Another Bt cotton success story

September 2012

Picture of agricultural labourers working in a cotton field  Andhra Pradesh, South India
Agricultural labourers working in a cotton field Andhra Pradesh, South India.
Picture by jankie on Flickr
The 'success' or 'failure' of Bt cotton, now widely grown in India, continues to be steeped in controversy.

Biotech industry trials and short-term economic studies on these GM crops with built-in insecticide describe their performance in glowing terms. However, serious doubts about the long-term impacts remain.

A new study of Bt cotton, aiming to address the “uncertainty about longer term effects”, has been published.

Using data collected from over 500 “smallholder farmers” in four principal cotton-producing states, German agricultural economists Karthage and Qaim examined crop production economics and household living standards. They compared “early” experiences during the first four years of Bt cotton cultivation (2002-2004) with “subsequent, “late”, experiences (2006-2008).

Results “showed that Bt has caused a 24% increase in cotton yield per acre through reduced pest damage and a 50% gain in cotton profit among smallholders ... These benefits are stable ...”. They further showed that “Bt cotton adoption has raised consumption expenditures, a common measure of household living standard, by 18% during the 2006-2008 period”.

Bt cotton is clearly a resounding all-round success in India, sustainably helping the majority of farmers (the smallholders) to produce more cotton with less pesticides, and giving them much-needed increased spending power.

Or, is it?

Commentators have raised significant concerns about key aspects of the study.

For example, there are signs that the description of the farmers selected to provide the data was misleading.

Kathage and Qaim's definition of “smallholder farmer” is ownership of 11.48-15.07 acres: the official definition of “smallholder farmer” which everyone else uses is ownership of only 5 acres or less. The majority of farmers in India fall within the official definition of smallholder: they clearly weren't the ones studied by the German economists.

It is rightly noted that weather conditions were stable during the period of study. However, irrigation is not mentioned. Bt crops are notoriously unsuccessful in the absence of irrigation: the farmers who achieved a 24% increase in yield must have had it. Irrigation schemes are not the norm in India, especially on smaller farms.

The lynchpin of the German paper is a statement that the higher yield recorded for Bt hybrids was due to “more effective pest control and thus lower crops losses”. All other confounding factors are dismissed. As GM Watch pointed out, no evidence is provided which actually substantiates this cause-and-effect claim, and the logic seems to be wanting.

In particular, the cotton pests which the Bt toxin was deemed to be controlling so successfully were not examined.

No information was collected regarding pest pressure. However, it is acknowledged that bollworm incidence in India has been low since 2002. If pest pressure was low and there weren't many insects for the Bt to kill, how did the technology manage to contribute to yield?

Moreover, no data was presented regarding the hybrids or varietal seed actually being grown.

Consider what was was being planted in Indian cotton fields during the period of study.

In 2002, three GM hybrids were introduced in India. By 2008, there were 880 strains available. The yield potential of these must have varied, as would the level of generation of the Bt toxin.

During 2002-2008, Government control of GM seed availability improved, and Bt adoption increased from 38% to 99% with little availability of non-Bt supplies for comparison by the end of the study.

Notoriously in India, an unknown amount of black-market 'Bt' seed of dubious origin and quality has been in circulation. Both the conventional and Bt stands may have been extensively contaminated by undetermined plants strains and unregulated artificial DNA constructs.

In a nutshell, who knows what cotton plants were actually being grown and studied from year to year. What is certain is that the nature of the crops in the cotton fields changed radically during the course of 2002-2008. The presence of Bt toxin there is a very small part of the whole picture, and couldn't possibly be the only factor affecting crop yield.

Attributing increased spending power solely to the growing of Bt cotton suffers all the same lapses in logic as the Bt-yield claim. For example, the farmers must have been growing lots of crops besides cotton: no data are presented to indicate the extent of these, their success, nor any impact they had on farmers' bottom line.


Although compromises in data collection are inevitable, these must be acknowledged, and the conclusions based on them appropriately qualified. That this wasn't done with regard to such key factors as irrigation, pest pressure, cotton variety, other sources of income etc. raises the suspicion that Karthage and Qaim's study is another example of pro-GM propaganda dressed up as science. This wouldn't be the first time such pseudo-science has appeared in a peer-reviewed journal.

GM Watch has pointed out that one of the paper's authors has been 'at it' before:
“Qaim has been an author in other controversial papers related to Bt cotton in India. For instance, it is well-known that data supplied by the crop developer from the field trials was sought to be passed off as the author's findings in 2002. Incidentally, in a 2005 paper, he was one of the authors who sought to explain away “paradoxes” in Bt cotton by arguing that it is the host germplasm that matters while everything's fine with the Bt technology.”
 The moral of the tale is, if reports about the success of a GM crop seem too good to be true, they are probably too good to be true.

  • Jonas Kathage and Matin Qaim, 2012, Economic impacts and impact dynamics of Bt (Bacillus thuringiensis) cotton in India, PNAS
  • Critique of studies hyping Bt cotton, GM Watch, 10.07.12
  • Rahul Wadke, Mahco may lose license to sell Bt seeds in Maharashtra, The Hindu, 12.07.12
  • Vidarbha Cotton Farmers Welcome Maharshtra Government decision to Ban Mahyco-Monsanto Biotech (MMB) BtCotton Seed,, 12.07.12
  • Netha Saigal, Bt cotton kills pests or farmers? Tehelka, 5.07.12#
  • Genetically Modified truths and an Outstanding Quest,, 20.08.12

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