NOTE: Note the sizeable gap in the article between the hype of Chris Leaver, a GM plant scientist who's been a paid consultant for GM corporations and the caution of Michelle Marvier who was part of the team that atually carried out the study. Either way the findings are a powerful argument for non-pesticidal management of cotton and maize - an approach that makes not only environmental but powerful economic sense for resource poor farmers.
EXTRACTS: "This study cannot detract from the fact that large scale planting of GM crops is a significant threat to biodiversity. Sustainable and environmentally-friendly alternatives to GM crops already exist. But these are being sidelined by the massive GM push by biotech companies." - Kirtana Chandrasekaran
"If people have in the past done crop rotations to control certain insect pests - as they have in maize - Bt technology can allow them to stop doing those rotations and that could encourage more [environmentally damaging] monocultures." - Dr Marvier
"For field maize here in the US there weren't a lot of insecticides being used to begin with. You could make an argument that the proper comparison is to maize grown without insecticide," - Dr Marvier
Insecticide study shows GM benefits
James Randerson, science correspondent
The Guardian, June 7 2007
Genetically modified cotton and maize with a built-in insecticide is better for the environment than conventional crops sprayed with insecticide, according to research that pulled together data from 42 different studies conducted across the world.
The researchers found that fields of GM crops had considerably more biodiversity because the insecticide in the plant is less harmful to "non-target" insect species. However, when compared with conventional plants that were not sprayed with insecticide, the GM varieties did have a slight detrimental effect on non-target insects.
"If you want to have decent yields from maize and cotton you often have to protect the crops against insect pests. This paper shows clearly that GM ways of doing so are less damaging to insect wildlife than the use of chemical insecticides," said Chris Leaver, a plant scientist at Oxford University, who was not involved in the research.
The research pulled together studies which compared the abundance of invertebrates that do not affect the crop in fields of GM and conventional varieties. All the GM types were so-called Bt crops, meaning that they had an extra gene for an insecticide protein that is found in bacteria. The insecticide itself is widely used even by organic growers who spray the dried bacteria on their crops. The gene is expressed in the GM plants so any of the target insects that eat it are killed.
The 42 studies were from countries including the US, China, India, Australia and European nations. Some were obtained from the US Environmental Protection Agency under the Freedom of Information Act.
"The answer you get about whether Bt crops are having side-effects on the environment depends on what you compare them to," said Michelle Marvier at Santa Clara University in California, who was part of the team who published the study in Science magazine. "If you compare them to insecticides they come out looking pretty good."
Growing cotton typically requires insecticide and the crop is responsible for around a quarter of the world's insecticide use, so the results suggest that using GM cotton would have benefits for biodiversity. "It's cutting down insecticide use significantly. It is cutting down death due to misuse of insecticides, particularly in China and it is improving yield," said Prof Leaver.
But that may not always be the best comparison. "For field maize here in the US there weren't a lot of insecticides being used to begin with. You could make an argument that the proper comparison is to maize grown without insecticide," said Dr Marvier. In that comparison, GM maize comes off slightly worse in terms of harming non-target species.
Kirtana Chandrasekaran, a food campaigner at Friends of the Earth, said that the focus of the paper is too narrow. The major effect on biodiversity she said was through monoculture farming, and she said GM varieties encourage the shift to monocultures.
"This study cannot detract from the fact that large scale planting of GM crops is a significant threat to biodiversity," she said. "Sustainable and environmentally-friendly alternatives to GM crops already exist. But these are being sidelined by the massive GM push by biotech companies."
Dr Marvier said there was some weight to the monoculture argument. "If people have in the past done crop rotations to control certain insect pests - as they have in maize - Bt technology can allow them to stop doing those rotations and that could encourage more monocultures," she said.
Prof Leaver said that one strength of the paper was that it took the emphasis off specific individual studies. "Everyone will take anecdotal examples ... I think enough experimental data has been accumulated to draw empirically based conclusion, as opposed to arguing on the basis of anecdotal hand-picked examples," he said.
"When you do a quantitative analysis everything gets weighted in an objective way ... it allows for a more objective analysis," said Dr Marvier. "There has been a lot of speculation so anything that pulls data together across a lot of studies is very useful."