ngin - Norfolk Genetic Information Network

6 June 2002


1. A summary of research on the environmental impact of Bt cotton in China
2. GM cotton damaging environment


1. A Summary of research on the environmental impact of Bt cotton in China

June 2002
Nanjing Institute of Environmental Sciences the State Environmental Protection Administration of China

Published by Greenpeace, Dayuan XUE


Currently, Bt (Bacillus thuringiensis Berliner) transgenic cotton is the main GMO crop variety in large- scale commercial production in China.

Due to the introduction and popularization of Monsanto’s Bt (transgenic) cotton since 1997, Bt cotton plantings have had a very fast growth in area. In 2000, Bt cotton was grown on up to 1 million hectares, accounting for 30% of cotton production in China. It is estimated that the area planted to Bt cotton has increased to 1.5 million hectares in 2001, on 35% of the total cotton area. Monsanto's Bt cotton accounts for approximately two thirds of the Bt cotton grown, while the several domestically developed Bt cotton varieties account for the remaining one third.

Research conducted during the past few years at four domestic academic institutions shows that Bt cotton is effective in controlling the primary pest of cotton - bollworm (Helicoverpa armigera Hbner) - especially in seedling stage of cotton. However, laboratory experiments and field research also demonstrate that there are adverse environmental impacts associated with the cultivation of Bt cotton. These impacts are summarized below.

1. Although in the Chinese studies there are no significant impacts on predatory natural enemies associated with Bt cotton, there are associated adverse impacts on parasitic natural enemies of cotton bollworm. In Bt cotton fields, researchers have shown a decrease in the ratios of parasitization and eclosion and reduction in the weights of cocoon and adult. Consequently, the populations of parasitic natural enemies in Bt cotton fields are significantly reduced.

2. Bt cotton is not effective in controlling many secondary pests, especially sucking pests. Field experiments showed that the populations of secondary pests such as cotton aphids, cotton spider mites, thrips, lygus bugs, cotton whitefly, cotton leaf hopper and beet armyworm increased in Bt cotton fields after the target pest - bollworm - had been controlled. Some pests replaced bollworm as primary pests and damaged cotton growth.

3. The diversity indices of the insect community, the pest sub-community and the pest-natural enemies sub-community, as well as the evenness index of Bt cotton fields are all lower than those in conventional cotton fields. However, the pest dominant concentration in Bt cotton fields is higher than in the conventional cotton fields. Therefore, the stabilities of insect community, pest sub-community and pest-natural enemies sub-community in Bt cotton fields may be less than those in conventional cotton fields, and the possibility of outbreaks of certain pests in Bt cotton is much higher.

4. Both laboratory tests and field monitoring have verified that cotton bollworm can develop resistance to Bt cotton. Laboratory tests for selection of Bt-resistant bollworm indicated that susceptibility of bollworm to Bt cotton fell to 30% after 17 generations under continuous selection with a diet of Bt cotton leaves. The resistance index of the bollworm increased 1000 times when the selection was continued to the 40th generation. Based on these results, the scientists concluded that Bt cotton would probably lose its resistance to bollworm in fields after the Bt cotton has been planted for 8-10 years continuously.

5. Bt cotton demonstrates excellent resistance to the second generation bollworm and chemical control is not generally needed for the seedling period of Bt cotton. However, the resistance of Bt cotton to bollworm decreases over time, and control is not complete in the third and fourth generations. In fact, farmers must use chemicals 2-3 times to control bollworm, particularly from mid- July to the end of August.

6. Development of resistance of bollworm to Bt cotton has been commonly recognized in China, but there are not yet effective measures to postpone resistance development or to resolve the resistance problem. A high-dose of the Bt toxin protein is considered difficult to obtain, and the refuge mechanism is not easily implemented. In addition, the high-dose assumption and refuge design have theoretical shortcomings.

Complete document can be found at:


2. GM Cotton damaging environment

June 3, 2002
XINHUANET 2002-06-03 22:23:10

BEIJING, (Xinhuanet) -- A genetically modified cotton plant which makes up 35 percent of China's crop, is damaging the environment despite its success in controlling the boll worm pest, according to a report released here Monday.

The plant, Bt transgenic cotton, was harming natural parasitic enemies of the bollworm and seemed to be encouraging other pests, according to the study by the Nanjing Institute of Environmental Sciences (NIES) under the State Environmental Protection Administration (SEPA) at a seminar here. Researchers have seen a significant decrease in populations of the bollworm's parasitic natural enemies.  Bt transgenic cotton, containing anti-bollworm genes from certain bacillus, is in large-scale commercial production in China and the planting area was estimated to top 1.5 million hectares last year, accounting for about 35 percent of the total cotton area, according to the Cotton Research Institute under the Chinese Academy of Agricultural Sciences.

The report says that the diversity index of the insect community in the Bt cotton fields is lower than conventional cotton fields while the pest dominant concentration index is higher.

The balance of the insect community is weaker in Bt cotton fields than the conventional crops as some kinds of insects thriveand this is more likely to cause outbreaks of certain pests, said Xue Dayuan, the NIES expert in charge of the report.  Populations of pests other than cotton bollworm has increased in Bt cotton fields and some have even replaced it as primary pests because the GM plant is slow at controlling those pests, the report says.

Scientists also verified with lab tests and field monitoring that cotton bollworm will develop resistance to the GM cotton and concluded that Bt cotton will not resist boll worm after being planted for eight to ten years continuously.  New GM organisms and products would benefit agriculture and many other industries, but people should always beware of the long-term and underlying impacts on the environment, said Zhu Xinquan, chairman of the Chinese Society of Agro-Biotechnology that jointly hosted the seminar with the NIES and Greenpeace China.

GM organisms will pass new genes borrowed from different species to local plants and creatures through reproduction when it is put into the natural environment, changing the natural gene structures, said Isabelle Meister, an expert from Greenpeace International, the international environmental campaign group.

"The changes are irreversible and the loss is likely to be damaging as the genes in nature, mostly existing in wildlife and some small regional species, are useful for people to develop new species of plants and animals with high quality or against certain disease," she said.

China is a center for diversity of several plants like soy beanand faces the problem of how to protect its original genes from imported GM products, Meister said.

ngin bulletin archive