sábado, noviembre 27, 2010

Bt Cotton Falls Short of Expectations in Kartanaka

Dear Friends and colleagues,
RE: Bt Cotton Falls Short of Expectations in Kartanaka, India
A new report shows that Bt cotton in India has not lived up to the many claims and promises. The report, which looks at the experience of Kartanaka between 2002-2009, demonstrated an increased use specifically of insecticide on cotton while findings indicate the emergence of pests like mirid bugs in cotton which is causing heavy losses in certain districts. (Item 1)
Further, cost of production per quintal of cotton in the state of Kartanaka continues to show an erratic trend, as they were before the introduction of Bt cotton. In fact, costs were even lower before Bt cotton entered the scene, according to official data.
The problem of pests among Bt cotton is also experienced among cotton growers in China, where mirid bugs, once minor pests, have now become the main pests in Northern China. There is now concern that pesticides use will increase dramatically as growers increase their use to fight the pest problem. (Item 2)
The conclusions of the report "An overview of Bt Cotton experience in Karnataka: 2002 to 2009" is reproduced below. The full document is available for download at: http://www.biosafety-info.net/article.php?aid=740
With best wishes,
Third World Network
131 Jalan Macalister,
10400 Penang,
Item 1
1. Claims made in support of Bt Cotton either in terms of pesticide usage or yields or economics do not hold as the data presented in this brief review shows.
2. Insecticide usage in Karnataka in cotton crop has actually increased as per the official NALMOT data presented in this review. This belies the rationale for bringing in Bt Cotton.
3. Secondary data shows that Bt Cotton was working well only in irrigated conditions whereas a majority of cotton cultivation in Karnataka is in unirrigated conditions.
4. Cost of cultivation per quintal of cotton in Karnataka show fluctuating trends as was the case even before the advent of Bt Cotton. In fact, lower costs were present before Bt Cotton entered the scene, as official data from the recent past shows.
5. Other data on various Bt Cotton hybrids right now in the market from CICR shows that non-Bt Cotton's average lint yield is higher than the average of the Bt Cotton hybrids studied.
6. In the top five cotton growing districts of Karnataka, the picture with yields is that of dramatic fluctuations and variability across years and districts.
We conclude that Bt Cotton has not delivered on its claims and promises and it is important that the Government of Karnataka takes up an official review to look at the situation, given that field visits are pointing out to lack of supply of any other seeds, leaving very little choices for the farmers of the state.
Item 2
GM crop use makes minor pests major problem
Pesticide use rising as Chinese farmers fight insects thriving on transgenic crop.
Jane Qiu
Growing cotton that has been genetically modified to poison its main pest can lead to a boom in the numbers of other insects, a ten-year study in northern China has found.
In 1997, the Chinese government approved the commercial cultivation of cotton plants genetically modified to produce a toxin from the bacteria Bacillus thuringiensis (Bt) that is deadly to the bollworm Helicoverpa armigera. Outbreaks of larvae of the cotton bollworm moth in the early 1990s had hit crop yields and profits, and the pesticides used to control the bollworm damaged the environment and caused thousands of deaths from poisoning each year.
More than 4 million hectares of Bt cotton are now grown in China. Since the crop was approved, a team led by Kongming Wu, an entomologist at the Chinese Academy of Agricultural Sciences in Beijing, has monitored pest populations at 38 locations in northern China, covering 3 million hectares of cotton and 26 million hectares of various other crops.
Numbers of mirid bugs (insects of the Miridae family), previously only minor pests in northern China, have increased 12-fold since 1997, they found. "Mirids are now a main pest in the region," says Wu. "Their rise in abundance is associated with the scale of Bt cotton cultivation."
Wu and his colleagues suspect that mirid populations increased because less broad-spectrum pesticide was used following the introduction of Bt cotton. "Mirids are not susceptible to the Bt toxin, so they started to thrive when farmers used less pesticide," says Wu. The study is published in this week's issue of Science1.
"Mirids can reduce cotton yields just as much as bollworms, up to 50% when not controlled," Wu adds. The insects are also emerging as a threat to crops such as green beans, cereals, vegetables and various fruits.
Rise of the mirids
The rise of mirids has driven Chinese farmers back to pesticides - they are currently using about two-thirds as much as they did before Bt cotton was introduced. As mirids develop resistance to the pesticides, Wu expects that farmers will soon spray as much as they ever did.
Two years ago, a study led by David Just, an economist at Cornell University at Ithaca, New York, concluded that the economic benefits of Bt cotton in China have eroded2. The team attributed this to increased pesticide use to deal with secondary pests.
The conclusion was controversial, with critics of the study focusing on the relatively small sample size and use of economic modelling. Wu's findings back up the earlier study, says David Andow, an entomologist at the University of Minnesota in St Paul.
"The finding reminds us yet again that genetic modified crops are not a magic bullet for pest control," says Andow. "They have to be part of an integrated pest-management system to retain long-term benefits."
From the ashes
Whenever a primary pest is targeted, other species are likely to rise in its place. For example, the boll weevil was once the main worldwide threat to cotton. As farmers sprayed pesticides against the weevils, bollworms developed resistance and rose to become the primary pest. Similarly, stink bugs have replaced bollworms as the primary pest in southeastern United States since Bt cotton was introduced.
Along with genetically modified crops, says Andow, farmers need effective systems for responding to changes in pest abundance. This needs to be based on research into the timing, dosage and frequency of pesticide use needed to tackle new pests. "When farmers decide how to control pests, they tend to overuse pesticides," he says.
Wu and his colleagues are seeking the most effective way to use pesticide, and trying to reduce mirid damage to cotton by growing crops the pests prefer nearby. Meanwhile, Chinese researchers are trying to develop cotton plants that kill both bollworms and mirids.
Wu stresses, however, that pest control must keep sight of the whole ecosystem. "The impact of genetically modified crops must be assessed on the landscape level, taking into account the ecological input of different organisms," he says. "This is the only way to ensure the sustainability of their application."
1. Lu, Y. et al. Science advance online publication doi:10.1126/science.1187881 (2010).
2. Wang, S., Just, D. & Pinstrup-Anderson, P. Int. J. Biotechnol. 10, 113-120 (2008). | Article | OpenURL

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