By the end of the century, the earth's population will rise from the current 6.7 billion to 10 billion. We will have to face a huge conundrum: how to solve the problem of eating more and more people without destroying the environment?
Water and land are limited, which determines that we cannot expand the area of arable land indefinitely in order to increase production. There is only so much land, production must be increased, and the amount of water used must be reduced. And that's not the only trouble. Environmental change is also a thorny issue: some places experience flooding, while others face drought, and crops have to fight new pests and diseases.
Therefore, improving the efficiency of land cultivation, introducing more beneficial water use policies, improving integrated pest control, reducing harmful interventions to the environment, and developing a variety of new crops have become important goals for many countries. These strategies must be evaluated in terms of environmental, economic and social impacts – the three pillars of "sustainable agriculture".
Defining "GMO"
"Transgenic" differs from traditional "genetic modification" in two main ways: first, transgenic methods introduce genes of a definite nature into plants; second, these genes can come from any species. In contrast, most of the genetic modification methods of traditional agriculture (such as artificial selection, interspecific transfer of genes, random mutations, marker gene selection, and xenografting) introduce genetic properties into crops are unclear. Sometimes, traditional methods also transfer genes from one species to another, as exemplified by gene transfer between wheat and rye, barley and rye.
According to 2011 data, by 2008, 30 genetically modified crops had been planted in 25 countries and 1.2 billion hectares of land, of which 15 were developing countries. By 2015, 120 genetically modified crops (including potatoes and rice) will be grown globally, half of which are developed by national institutions in Asia and Latin America, producing crops that are mainly supplied to their respective domestic markets.
Safety evaluation
The scientific community generally recognizes the safety of genetically modified foods available on the market. Over the past 14 years, about 800 million hectares of land worldwide have been commercialized with genetically modified crops. To date, these crops have not had any negative effects on health and the environment. Both the National Research Council and the European Union's Joint Research Centre believe that our existing body of knowledge is sufficient to assess the safety of genetically modified foods.
Many studies have shown that GM crops do not have more "unintended consequences" on the environment and health than conventional crops. However, this does not mean that every GM crop behaves as friendly as commercially available GM goods. Every new crop that has been modified, whether genetically modified or traditionally genetically modified, can have some "unexpected" consequences. In the United States, GM crops must be evaluated in the "problem-specific analysis" style of 3 government agencies, while traditional genetically modified crops are not subject to these regulations.
Today, however, only hazardous substances found in foods that are traditionally bred are registered. For example, people once used traditional methods to screen a new kind of celery, which contains a large amount of psoralen, which can repel insects. However, some farmers developed a severe rash after harvesting this celery. This is known as the "unintended consequence".
Insect-resistant crops
"Great products that can really replace chemical insect repellents have emerged, some of which have been put into use and with great success; others are still being tested in the lab; and some of them are still just budding ideas in the minds of imaginative scientists, waiting to enter the lab." These new products, no matter what stage they are in, have a common label: biotechnology. Scientists have developed these new methods based on their understanding and understanding of the body and physiology of pests. Entomologists, pathologists, geneticists, physiologists, and biochemists have come together to contribute their wisdom and inspiration to create a new kind of biocontrollery. (Rachel Carson, 1962)
In the 1960s, a book called Silent Spring made many ordinary people aware of the consequences of pesticide abuse on the environment and human health. Even today, there are still thousands of pesticide poisonings in California every year. Globally, 300,000 pesticide-related deaths occur each year.
Reducing the use of broad-spectrum insect-resistant pesticides was one of the reasons for the birth of the first batch of genetically modified crops. Corn and cotton are genetically modified to make a protein that kills important pests such as caterpillars and beetles that harm these crops. The gene that makes this protein comes from Bacillus thuringiensis (Bacillus thuringiensis) in the soil. Bt toxin can be said to be a "potent poison" for many pests, but it has no effect on most beneficial insects and other organisms, and it is harmless to humans.
Sensitive insects that eat Bt crops are killed by Bt toxins. This means that Bt crops can be very effective in controlling pests hidden inside plants, as well as those that cannot be completely killed by pesticides, such as the European corn borer (Ostrinia nubilalis) that burrows into the stem and the cotton red bollworm (Pectinophora gossypiella) that hides in cotton balls.
In 1996, Bt crops were officially commercialized, becoming the second most widely grown GM crop. Prior to this, Bt toxin had been used as a biopesticide for many years. There are some people who still use this pesticide to this day, including growers of organic produce. The fact that humans have been exposed to Bt pesticides for decades has led the U.S. Environmental Protection Agency (EPA) and the U.S. Food and Drug Administration (FDA) to have a wealth of materials to evaluate the safety of Bt crops before approving them for marketing. In addition, scientists have done a large number of toxicity and allergy experiments using a variety of Bt toxins in nature. Based on experimental results and long-term accumulated data, people have concluded that Bt crops, like conventional crops with Bt pesticides, have no negative impact on human and animal health and the environment, and are safe.
