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[SANET-MG] bollgard cotton compromised in India
Nature Biotechnology
Published online: 1 November 2005; | doi:10.1038/nbt1105-1326
Monsanto's Bollgard potentially compromised in India
A fresh controversy has erupted over Bacillus thuringiensis (Bt) cotton
after the publication of a study by a government institute in India
showing that Bt cotton planted in India is not as efficient in killing
bollworms there as it is in the US or China.
K.S. Jayaraman
Controversy has erupted in India over the quality of imported Bt cotton
seeds, which are deemed inappropriate for India's long ripening season.
Rachel Weill/PictureArts
A fresh controversy has erupted over Bacillus thuringiensis (Bt) cotton
after the publication of a study by a government institute in India
showing that Bt cotton planted in India is not as efficient in killing
bollworms (Helicoverpa armigera) there as it is in the US or China.
That's because it is not designed for India's longer ripening season.
The findings have subsequently been exploited by a nongovernmental
organization (NGO), which has alleged that US seed company Monsanto of
St Louis, Missouri, exported to India a technology primarily suited for
Western markets and not for Indian farmers. Their charge—not entirely
denied by Monsanto—raises concerns that bollworm resistance to Bt cotton
could emerge in the country.
The finding by the Central Institute of Cotton Research (CICR) in Nagpur
published in Current Science ( 89, 291–298 (2005)) last July has
embarrassed the Genetic Engineering Approval Committee (GEAC), India's
apex regulatory body. The study that triggered the controversy, led by
Keshav Kranthi, showed that Bt hybrids commercially grown in India
express less than the critical levels of the Cry1Ac Bt toxin required
for full protection against bollworms late in the season. The toxin
expression varied from hybrid to hybrid and was higher in leaves than in
boll rind, bud and flower. This type of protection works well against
Heliothis virescens, or tobacco budworm, a major pest in the US that
feeds on leaves, but doesn't work against H. armigera, the major pest in
India, which feeds mostly on bolls.
Tony Shelton, entomology professor at Cornell University in New York, is
not surprised at Kranthi's conclusions. "It is already well documented
that Cry1Ac cotton in general is not a consistent high dose–expressing
plant for Helicoverpa," he points out. He adds, "the lack of a high dose
[of the toxin] (in late season) will increase the likelihood of
resistance development."
To remedy these potential problems, Kranthi suggests in his publication
"India should focus on developing transgenic cotton varieties with
tissue-specific promoters to enhance the expression of toxin genes in
fruiting parts." He also writes that seed companies should evaluate
their hybrids critically for the highest levels of expression in
fruiting parts and also for a relatively effective level of toxin
expression late in the season.
After the publication of this study, Gene Campaign, a New Delhi-based
NGO, has demanded an inquiry to examine whether both Monsanto and GEAC
have misled Indian farmers—the former by exporting the wrong technology
and the latter for approving 13 new Bt hybrids this year ignoring the
findings of CICR. The GEAC held two meetings on August 10 and September
16 to discuss the implications of the study but has withheld comments.
Monsanto's Graham Head, who is responsible for global coordination of
insect resistance management, says this drop in protection is linked to
a long ripening season for cotton in India—an issue that also crops up
in Australia. It apparently causes no problem for farmers in the US
where the ripening season is shorter (Nat. Biotechnol. 21, 958—959,
2003). "But it is an issue for Indian farmers who prefer to grow
medium-to-long duration hybrids for their big boll size and superior
fiber properties," argues Suman Sahai, president of Gene Campaign.
Monsanto claims they have ongoing research efforts to improve each new
variety of Bt and take into account late-season problems.
Kranthi also suggests that part of the problem has to do with the
cultivation of hybrids in India, which are used instead of true
varieties grown in the US, Australia and China. For instance, 25% of the
seeds from hybrid bolls grown in India do not express the Cry1Ac,
whereas all seeds in true varieties contain the toxin. "A global
analysis on the comparative performance indicates that Bt-cotton
varieties appear to be more effective in controlling the Helicoverpa
species compared to the hybrids being grown in India," Kranthi writes.
Gene Campaign's Sahai argues that Monsanto is promoting the use of
hybrids in India to force farmers to buy fresh seeds every year even
though it is aware that true varieties (whose seeds can be saved for
subsequent crops) do better. But Ranjana Smetacek, a Monsanto
spokesperson in New Delhi says the choice of hybrids was purely
circumstantial. "When we first considered taking our cotton traits to
India, we found that most of the cotton seed companies that were capable
of working with us to bring our traits to Indian farmers sold hybrids."
She said that as a consequence, Monsanto decided to initially work with
Mahyco, a major provider of hybrid seed in Jalna, and subsequently
licensed its gene to a number of other hybrid seed companies. "Since
that time, growers have adopted hybrid seed even more, so we believe
that we made the correct decision."
But not everyone—including Kranthi—agrees. In a lengthy article
published on September 2 in the newspaper Hindu, he writes, "Indian
researchers including our own group at CICR must intensify the efforts
to develop Bt straight varieties for the use of Indian farmers."
Ebrahimali Siddiq, former deputy chief of the Indian Council of
Agricultural Research, doubts if companies will switch to true varieties
because they have already spent a lot on hybrids. "One way to use
hybrids and still avoid the problems found by Kranthi is to use parental
lines each having a different Bt gene so that both genes are present in
the hybrid," he comments. "I think there is plenty of scope for research
here." According to Shelton, in Australia, dual Bt gene cotton has
already replaced single Bt gene cotton.
As a result of the difference of efficacy of hybrids, Kranthi concludes,
"Bt cotton hybrids in India may therefore require more supplemental
insecticide sprays than [are] being used on Bt-cotton varieties
elsewhere in the world." Monsanto's Smetacek says the company has always
warned "Bollgard cotton is not a panacea." Farmers are directed to scout
their Bollgard fields for insects and supplement the protection by
treating with an insecticide whose amount "varies from country to
country," she remarks.
Higher survival of cotton bollworm on Bt cotton will not necessarily
speed its resistance to Bt cotton, particularly if survival of
susceptible pests increases as reported by Kranthi.
Bruce Tabashnik
an entomologist at University of Arizona
Entomologist Bruce Tabashnik of Arizona University cautions against such
practice. Citing a recent Australian study, he says that decline in
Cry1Ac concentration in Bt cotton late in the season causes nonrecessive
inheritance of resistance in H. armigera. "Higher survival of cotton
bollworm on Bt cotton will not necessarily speed its resistance to Bt
cotton, particularly if survival of susceptible pests increases, as
reported by Kranthi," says Tabashnik. But he fears "incomplete control
of cotton bollworm by Bt cotton will not reduce insecticide use enough
to avoid resistance to the sprayed insecticides."
Hyderabad
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