Published in this month's edition of Nature the findings are the latest from the UK's Farm Scale Evaluations (FSE), a four-year test of GM crops' impact on the environment.
The scientists at the Harpenden, UK-based research station have been studying the effect of an EU-wide ban on a toxic weedkiller called atrazine. They found that growing GM maze had no adverse effects in terms of biodiversity. No longer approved for use by EU farmers because they harm wildlife, atrazine will be phased out by 2006.
"A large reduction in weed numbers was found when atrazine was applied before the maize crop had emerged from the ground. Other patterns of conventional weed killer used were less effective, but still reduced weed numbers more than the weed control practised in the GM herbicide-tolerant maize," said Professor Joe Perry who led the research.
The study found that the amount of wildlife living in fields of GM maize was two to three times higher than those in fields of conventional maze sprayed with atrazine.
One of the problems with growing fodder maize - corn for animal feed rather than for human consumption - is that it requires significant amounts of weedkiller to prevent it being asphyxiated by native weeds.
Non-GM maize is usually treated wtih atrazine. The GM maize studied in the trials was genetically engineered to resist another herbicide, called glyphosate. This means that weed-killer can be sprayed later in the growing season. This allows weeds more time to develop so that their rotting matter and seeds can feed birds and insects.
Full findings of the study by J.N. Perry et al are published in Nature.
In the UK this week the heat has turned up as rumours circulate that Margaret Beckett, the UK Secretary for Environment, Food and Rural Affairs might announce changes in government GM policy. Media reports suggest that she probably will license the UK's first commercial cultivation of a GM crop, a type of corn developed by a unit of Bayer AG, UK.
In a letter to prime minister Tony Blair, the National Trust, The National Consumer Council, Friends of the Earth and six other organisations with a combined membership of 8 million people urged the government to withhold approval of the commercial growing of genetically modified crops, claiming too little is known about the risks.