The transgenic cotton can resist the cotton bollworm, but the blind animal is quietly elevated
It is about 1.5 centimeters in length. Due to its high degree of color blindness, it can only rely on two tentacles that are highly sensitive to smell to sense the outside world and find food. It is afraid of the sun, likes to stay in the night, work under the shade of moonlight, pierce the needles, suck the young leaves or buds of cotton, and greedily drink.
In May of each year, the cotton in North China begins to enter the growing season. When the temperature reaches above 15°C and the humidity is higher than 60%, the eggs of the monstrous elephants begin to hatch. In the middle and late May, cotton branches and leaves began to grow, and blind monks grew up. Since the large-scale planting of transgenic Bt insect-resistant cotton in 1997, this hemiptera insect has occupied the niche of the bollworm and has become the most important pest in China's cotton fields.
On May 14th, the online edition of the American "Science" magazine published a paper by the team headed by Wu Kongming, director of the Institute of Plant Protection of the Chinese Academy of Agricultural Sciences and director of the State Key Laboratory for Biology of Plant Diseases and Insect Pests. Regional population catastrophic impact mechanism.
Wu Kongming et al.'s study showed that the large-scale planting of Bt cotton effectively controlled the hazards of the second-generation cotton bollworm, and the use of chemical pesticides in the cotton field was significantly reduced, but it also provided a breeding ground for the population of the important insect pest of the cinerea. In the cotton field, an outbreak occurred, and it was derived from the ecological superposition effect of the population, which became the main pest of various regional crops.
Regarding this latest research achievement, both the steadfast opponents of GM technology and the fans of GM technology have given recognition and high praise, arguing that this is the first global GM-related business involving multiple crops and large time scales. Study on Ecological Impact Assessment of Chemical Planting.
The cotton bollworm is gone
Wu Kongming has been studying cotton pests for more than 20 years. Prior to the widespread planting of transgenic insect-resistant cotton, their work focused on the control of red spiders and bollworms. In the early years of the 1990s, due to long-term use of pyrethroid pesticides against Helicoverpa armigera, the insects that like to eat boiled peaches produced terrible drug resistance, and bollworms broke out in large areas in China. In the memory of Wu Kongming, 1992 was a peak. The cotton production in North China was reduced by more than 30%, and the economic loss exceeded 10 billion yuan.
While China is a headache for cotton bollworms, scientists at home and abroad are studying a genetically modified technology and hope that by implanting the genes of a microorganism belonging to the genus Bacillus thuringiensis (Bt) into plants, the crops will have natural insect resistance to the bollworms. . In 1996, the United States began commercial cultivation of Bt cotton. The transgenic crops quickly exhibited good insect resistance and the use of pesticides dropped drastically.
In 1997, the Chinese government formally approved the commercial cultivation of Bt cotton. By the year 2000, the North China provinces, one of the major cotton producing regions in China, had basically adopted the planting of Bt cotton. In 2007, China had 3.8 million hectares of Bt cotton fields, accounting for 69% of the country's cotton acreage.
That is, since 1997, Wu Kongming and his colleagues have started a follow-up study on the impact of the commercialization of genetically modified Bt cotton on China's ecological environment and agricultural economy. Their research scope covers 3 million hectares of cotton fields and 26 million hectares of other host crops planted annually by more than 10 million cotton farmers in North China.
In September 2008, Wu Kongming et al. published the paper in the "Science" magazine for the first time on the basis of field simulation studies and analysis of the agricultural data of Bt cotton in the six northern provinces of China from 1997 to 2007, and it was the prominent position of the cover article. After 10 years of research on the relationship between the evolution of the cotton bollworm population and Bt cotton, the Chinese plant protection experts have clarified that the large-scale commercial planting of Bt cotton destroyed the seasonally multi-host transformed food chain of cotton bollworm in North China, and compressed cotton bolls. The niche of the insect not only effectively controls the damage of cotton bollworm to cotton, but also highly inhibits the occurrence and harm of cotton bollworm in crop fields such as corn, soybean, peanut and vegetables. This study laid a foundation for explaining the regulatory mechanism of transgenic insect-resistant crops on the target population evolution and the sustainable control of cotton bollworm.
However, Wu Kongming et al. pointedly pointed out at the time that although transgenic Bt cotton has brought about a new idea and new tool to control pests and diseases, it is still unclear about its long-term widespread impact on ecology and economy.
Blind
In this long follow-up study, there is also a monitoring of secondary pests in cotton fields.
“The cotton field is a complex ecosystem and there are more than 300 pests that live in it. Under different planting patterns, different organisms will evolve into major pests.†Wu Kongming said, “One of our key researches is to observe After the commercialization of transgenic Bt cotton, who will make up for the niche position of the cotton bollworm will become the main pest.â€
In the course of long-term patient monitoring, scientists have discovered that a pest called a blind animal is quietly in place. Wu Kongming explained that the omnivorous pests of this species have always been secondary pests in China's cotton fields. In the past, when spraying pesticides to kill bollworms, they were also killed by the way. There is no need for special control.
However, with the large-scale planting of Bt cotton, the dosage decreased by 30% to 40%, while Bt cotton only has control effects against target pests, such as Helicoverpa armigera and other Lepidoptera species, and it is a blind target for non-target pests of Hemiptera. Not controllable. According to Wu Kongming's monitoring of 38 observation sites in six provinces in North China from 1997 to 2008, the occurrence of blind stink bugs in cotton fields showed a significant upward trend with the increase of Bt cotton planting rates. Their monitoring of the degree of destructive damage to cotton, jujube, apple, pear, peach and grape crops at 77 observation sites in North China also showed the same conclusion.