the GlobalChangeBiology blog

This paper is a critique of Srivastava and Kolady (Current Science, 2016; 110: 3-10) who reported a macro analysis of the benefits of Bt cotton in India using statewide average data. The analysis is in error with respect to the economic benefits, biological underpinnings, and the effects of Bt cotton technology adoption on resource-poor farmers growing rainfed cotton. Viable non-GMO high-density cotton alternatives that increase yields, reduce cost of production, and give higher net average returns were ignored. The authors argue for biotechnology adoption in other crops in India without providing data or analysis Gutierrez A.P., Ponti L., Baumgärtner, J., 2017. A critique on the paper ‘Agricultural biotechnology and crop productivity: macro-level evidences on contribution of Bt cotton in India’. Current Science, 112: 690-693. Full text free to download Trends for cotton yield, pesticide use and the percentage of total cotton growing area planted to Bt cotton.

Cotton with coevolving pests has been grown in India for more than 5000 years. Hybrid cotton was introduced in the 1970s with increases in fertilizer and in insecticide use against pink bollworm that caused outbreaks of bollworm. Hybrid Bt cotton, introduced in 2002 to control bollworm and other lepidopteran pests, is grown on more than 90 % of the cotton area. Despite initial declines, year 2013 insecticide use is at 2000 levels, yields plateaued nationally, and farmer suicides increased in some areas. Biological modeling of the pre-1970s cotton/pink bollworm system was used to examine the need for Bt cotton, conditions for its economic viability, and linkage to farmer suicides. Yields in rainfed cotton depend on timing, distribution, and quantity of monsoon rains. Pink bollworm causes damage in irrigated cotton, but not in rainfed cotton unless infested from irrigated fields. Use of Bt cotton seed and insecticide in rainfed cotton is questionable. Bt cotton may be economic in irrigat...