increased exponentially,
according to statistics from farm states. Tens of millions of acres of
transgenic crops are allowing Bt genes to move off crop fields. 

A quick and easy way to get an approximate answer would be to make a
comparison of colony losses of bees from regions where no genetically
modified crops are grown, and to put test hives in areas where modern
farming practices are so distant from the hives that the foraging worker
bees would have no exposure to them. 

Given that nearly every bite of food that we eat has a pollinator, the
seriousness of this emerging problem could dwarf all previous food
disruptions. 

John McDonald is a beekeeper in Pennsylvania. He welcomes comments or
questions about the bee problem at mcbee_77 at yahoo.com. General comments to
home at sfchronicle.com. 

http://sfgate.com/cgi-bin/article.cgi?f=/c/a/2007/03/10/HOG5FOH9VQ1.DTL

This article appeared on page F - 4 of the San Francisco Chronicle

 

Jennifer Tsang
 <http://coevolution.org> Coevolution Institute
423 Washington St. 5th Fl.
San Francisco, CA 94111-2339
T: 415.362.1137

F: 415.362.3070

 <http://www.nappc.org> www.nappc.org

 <http://www.pollinator.org> www.pollinator.org

 

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