Since 1997 when transgenic Bt cotton was approved for commercial production in China,the area planted with Bt cotton has dramatically increased.In 2012,the total area planted with Bt cotton reached 3.59 million hectares,representing 80% of the total cotton area.The growing of Bt cotton in China for 17 years has brought great benefits to farmers and the environment.Many insect pests,especially cotton bollworms,can cause serious economic damage to cotton.Before the introduction of Bt cotton,Chinese cotton farmers applied large quantities of chemical insecticides for cotton bollworm control,causing serious ecological problems of insecticide resistance,pest resurgence,and environmental pollution.Long-term field surveys showed that with the increasing adoption of Bt cotton,cotton bollworm populations have not only been effectively suppressed in cotton,but also greatly reduced in other non-Bt host crops such as maize,soybean and peanut in the same planting area.The Bt proteins expressed by GM cotton are very specific to the target pest,and has no direct toxicity to non-target organisms,such as the natural enemies of insect pests.Thus,due to the dramatic decrease of insecticide applications on cotton,the population abundances of generalist predators such as ladybirds,lacewings and spiders in cotton fields have gradually increased,providing better natural control for non-target pests such as aphids.In addition,generalist predators usually have great dispersal ability,and increased predator abundance in Bt cotton ultimately promoted biological control services in the whole agroecosystem.However,with the reduction of insecticide application on Bt crops,populations of secondary pests that are not sensitive to Bt proteins may increase.For example,following the start of production of Bt cotton in China,mirid bugs that had been regarded as secondary pests on cotton during last century have progressively increased their population levels and acquired pest status in cotton.This outcome demonstrates that it is not possible to solve all insect pest control problems by using insect-resistant GM crops,but such crops can be involved in an integrated pest management strategy for insect pest management.From an economic perspective,it is estimated that on average at the farm level,Bt cotton increases yield by 10%,reduces insecticide use by 60%,with positive implications for both the environment and the farmer’s health.Papaya is an important fruit crop that is widely consumed as fresh fruit in China.However,it is severely affected by the disease caused by papaya ringspot virus (PRSV).To control this disease and protect papaya industry,PRSV-resistant GM papaya was produced in 1990s in the USA,and it was first commercialized in Hawaii in 1998.In China,a PRSV-resistant GM papaya that was developed by South China Agricultural University was first approved for commercial planting in Guangdong Province in 2006.The percentage adoption of GM papaya in Guangdong increased from 70% in 2007 when it was first commercially planted to 95% in 2012.In addition,GM papaya was grown for the first time on Hainan Island,where 40% of 5 000 hectares of papaya grown was GM.Thus,the total area of GM papaya grown in China reached 6 275 hectares in the whole country.The planting of disease-resistant papaya has provided efficient protection against papaya ringspot virus.As a consequence,chemical application to this crop has been significantly reduced,with the results that the farmer’s income has been enhanced and the environment has been improved.