Eight Years of Bt Cotton in Farmer Fields in China: Is the Reduction of Insecticide Use Sustainable?
The farmers in China's northern and central provinces began adopting Bt cotton in 1997 and in recent years almost exclusively plant Bt cotton. Adopted largely because traditional means of controlling bollworms by spraying insecticides were largely ineffective, the initial large gains in productivity from adopting Bt cotton, which expresses a toxin that can control bollworms, came mostly from sharply reduced levels of insecticide use. Despite the successes during the first years after adoption, there are uncertainties about the future of Bt cotton. On the one hand, the absence of refuges raises the question about whether or not the gains be sustained in the future. On the other hand, it also is a possibility that as Bt cotton acreage spreads, there may be positive externalities that can increase the gains. The overall goal of this research is to examine whether or not the gains from reduced spraying for bollworms that characterized the initial spread of Bt cotton is being sustained almost one decade after its initial adoption. Based on farm level data collected by the authors in 1999, 2000, 2001 and 2004 in 16 villages in Hebei, Shangdong, Henan, and Anhui provinces, our analyses show that insecticides applied to control bollworms instead of increasing as some expected in fact have declined. While the study's results, which are based on socio-economic data from Bt and non-Bt cotton farmers, are not able to pinpoint the exact mechanism that has allowed Bt to maintain or increase its productivity-enhancing effects, they are consistent with a story that suggests farmers, both those cultivating Bt cotton and non-Bt cotton, have been able to continue to reduce their use of insecticides due to lower populations of bollworm that have fallen as a result of Bt cotton area expansion. Moreover, our results are also consistent with the findings that at least eight years of commercialization, if there is any rise in the inherent resistance of bollworms to the Bt toxin, it still has not induced farmers to increase their use of insecticides to control bollworms. The findings from this study have important implications not only for refuge management policy in agricultural sectors of developing countries that are dominated by small, poor farmers that plant a diversified set of crops, but also for those that are interested in the methodologies that have been used to measure the direct and indirect impacts (or externalities) of insect-resistant GM technologies on crop production decisions.