"In the wake of animated debate on genetically modified (GM) crops, the safety of GM crops and issues related to their adoption have been the object of intense research work. When the effect of GM crops on the target species, weeds or pests is considered, a reduction of biodiversity is expected and is necessary for the success of the crop. However, it is the use of non-GM crops that would lead to higher reductions in biodiversity as use of chemicals to assist their disease free growth is often more toxic and persistent in the environment. Reportedly in a systematic study of pre-and post adoption of Bt cotton in China, a marked increase in abundance of generalist arthropod predators and a decreased abundance of aphid pests and reduced insecticide sprays were seen. Also evidence showed that predators might provide additional bio-control services spilling over form Bt cotton fields onto neighboring crops.
The government claims that the pest management traits that are embodied in currently commercialized GM crops have led to changes in the use of pesticides that may have impacts on biodiversity. If the planting of GM pest-resistant crop varieties eliminates the need for broad-spectrum insecticidal control of primary pests, naturally occurring control agents are more likely to suppress secondary pest populations, maintaining a diversity and abundance of prey for prey for birds, rodents and amphibians.
According to the government, GM crops are favorable to the environment, firstly because GM crop help farmers reduce pesticide applications. It has been reportedly estimated that widespread use of GM crops has reduced the amount of pesticides use by nearly 1.3 billion pounds, thus reducing the environmental footprint. Secondly, biotech crops require less fuel and less tillage. GM crop-related carbon dioxide emission savings were equal to the removal of 12.4 million cars from the road for one year.