Big yielding, nutrient-packed crops that survive drought, salty water, even floods: the visionary dreams of genetic engineers. Back in today’s world, the vast majority of GMOs have one of two traits, herbicide tolerance or pest resistance. How helpful are they?
 | Chemical Crop CureThai farmers spraying their rice field with herbicides. Certain GM crops make such treatment even more effective (Photo: Reuters) |
Farmers hiding behind face masks don’t inspire confidence in the safety of their crops. The chemicals used to fend off bugs and diseases are so toxic that an estimated three million people in the developing world are poisoned every year, says the World Health Organization.
Unfortunately, most modern crops need chemical help to survive. Traditional crops did resist many pests and fungi, but generations of breeding and refining have produced highly productive, but fragile new varieties.
Improving these high-yield crops through genetic engineering has become the biggest application of GM technology in agriculture. The idea was first realized in 1996, when the agrochemical company Monsanto commercialized "Roundup Ready Soybeans". These genetically altered soybeans were unharmed by the company’s weed killer "Roundup".
The "Roundup" line of herbicides had been on the market since the 1980s, and soon became the most successful brand of herbicides worldwide. But glyphosate, the product’s main agent, proved so efficient that farmers had a hard time using it. If not applied correctly, crops withered away just like every other weed in the field.
Weed killer
To avoid such casualties, Monsanto developed the Roundup Ready crops, containing a gene naturally found in fungi and bacteria. The new gene allowed all Roundup crops to break down the herbicide into its non-hazardous components. The new weed killer was a huge commercial success.
In 2002, more than 80 percent of all soybeans grown in the United States were Roundup Ready. Fired up by burgeoning sales, Monsanto released Roundup Ready canola and cotton in 1997, followed by corn in 1998.
Yields increased significantly, but Monsanto’s initial claims that herbicide tolerant crops would also help reduce the use of herbicides remain contested. A 2008 report from Friends of the Earth found that between 1994 and 2006, the amount of glyphosate applied per acre of soybeans had risen by more than 150 percent.
Friends of the Earth, Greenpeace and other environmental groups also criticize the de facto monopoly built by Monsanto, the owner of patents on both Roundup and Roundup Ready soybeans. Monsanto sets the price for both the herbicide and the crop. Farmers in the U.S. say that Monsanto violates antitrust laws, an allegation that is currently being reviewed by the U.S. Department of Justice.
German conglomerate Bayer CropScience has been working on an alternative to Roundup Ready crops for years. Their LibertyLink crops – due to be introduced in 2009 – have proven resistant to another important herbicide called glufosinate. Ecologists might not like it, but this development leaves farmers with more weed killing options.
With millions of hectares growing Roundup Ready crops, certain weeds are starting to develop herbicide resistance. Sometimes, the immunity is transferred to other species by cross-pollination, especially if weed and crop are related.
In other cases, the repeated use of the same herbicides makes weeds evolve and improve their resistance mechanisms. A study conducted by the Weed Science Society of America in 2008 shows that to date, six weed species have developed resistance to glyphosate worldwide.
Protecting against pests
But even if weeds do not develop resistance, farmers still have to face insects, rodents and other animal pests. The GMO Compass, an online database for genetically modified organisms and food, states that every year insects destroy about 25 percent of crops worldwide.
Nature, nudged along by inventive scientists, has the perfect solution: Bacillus thuringiensis (Bt), a bacterium occurring naturally in the soil, which produces proteins and spores that kill most pests. Even better, Bt-based pesticides only kill when ingested and have little or no effect on humans, wildlife, pollinators, and most beneficial insects.
Since the 1930s, farmers have sprayed Bt pesticides to fend off tobacco budworms, cotton bollworms, or corn borer larva. But the pesticides weakened when exposed to sunlight or were simply washed away by rain, making them expensive and inefficient.
Genetic modification solved that problem. Biotechnologists started identifying specific strains of Bt that kill specific insects. They isolated the gene that produces the lethal protein and inserted it into affected crops. The plant now produces the toxin that kills its enemies.
These toxins are not washed away by rain water and only those insects that really eat the plants are affected. Studies from Australia´s Commonwealth Scientific and Industrial Research Organisation (CSIRO) and the Chinese Institute of Plant Protection show that both the use of insecticides and the amount of pests decreased in Bt cotton fields compared to plantations growing conventional cotton. Bt cotton, the CSIRO study finds, reduced the use of pesticides by 64 percent compared with conventional non-GM cotton in Australia.
Stacked genes
However, pest resistant crops face the same problem as herbicide tolerant varieties. Natural evolution permits insects to build up resistance to Bt. So far, only the diamondback moth is known to have developed resistance to Bt.
Conventional tools such as crop rotation or the occasional use of chemical insecticides are necessary to maintain a balance.
But biotechnology doesn’t stop there. With its latest creation, Monsanto takes genetic modification one step further. By "stacking" various genetic traits in one plant, the company created a corn species that is Roundup Ready and Bt resistant to rootworms at the same time.
Other companies are following suit and creating the next generation of GM crops, stacked with various modifications to make them ever more robust. It looks like the ultimate, indestructible 'super plant' is just around the corner.
The question is how long it will take nature to respond with a super weed or a super pest?
editor: Bettina Fachinger
publishing date: October 16, 2009
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