Soybean has been cultivated in southern Latin America since the 1980s. The use of genetically engineered seeds and rising soybean prices have reinforced the trend for soybean monoculture in the region. A soybean field in Canindeyú，eastern Paraguay with erosion curves. Photo：E. Dimpl

Table 1：Estimated global distribution of transgenic crops

The majority of the world’s plant genetic resources are located in tropical and sub-tropical regions and therefore in today’s developing and emergent countries. It is primarily small farmers who preserve and take care of these resources and the related agricultural diversity. As genetically modified crops have also been cultivated in these regions for some 12 years now，the question of their influence on agrobiodiversity arises. Is the impact of genetically modified crops on biodiversity beneficial，detrimental or neutral？We shall use the examples below to discuss this.

An estimated 40 percent of the global acreage of transgenic，i.e. genetically modified（GM），crops is to be found in developing and emergent countries，and，in fact，almost exclusively in just six countries：Argentina，Brazil，China，India，Paraguay and South Africa. Four crops account for 95 percent of all transgenic varieties planted：soybean，maize，cotton and canola（see Table 1）. They are grown for industrial purposes or as animal feed. Until now，only two geneticallyinduced traits have gained commercial importance：herbicide tolerance（HT）in crops and pest resistance through insertion of a gene from the bacterium Bacillus thuringiensis（Bt）.