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[SANET-MG] insect resistance management in gm crops
The paper below proclaims that GM crops bearing insecticidal proteins
have been used for a number of years without giving rise to resistant
insects. The report deals with the refuge strategy and the use of high
toxin dosage along with pyramiding toxin genes as factors preventing
insect resistance from arising.However, the main reason that insect
resistance has not been detected was not mentioned in the article. The
main reason that insect resistance has not appeared is that the US EPA
allows the gm crop and refuge to be sprayed with chemical
insecticides.The refuge strategy of insect resistance provides crop
areas in which the target insect pest may thrive and breed with
resistant insects from the gm crop (insect genes for resistance are
usually recessive). Spraying chemical insecticides allows taking damage
free crops from the refuge but it also rubs out any resistant insects.
Another unmentioned factor that effects resistance is the use of
synthetic toxin genes in the various commercial gm crops that vary in
both toxin production and the actual sequence of the toxins. However,
that factor is far less imposing than the combination of GM crop toxin
and chemical insecticides.
In Canada chemical insecticides have not been allowed in the refuge of
Bt crops , but there does not appear to have been any effort to screen
for resistance in that country.
Why did the report ignore the use of chemical pesticides in combination
with refuge in gm crops? I think it may be related to the rise of public
relations in science publications. Traditionally , science reporting
demanded full and truthful reporting but with the paranoia of genetic
engineering those who report things not favoring public relations of gm
crops are punished severally.
Nature Biotechnology 23, 57 - 62 (2005)
Published online: 06 January 2005; | doi:10.1038/nbt1056
Insect resistance management in GM crops: past, present and future
Sarah L Bates, Jian-Zhou Zhao, Richard T Roush & Anthony M Shelton
Transgenic plants expressing insecticidal proteins from the bacterium
Bacillus thuringiensis (Bt) were first commercialized in 1996 amid
concern from some scientists, regulators and environmentalists that the
widespread use of Bt crops would inevitably lead to resistance and the
loss of a 'public good,' specifically, the susceptibility of insect
pests to Bt proteins. Eight years later, Bt corn and cotton have been
grown on a cumulative area >80 million ha worldwide. Despite dire
predictions to the contrary, resistance to a Bt crop has yet to be
documented, suggesting that resistance management strategies have been
effective thus far. However, current strategies to delay resistance
remain far from ideal. Eight years without resistance provides a timely
opportunity for researchers, regulators and industry to reassess the
risk of resistance and the most effective strategies to preserve Bt and
other novel insect-resistant crops in development.
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