Sunday, September 20, 2009

Genetically Engineered Corn Killing Stream-Dwelling Insects

"... and consequently the prey biomass available to predators such as fishes, amphibians, and birds."

Remember these two studies from November of last year that found detrimental effects of genetically engineered corn in mice?Here's another study in the same vein:
Toxins In Transgenic Crop Byproducts May Affect Headwater Stream Ecosystems, PNAS, 2007

It's not about mice, but insects that inhabit streams near fields where genetically engineered (GE) corn is planted.

When these insects were fed the byproducts of a corn plant engineered to produce a toxic pesticide in every cell (Bt corn), they experienced reduced growth and increased mortality. Caddisflies (Lepidostoma liba), which are not considered a "target" for the pesticide:
"... had >50% lower growth rates when they were fed Bt corn litter compared with non-Bt corn litter (P=0.008)." (Lower growth rates reduce this species' ability to reproduce.)
Caddisflies (Helicopsyche borealis) that ate Bt corn pollen had a significantly higher mortality (43%) than flies that didn't (18%).

This next part was incredible. The authors state:
"Previous research assumed that transgenic crop byproducts would remain on fields."
And took these photos:

Click to enlarge.

(B) Illustrates a typical headwater agricultural stream during pollen shed with a buffer strip of grass and adjacent corn fields.
(C) Illustrates accumulations of corn byproducts after harvest.

They showed:
"... that corn byproducts, such as pollen and detritus, enter headwater streams and are subject to storage, consumption, and transport to downstream water bodies.

"toxin-containing crop byproducts are dispersed through the landscape by streams."
They warned that:
"Stream insects are important prey for aquatic and riparian predators, and widespread planting of Bt crops has unexpected ecosystem-scale consequences."
I wouldn't want my dog or child playing near those streams. Then I realize we all eat the toxin-containing corn from those genetically engineered plants every day.
Photo at top is of "just hatched caddis fly larvae in a blob of jelly on a leaf." Credit for the photo goes to Sandrine Angelibert. From The Garden Pond Blog. Beautiful. Unfortunate that they are needlessly dying.


Anonymous said...

Don't buy GMOs!

Bix said...

Well, I'll go along with that.

Eric said...

No researcher would assume that crop debris remains on fields. It's part of an interwoven ecosystem. There had to be another reason for them saying that. Besides, if transgenic crops are as benign as the biotech industry says, why even make a statement like that? It wouldn't matter.

Dr. Mel said...

Agree with Eric. Great post, Bix--most illuminating. And these GE crops are being used worldwide--aargh.

Family Nutritionist said...

Your dog and child (congratulations!) are safe. The Bt protein is not toxic to them.

Is Bt corn worse than Bt spary? "The goal of our feeding experiments was to determine whether trichopterans were at all susceptible to the effects of Cry1Ab protein". It is preliminary, and must be followed up with good laboratory dose-response and concentration-response studies, measurements of levels of pollen and crop residue in headwater streams, and studies on Caddisfly dining habits in the wild.

Bix said...

I disagree with you, Family. Bt toxin is not the same as Bt corn. Bt corn is a genetically engineered plant which, by nature of its manufacture, contains possibly thousands of unexpected mutations - mutations that may transcribe proteins that may well be toxic to living organisms, beyond those organisms considered a target, such as dogs and people.

This study tested Bt corn byproducts (e.g. leaves) and Bt pollen. It did not isolate known toxin(s).

According to Jeffrey Smith:

"Genome-wide mutations are found in every GM plant analyzed."

"A single mutation can influence many genes simultaneously. Thus, the insertion process might cause the over production of toxins, allergens, carcinogens, or anti-nutrients, reduce the nutritional quality of the crop, or change the way that the plant interacts with its environment."

I agree with you however that this study should be followed up. It raises a red flag. I'll consider dogs and people safe after I read the results of studies that test these GE plants on them.

Unfortunately, this study's lead author, Emma Rosi-Marshall, was ruthlessly criticized, both personally and professionally, by biotech and agricultural interests after the study's publication. It put the brakes on further research.

This post has also received odd, antagonistic comments from people I don't know.

Family Nutritionist said...

I agree that Bt corn IS different from straight Bt protein (Cry 1Ab?), and both are different from Bt spores. All are toxic to many targetted and non-targetted insect larvae which ingest them. And Bt spores can cause infections in humans and rats (didn't see any dog experiments or case studies listed). Other insecticides are even more dangerous than Bt spores.

GM crops might make food cheaper, as did the introduction of insecticides (including Bt sprays) and synthetic fertilizers. Suddenly turning back the clock is scary because it means famine and economic depression.

What to do?

Bix said...

There is already famine and economic depression.

What can we do?

Well, for one, genetically engineered plants have not solved the hunger crisis. The food crisis is, right now at least, more a problem of distribution than supply, since there is enough food to feed the world's population many times over.

There have to be policy changes, globally, not locally. The world has to work together. To address policy in a global fashion means preventing failed states. Preventing failed states means addressing their food crises. These things are interrelated.

A few other things the world can do...

Diversify plantings. Monocultures (which GE supports) are leaving the environment vulnerable. They do not capitalize on environmental diversity or disparate ecosystems.

Address water shortages. There is a big water crisis looming. It's already affected places in Mexico, China and Africa which now import more [water-in-the-form-of] grain than they grow.

Tackle global warming. The warming of the planet has already contributed to water shortages and climate catastrophes. It will continue.

Restrict the use of grain to produce fuel.

Lots of other things. There is a wealth of information about these issues out there. We have to turn knowledge (which we have) into behavior. That's always the difficult part.