SC - Evolution of food-genetics of food

[CorwynWdwd at aol.com]

In a message dated 3/17/2000 10:45:02 PM Eastern Standard Time, 
LrdRas at aol.com writes:

> << GM foods do to the ecosystem, such as the 
>   decimation of the monarch butterfly population. >>
>  
>  I'm afraid to ask..but...huh?
>  
Of course, all the studies aren't in yet, and I'm sure the GM agribusiness 
people will have counter studies out there, but this pretty much covers it. 
There's lots more out there. The last I heard on a radio report, the GM 
interests suggested that the Monarch caterpillars might try feeding off the 
lower leaves, or the bottom leaves... The Monarch butterflies have as yet to 
comment :-).


Toxic pollen from widely planted, genetically modified corn can kill monarch 
butterflies, Cornell study shows

HOLD FOR EMBARGO: WEDNESDAY, MAY 19, 1999, 2 P.M., EDT
Contact: Blaine P. Friedlander, Jr.
Office: (607) 255-3290
E-Mail: bpf2 at cornell.edu

 
Monarch caterpillars on a milkweed leaf dusted with pollen Photo by Kent 
Loeffler A higher-resolution copy of this photo (1500 x 2100 pixels, 1.5MB) 
is available here. 
ITHACA, N.Y. -- An increasingly popular commercial corn, genetically 
engineered to produce a bacterial toxin to protect against corn pests, has an 
unwanted side effect: Its pollen kills monarch butterfly larvae in laboratory 
tests, according to a report by Cornell University researchers.

Writing in the latest issue (May 20) of the journal Nature, the Cornell 
researchers note that this hybrid crop, known as Bt-corn, has genes from the 
bacterium Bacillus thuringiensis (Bt) spliced into the plant genes. These 
hybrids are very effective against the ravenous European corn borer, a major 
corn pest that is destroyed by the plant's toxic tissue. The engineered corn 
is safe for human consumption. 

Unlike many pesticides, the Bt-corn has been shown to have no effect on many 
"nontarget" organisms -- pollinators such as honeybees or beneficial 
predators of pests like ladybugs. But the Bt-modified corn produces pollen 
containing crystalline endotoxin from the bacterium genes. When this corn 
pollen is dispersed by the wind, it lands on other plants, including 
milkweed, the exclusive food of monarch caterpillars and commonly found 
around cornfields.

Says John E. Losey, Cornell assistant professor of entomology and the primary 
investigator on the study: "We need to look at the big picture here. Pollen 
from Bt-corn could represent a serious risk to populations of monarchs and 
other butterflies, but we can't predict how serious the risk is until we have 
a lot more data. And we can't forget that Bt-corn and other transgenic crops 
have a huge potential for reducing pesticide use and increasing yields. This 
study is just the first step, we need to do more research and then 
objectively weigh the risks versus the benefits of this new technology."

Like all grasses, corn is wind-pollinated, and the pollen can be blown more 
than 60 yards from the edge of cornfields. "Pollen is that yellow dusting 
your car gets on spring and summer days; pollen is everywhere," explains 
Losey. "That's why we are concerned about this problem." 

Other researchers on the study were Linda S. Rayor, Cornell instructor in 
entomology, and Maureen E. Carter, Cornell research aide. 

"Monarchs are considered to be a flagship species for conservation. This is a 
warning bell," says Rayor. "Monarchs themselves are not an endangered species 
right now, but as their habitat is disrupted or destroyed, their migratory 
phenomena is becoming endangered."

In the laboratory tests, monarchs fed milkweed leaves dusted with so-called 
transformed pollen from a Bt-corn hybrid ate less, grew more slowly and 
suffered a higher mortality rate, the researchers report. Nearly half of 
these larvae died, while all of the monarch caterpillars fed leaves dusted 
with nontransformed corn pollen or fed leaves without corn pollen survived 
the study. 

The toxin in the transformed pollen, the researchers say, goes into the gut 
of the caterpillar, where it binds to specific sites. When the toxin binds, 
the gut wall changes from a protective layer to an open sieve so that 
pathogens usually kept within the gut and excreted are released into the 
insect's body. As a result, the caterpillar quickly sickens and dies.

Bt-engineered corn is among the first major commercial successes for 
agricultural biotechnology. Last year, more than 7 million acres of the 
hybrid crop were planted by U.S. farmers primarily to control the European 
corn borer. Before the advent of Bt-corn, this pest was extremely difficult 
to control because it bores into the stalk, where it is protected from 
pesticides. It produces several generations a year. Because it was so 
difficult to control effectively with pesticides, annual losses averaged $1.2 
billion. In contrast,Bt-corn provides essentially total season-long control 
at a reasonable cost without the use of pesticides. At least 18 different 
Bt-engineered crops have been approved for field testing in the United 
States. As of last year, transformed corn, potatoes and cotton had been 
approved by the U.S. Department of Agriculture for commercial use. 

Several factors make monarch caterpillars particularly likely to make contact 
with corn pollen, Losey says. Monarch larvae feed exclusively on milkweed 
because it provides protection against predators. The plant contains 
cardenolides, which are toxic, bitter chemicals that the monarch caterpillar 
incorporates into its body tissues, rendering it unpalatable to predators. 
Milkweed grows best in "disturbed" habitats, like the edges of cornfields, 
Losey notes. 

The butterflies overwinter in Mexico and by the spring begin migrating north. 
The first generation of the year crosses into Texas, other Gulf Coast states 
and Florida, seeking milkweed on which to lay their eggs and feed. By late 
May or early June, the second generation of adults has emerged and heads 
north to areas including the Midwest Corn Belt. Monarch caterpillars are 
feeding on milkweed during the period when corn is shedding pollen, Losey 
says. Thus "they may be in the right place at the right time to be exposed to 
Bt-corn pollen."