Impact of IPM and transgenics in the Chinese agriculture

Abstract

The cultivation of transgenic pest-resistant crops may reduce pesticide application, improve production and increase economic benefit. Breeding and planting transgenic pest-resistant crops is expected to be a promising way to control pests. Pest-resistant transgenic researches in China began in the early 1990s. In 1992, China developed the country's first Bt protein gene (CryIA gene) with the intellectual property right of its own. Up till now, the exogenous genes, such as Bt protein gene, trypsin inhibitor gene (CpTI gene), etc., have been transformed into cotton, and more than 50 commercially approved transgenic cotton varieties were developed. Since the 1970s, with the widely uses of chemical pesticides in cotton production, the pesticide-resistance of cotton bollworm (Helicoverpa armigera (Hübner)) dramatically enhanced. Cotton acreage in China declined from 6.835 million ha in 1992 to 4.985 million ha in 1993. In subsequent years, cotton bollworm seriously occurred every year. Since 1998 the adoption of insect-resistant varieties has effectively controlled the outbreak of cotton bollworm. Since the late 1990s, the cultivation area of transgenic insect-resistant cotton in China has been rapidly expanding, and its proportion in the total domestic cotton planting area has been increasing year by year. In 1998, transgenic insect-resistant cotton began to be planted in the Yellow River valley, and that year's acreage reached 240,000 ha, only 5.4% of the total cotton planting area; The planting area increased to 647,000 ha, 1.2 million ha, 1.933 million ha, 1.867 million ha, 3.067 million ha, and 3.104 million ha in the years 1999-2004, accounting for 17%, 31%, 40%, 45%, 60%, and 50% of the total area, respectively. The planting area of domestic transgenic insect-resistant cotton accounted for 30%, 60%, and 70% in the years 2002-2004. Due to the cultivation of transgenic insect-resistant cotton, pesticide application in China reduced by 123,000 t and cotton yield increased by 9.6% during the three years 1999-2001. Currently, almost all of the planted cotton in Hebei, Henan, and Shandong Province is transgenic insect-resistant cotton. In the Yangtze River valley, transgenic insect-resistant hybrid cotton holds the dominant position and its planting area has been growing in the past years. So far, the total planting area of transgenic insect-resistant cotton in China has reached 4.667 million ha, with an average income of 2,130∼2,400 RMB Yuan/ha. Annual reduction in chemical pesticide application reaches 20,000∼31,000 t, equivalent to 7.5% of China's annual total production of chemical insecticides. Breeding of transgenic insect-resistant rice in China developed quickly in the past years. To date, CryI, CpTI, and GNA genes, etc., have been transformed into the rice, and some insect-resistant rice varieties (strains) were developed in China. They can be used to suppress rice insect pests such as Chilo suppressalis (Walker), leafrollers, and brown planthopper. Researches showed that the adoption of transgenic insect-resistant rice can reduce 70∼80% of insecticide application and would not affect the rice biodiversity. From recent years' field trials in Hubei and Fujian, indicated that insecticides were seldom used throughout the growing season and rice yield can increase by 12%. So far, the safety evaluations and experiments on the commercial production of transgenic insect-resistant rice have not yet showed any significant security issues. However, as rice is the main food crop in China, the application for commercialization of transgenic rice has never been approved. In addition to cotton and rice, the insect-resistant transgenics for wheat, soybean, maize, and other crops have being made in China. China has imported some of the transgenic crops and resulted in certain impacts. For example, due to the low production cost and better quality, the transgenic soybean of the United States exhibits the obvious economic advantages. The import of transgenic soybean of the United States resulted in the serious stock of domestic soybean production, and undermined the economic interests of Chinese farmers. So far, the most significant negative impacts for planting transgenic insect-resistant crops, in particular cotton, are the outbreak of secondary pests and the impairment of arthropod community, etc. Due to the problems of planting transgenic insect-resistant crops, such as the narrow insect-resistance spectrum, the increased resistance of insect pests to transgenic crops, the possible outbreak of secondary insect pests, and the potential environment and biodiversity risks, it is necessary to follow IPM principles and combine the other control measures. Chinese scientists have summarized the practical problems in planting transgenic insect-resistant crops and explored various IPM measures, such as resistance management, intercropping, seed purifying, protection of natural enemies, etc., to address these problems. The IPM measures have being implemented in China.