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GM boosts bug populations

Sun, 16th May 2010

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Scientists have found that cultivating pest-resistant GM crop strains can paradoxically create a whole new breed of bugs!

Writing in Science, Beijing-based researcher Yanhui Lu and colleagues show that after ten years of growing GM cotton in northern China, a previously low-level pest, called the mirid bug, has now risen to prominence and become a serious problem.

Lygus pratensisThe cotton plants in question have been engineered to produce a toxin made by the bacterium Bacillus thuringiensis (Bt), which kills off susceptible pests that try to devour the cotton plants, including one notorious nuisance, the cotton bollworm, Helicoverpa armigera.

In China, the modified plants account for over 95% of the cotton grown.  This has, in turn, translated into a dramatic reduction in pesticide use, but therein lies a problem.

Prior to the introduction of GM Bt cotton, farmers sprayed regularly against bollworm, which also had the effect of killing off other low-level pests like mirid bugs.  But with the introduction of the GM cotton strain, and the cessation of spraying, the researchers found that the mirid bugs, which are actually not affected by the Bt toxin, have increased their numbers dramatically.

But more significantly, they don't remain confined to the cotton field.  Being fairly unfussy eaters, they also spread to and infest other local crop species nearby.

This shows, say the scientists, that "area-wide cultivation of transgenic crops may bring various (direct and indirect) effects on ecological status of different organisms, which should be assessed or anticipated in a comprehensive fashion."



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I believe that the greatest problem with GM plants is that there has been insufficient time to fully assess their effects and consequences.  Our relationship with food crops has developed over many thousands of years yet GM crops are being claimed to be safe and have to have known effects and consequences after considerably less than half a century of testing.

While selective breeding has always occurred, both with plants and with animals, it can only produce hybrids that might otherwise naturally happen.  With GM modification though, new 'impossible' organisms are being created for which there are no precedents to guide us in predicting their characteristics.  While we may have a good idea of the characteristics of interbreeding, let's say, two different varieties of cow, how could we predict how a cross between a cow and a mouse to behave?

And let's not forget that even when 'natural' hybrids are created things can still go badly 'wrong', as in the case of the Africanised Honey Bee.

In view of this, I think it is simply impossible to predict, with any real degree of certainty, the long term consequences of GM plants. LeeE, Tue, 18th May 2010

it is these possibilities that cause many people to invoke the precautionary principle in dealing with GMOs.

We do not (fully) understand the longterm consequences of widespread use and possible cross-fertilization of GMOs and pp would state that in this case risks cannot be simply factored into a cost benefit analysis.  "When an activity raises threats of harm to human health or the environment, precautionary measures should be taken even if some cause and effect relationships are not fully established scientifically"  When playing for ultimate stakes I believe it pays to be very risk averse.

imatfaal, Wed, 19th May 2010

The precautionary principle bans progress. Why try penicillin when we don't know the long term consequences?
As soon as someone tries to cross a cow and a mouse this "how could we predict how a cross between a cow and a mouse to behave?" will stop being a straw-man.

The Africanised bees aren't strictly Natural. They were a deliberate cross breed brought about by people who saw some beneficial aspects to the African bees and brosssbred them with European honey bees.
They got a whole lot of other traits they didn't want.
The point to GM is that you find the gene for the particular trait you want from the African bee (IIRC it was better yields in the hot tropical areas) then add just that tiny bit of the genome to the European bee.

Surely that's a safer way to do it than the "hit and hope" strategy that gave us this problem. Bored chemist, Wed, 19th May 2010

BC - the precautionary principle does not ban progress - it seeks to force policy-makers to understand risk before an irreversible decision is taken.  the penicillin argument is almost as much of a straw man as the mouse/cow hybrid. the pp does not look to eliminate risk, it seeks to limit those situations in which unquantified and unquantifiable risks are taken. 

knee jerk reactions against new technology are as damaging as not performing risk assessment and I do not count myself as a luddite; but I still hold that many projects whose cost-benefit analysis are very positive have boundless and under-researched risks.  Actually the principle is in full operative effect already, in its strongest form, in the regulation of pharmaceuticals.  Many-layered, highly regulated testing protocols must be followed (at the time and expense of the developer) to reach a level of certainty that any innovation is not harmful.  There is no “benefit of the doubt”, even for potentially revolutionary treatments.  If any research points to a danger in an existing drug, immediate action is taken.

many characterisations of the implementation of the precautionary principal portray scientific advances being restricted by opponents of technological progress - but in reality the actual governmental and supra-governmental structure that practice the principle are heavily reliant on scientific advice on both sides.  It is when this scientific advice is contradictory and the potential negative outcomes are catastrophic that the principle urges caution and a reversal of the burden of proof.  Matthew imatfaal, Wed, 19th May 2010

Since it is impossible to foresee all possible risks, the precautionary principle (as used by GM opponents) bans progress.

They talk about "proving that it's safe".

Re. "There is no “benefit of the doubt”, even for potentially revolutionary treatments.  If any research points to a danger in an existing drug, immediate action is taken."
Yes, but that action is not "ban it!".
Every drug has side effects, plenty of them are serious.
The sensible action is to look at the risk and ask if it is outweighed by the benefit.
The GM opponents are only going to be satisfied by an infinitely long series of "safety trials" which are, in reality, a stalling measure. Their opposition has nothing to do with risk, but a perception that GM is "unnatural so it's morally wrong" Bored chemist, Thu, 20th May 2010

BC - the risks of prescription a drug with side-effects can and must be quantified - once this is done a cost-benefit analysis is carried out and advice given accordingly.  the idea behind the precautionary principle is that in some cases the present position of scientific knowledge allows no quantification of risks.  As you say yourself "The sensible action is to look at the risk and ask if it is outweighed by the benefit" but in many cases the risks CANNOT be weighed against the benefit. 

in any real-world application of the precautionary principle, and there are many, there is no talk of absolute proof of safety - the principle comes into effect when the balance of scientific opinion (not public nor n.g.o. nor pressure group opinion) is divided on the hazards that exist and the risk of these hazards occurring.  the problem (that should and must) be solved with tests of GMO crops is that the possibility of cross-contamination with non-GMO crops is high.  as this is a hazard that opponents of GMO crops wish to avoid it has become a very 'useful' stumbling block to further testing.  there is no excuse for shelving potential very beneficial research because the testing is not easy - and no advocate of the principle would wish to limit testing or avoid finding an 'answer'.

it is unfortunate that the action of an eminently sensible political device has become the battlefield upon which free-market values are pitted against ecological concerns.  the argument has been drawn to the extremes and become ideological - but I firmly believe that the precautionary principle is a midpath that should be trodden; it is not the block to progress that free-market libertarians claim it to be and radical greens want it to be.  Matthew

imatfaal, Thu, 20th May 2010

The people who talk about the precautionary principle WRT GMO are not in the real world.
They don't talk about cost/ benefit analysis. They only talk about the potential bogeyman of some undefined "harm". Bored chemist, Thu, 20th May 2010

At this point in the development of GMOs, the people who advocate the precautionary principle are just saying that they don't want to be lab rats.

In the long term there is no doubt that the future is in genetic modification, and not just with plants and animals but with people too, but asserting that we already know everything we need to know, at this stage of development, right now, is simply foolish.

Oh, and claiming that anyone who opposes the immediate take-up of GMOs... as bad an exaggeration as claiming that they are 100% safe: it is no more a valid scientific argument for GMOs than those arguments against GMOs, which you are trying to refute. LeeE, Thu, 20th May 2010

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