Optimal Refuge Policy for Bt Cotton
Attributes
Medium: Animals, Plants and/or Others
Country: China
Analytical Framework(s): Economic Analysis
Unit(s): Discounted Cost
Study Date: 2005
Publication Date: 2006
Major Result(s)
Study Note: This study discussed the theory behind the nature of steady states, their stability properties, and circumstances under which these steady states will emerge as long run solutions to the dynamic problem. This study also explored the importance of the impact of fitness cost on an optimal refuge strategy. Empirically, the impact of the natural refuge crops (other host crops of the pest than cotton that are planted adjacent to cotton) on the development of the resistance of target pest was considered.
Study Details
Summary: The development of genetically modified (GM) crop varieties has arguably been the most successful application of agricultural biotechnology research to date. However, biotechnology is a double-edged sword. Behind the great success lies a lot of concerns about the negative impact of GM crops. One of the major concerns is the buildup of the resistance in pest populations. Even though refuge policies have been implemented in most of the countries to manage the development of resistance, all previous empirical analyses have only focused on the United States. There is very little empirical work that has focused on other countries, especially developing countries. The overall goal of this study is to analyze, theoretically and empirically, the optimal refuge policy to manage the buildup of resistance in a developing county. To narrow the scope of the research, Bacillus thuringiensis (Bt) cotton in China was used as a case study.
Site Characteristics: China is leading the developing world in the use of transgenic crops for battling pest infestations. In part due to the introduction and popularization of Monsanto's Bt cotton in 1997 and the extension of the nation's own Bt varieties developed by the Chinese Academy of Agricultural Sciences, Bt cotton cultivation has grown quickly. In 2004, Bt cotton in China comprised more than 40% of the total Bt cotton in the world. Moreover, Bt cotton is so popular that cotton-growing households in a number of regions of northern China plant almost exclusively Bt cotton. Hence, the size and the concentration of Bt cotton cultivated in China make it an important place to study refuges. Unlike other Bt-adopting countries in the world, in China there has been a conscious choice to opt for a no-refuge policy, despite the fact that there is an active debate on the subject. Some scientists believe that China does not need special non-Bt cotton fields as a refuge because most crops that are grown during the summer/autumn season at the same time as cotton such as maize, soybean and peanuts also function as natural refuges for the cotton bollworm (CBW). However, others argue that in cotton-planting areas where cotton is the only host plant of the CBW, selection may be occurring and hence refuges may be needed, especially given the past propensity of the CBW to evolve resistance in a relatively rapid manner to other conventional insecticides (e.g. organophosphates and pyrethroids).
Comments: Theoretically, this study generalized the discussion of the impact of fitness cost on final equilibrium. This study first discussed the circumstance under which steady states will emerge as long run solutions to the dynamic problem, and the nature of the steady states. Empirically, this study considered the impact of natural refuge crops on the buildup of the target pest's resistance and the optimal refuge policy.