Long-term impact of Bt cotton: findings from a case study in China using panel data

Abstract

Bt cotton has been cultivated in China for a decade. Studies have been conducted to assess theimpact on productivity and pesticide use. Limitations of these studies are the short time period considered and the reliability of data. This paper presents findings from monitoring 150 Bt cotton farmers in Shandong province in 2002 and 2005. Descriptive analysis reveals that pesticide use increased while seed price and Bt toxin concentration decreased. The Bt variable was consistently insignificant in the estimated production function with damage control specification and a fixed effects model. There is indication that poor standards in Bt varieties have caused this result. Due to market imperfections and emergence of a largely unregulated seed market for genetically modified crops, Bt toxin levels may be below the threshold required to effectively control target pests. Furthermore, rising cotton prices may have created additional incentive to increase pesticide applications. The emergence of secondary pests calls for further in-depth studies that should include local agro-ecological conditions. Our results indicate that farmers with more experience in Bt cotton cultivation apply less pesticides, confirming the findings of other studies that farmer knowledge and understanding of the Bt technology is an important condition for its success.

Farmer and Market Interactions in using Biotech Cotton Varieties and Seed. A Case in Northern China

“…In terms of the evolution of Bt cotton effectiveness and profit, 29.2 per cent of all farmers considered that there was a downward trend. As regards the general satisfaction reported in the early 2000s (Pray et al, 2002), but subsequently challenged (Pemsl, Volker, Wu, & Waibel, 2008), our results quantify the decline in the positive opinion of Bt cotton.…”

“…The use of Bt cotton was so quickly generalised that a comparison with non-Bt cotton has become difficult: farm holdings are somewhat too uniform to demonstrate any differentiation in performance. Nevertheless, Chinese farmers might have reason to question the real performance of Bt cotton, as it was found that all Bt cotton varieties used by farmers had low concentrations of Bt toxins, jeopardising their effectiveness in controlling pests (Pemsl, Voelker, Wu, & Waibel, 2011). Low concentrations of Bt toxins have also been observed in hybrids in YaRV (Xu, Fok, Bai, & Zhou, 2008).…”

Rice Production without Insecticide in Smallholder Farmer's Field

“…Moreover, these practices may induce outbreaks of other rice pests by disrupting natural enemy activity. Insecticides induce the outbreaks of secondary pest (Pemsl et al, 2011) and affect natural enemy abundances in fields (Dutcher, 2007).…”

Managing maize under pest species competition: Is Bt (Bacillus thuringiensis) maize the solution?

“…Such occurrence of secondary pests would require additional spraying with conventional broad‐spectrum insecticides, which may erode (at least) some of the benefits of GEIR crop technology (Pemsl et al. ).…”