Fears of GM super-pests

Bugs could become resilient to insecticides in GM corn

Concern is mounting in the United States about the environmental impact of genetically modified [GM] corn.

Farmers in the US have traditionally used a natural type of bacteria, known as BT, as an insecticide to keep down pests. Even organic farmers use the spray.

But GM corn has the BT bacteria actually built into it. That might be more efficient - but there are some unfortunate consequences.

New evidence suggests that the GM technique could cause super-pests to evolve.

The idea of a super-pest is quite scary, especially for farmers who depend on crops for their livelihood

Scott Macfarland, National Corn Growers Association

Authorities recommend that farmers set aside 30% of their land as a refuge for traditional insect life, to prevent the super-bug taking hold.

But farmers say the most they can afford to set aside is 20% - otherwise the GM crop becomes uneconomic.

Scott MacFarland of the National Corn Growers Association, said: "The 20% refuge is the threshold where farmers will question whether it is worth investing in the seed."

There has to be a balance between good management practices and profitability.

If management practices require too much refuge, farmers will back away from the technology.

GM foods have built-in insecticides

Rebecca Goldburg, a senior scientist at the New York-based Environmental Defence Fund, said she was concerned about GM corn.

The added feature of the corn - its ability to produce BT toxins that kill insects - is based on a perfectly safe traditional insecticide.

There is considerable concern that the use of genetically-engineered crops with BT toxin in them will lead many insect pests to evolve resistance to the toxins

Rebecca Goldburg, Environmental Defence Fund

Biotechnology has been working on the development of crops that produce BT toxins in the tissue of the crops - with the aim of fighting insect pests and reducing the use of traditional chemical insecticides.

When BT toxins are produced in a genetically-engineered crop, they are produced throughout the tissue of the crop and produced all the time.

Rebecca Goldburg, Environmental Defence Fund

That is in stark contrast to traditional uses of BT insecticidal sprays, which are put on top of crop plants and have a very short life.

BT sprays degrade very quickly with exposure to light, so they are only active against insect pests briefly.

No mandatory review of GM crops in US

Ms Goldburg said: "I am delighted that Europeans are taking a less cavalier attitude towards the development of GM crops than has been taken in the United States.

I do not think that, in the US, we are doing enough to protect the environment and human health from the risks associated with genetically-engineered crops.

Rebecca Goldburg, Environmental Defence Fund

There is no mandatory review for food safety of genetically-engineered crops in the US although Monsanto, one of the major companies producing GM crops, says that all their crops have been properly tested by the American authorities.

However, Ms Goldburg insisted the truth was not that simple.

"When it comes to food safety in the United States, most genetically-engineered crops do not get a hard look by government agencies," she said.

Most crops only receive a voluntary review by the US food and drug administration. There is no mandatory review for food safety of genetically-engineered crops.

There are now movements in the US to have labelling of genetically-engineered foods.