Growing Bt crops reduces the amount of chemical pesticides used and thus has a positive effect on the environment and the economy, which is essential for the sustainable development of agriculture. With Bt cotton as the center, a complete pest monitoring system has been established in Arizona, USA. The system has been in operation for more than a decade and is still very effective today. From 1996 to 2008, Arizona reduced pesticide use by 70 percent, saving $2 billion.
A recent study also found that it's not just growers of this genetically modified crop who reap the economic benefits from Bt corn. In 2009, 22.2 million hectares of land in the United States were planted with Bt corn, accounting for 63 per cent of the total corn cultivation area in the United States. It is estimated that over a 14-year period, corn growers in Illinois, Minnesota, and Wisconsin have cumulatively benefited $3.2 billion, of which $2.4 billion came from growing non-Bt corn. This is due to the fact that the cultivation of Bt maize has created a regional suppression of the European maize borer, reducing the harm of this major pest to ordinary maize. Another comparable estimate is that Iowa and Nebraska corn growers benefited a total of $3.6 billion, of which $1.9 billion came from non-Bt corn. These data further confirm the idea of previous studies that growing genetically modified crops can benefit a wider range of people beyond growers.
Growing Bt crops is also in line with another important goal of sustainable agriculture, which is to increase biodiversity. The scientists analyzed 42 field experiments and found that the fields where Bt crops are grown are richer than non-Bt crops (such as insects, spiders, mites, and other species that are not specifically harmful to Bt crops). The conclusion that the cultivation of genetically modified crops can enrich the biodiversity of the fields sets a baseline for the use of insect-resistant pesticides, and as of 2005, 23 per cent of maize fields and 71 per cent of cotton fields in the United States have used insect-resistant pesticides in accordance with this baseline.
In developing countries, Bt crops have also shown its benefits. For example, genetically modified rice and cotton have saved farmers in countries like India significant pesticide spending. A 2005 Study of "Ready-to-Commercialize" Transgenic Rice in China showed that pesticide-related injuries also decreased as pesticide use decreased.
However, while Bt cotton has effectively controlled the outbreak of bollworms in China, other pests that cannot be killed by Bt toxins are becoming increasingly a headache. This further illustrates the need for Bt crops to be used in conjunction with other insect resistance methods. Arizona, USA, has developed a comprehensive pest control system, and farmers use narrow-spectrum insecticides to deal with major pests that are not afraid of Bt toxins. Narrow-spectrum insecticides can protect other beneficial insects. Farmers use dieting inhibitors against pests such as grass blind bugs (Lygus hesperus) and insect growth regulators against tobacco meal lice (Bemisia tabaci).
Pesticides, whether organic, synthetic or genetically engineered, can make pests resistant. Repeated spraying of Bt pesticides on traditional vegetable crops (non-GMO) has allowed the cabbage moth (Plutella xylostella) to evolve resistance to Bt toxins.
This reflects a phenomenon that is extremely common in agriculture: pests evolve resistance in the face of higher selection pressures. So why, after more than a decade, Bt crops still maintain insect resistance? The answer is due to biodiversity. If farmers mix Bt crops with non-GM crops, plants that do not produce Bt toxins can help slow the development of resistance.
Those who watch Bt crops lose their effectiveness are mostly not taking advantage of the benefits of biodiversity. An example is the Indian farmers who grow Bt cotton, who do not leave enough space for non-Bt cotton, and the cotton red bollworm gradually develops a very strong Bt resistance. In Arizona, usa, farmers have been using biodiversity planting strategies from 1996 to 2005, where cotton bollworms do not develop Bt resistance.
The United States has written off Bt cotton with only a single Cry1AC toxin. Now, their Bt cotton carries at least two insect toxins. The new Bt cotton or Bt grain contains more than two toxins, which can both delay the development of resistance and expand the spectrum of pest killing. There is a new Bt insect resistant cotton that can produce 5 Bt toxins, of which 3 kill moths and 2 specifically kill beetles.
Although biodiversity cultivation strategies have slowed the emergence of resistance, this approach also has its limitations. For example, not all farmers will do what experts say. An alternative anti-insect strategy is to release sterile pests into the field to mate with insects that develop resistance.
From 2006 to 2009, Arizona introduced this approach into their "integrated" pest control program. Pesticide spraying was eliminated, and the killing rate of cotton red bollworm in Arizona reached 99%. The success of a comprehensive, integrated pest control strategy confirms Rachel Carson's prediction and provides a roadmap for future agricultural production.