Superweeds: are GM trials a danger to society?

[Mark]

Superweeds: are GM trials a danger to society?

George Weller examines some of the perceived dangers of GM trials and why, he believes, they do not pose a serious threat after all.

Genetic modification (GM) was once again in the news this year as protesters attempted to halt a GM wheat trial at Rothamsted Research. GM technology can provide crop plants with enormous advantages. However, as protesters argued at Rothamsted if these advantages are accidentally transferred to wild plants the consequences could be serious. Fortunately as many commenters pointed out at the time, this is extremely unlikely to happen due to the way that wheat is pollinated.

The reason this is so unlikely is because modern agricultural wheat usually self-pollinates. The pollen grains produced in a flower fertilise eggs inside that same flower, often before the flower has even opened. The small amount of pollen that does eventually leave the flower is carried by the wind and its dispersal is limited by its relatively high weight. In a recent experiment, GM wheat was planted two and a half metres away from non-GM wheat and only 0.03% of the seeds produced by the non-GM plants were the result of cross-pollination from the GM plants. Besides, even if some GM pollen did escape and land on a wild relative of wheat, successful pollination is unlikely to occur, since agricultural wheat has a very different genetic structure to even its closest wild relatives.

Lukasz Jernas Unfortunately, extremely unlikely is not the same as impossible. It would only take a single grain of GM pollen to get caught by a strong wind and, by pure fluke, travel far enough to reach wild relatives and it just might, against the odds, fertilise a non-GM plant, resulting in uncontrolled spread of the new gene.

This potential ‘GM contamination’ could have damaging consequences. Whatever favourable trait had been introduced to the original GM plant (for example, the ability to repel hungry insects or survive herbicide treatment) would now be found in the ‘contaminated’ wild plant. If this new ability conferred a great enough advantage, then the wild plant could become a ‘superweed’. It would grow and reproduce so successfully that it might prevent the growth of other plants, resulting in a loss of biodiversity. Such weeds could also cause problems for agriculture if they spread into farmers’ fields. Fortunately, new approaches in genetic engineering should soon make these events impossible.

One of these new approaches is to engineer the GM plants to be sterile. The plants are manipulated in such a way that any seeds they produce are unable to germinate and produce new plants. This means that even if GM pollen does manage to escape its field and find a wild plant that it is able to fertilise, the offspring produced will be destined to remain as seeds and will never grow up into potentially harmful weeds. There is, however, a major problem with this strategy. It prevents farmers from being able to save their seed and replant it the following year. It has been heavily criticised by the anti-GM lobby, who dubbed it ‘terminator technology’, because it could cause farmers to become dependent on seed companies to sell them new seeds each year.

Michael Jastremski  An alternative strategy that avoids this problem is to engineer the plants in such a way that the GM trait can only be inherited from the mother. The pollen (which is male) is able to leave the plant on which it is produced, whereas the egg cells (female) stay put and wait for incoming pollen to fertilise them, leading to the formation of a seed. It is possible to create a GM plant in such a way that the new gene is found only in the eggs and not the pollen. This means that there is no chance of the new gene escaping the field, but the eggs can still be fertilised to produce GM seeds that can be planted the following year. This has already been achieved for several crops plants by inserting the desired new gene into special locations within the cell.

Even if strategies such as this serve simply to cut the risk of cross-pollination further and do not eliminate it completely, it is still important to continue with tests such as the one at Rothampton. Only with these tests can we continue to reap the benefits of genetic engineering whilst ensuring that we continue to develop new ways to limit any harmful side-effects.

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[Psalm 51:17]

http://www.dailymail.co.uk/news/article-2211737/How-GM-crops-increased-use-danger-pesticides-created-superweeds-toxin-resistant-insects.html#ixzz28FnXEPSY

How GM crops have increased the use of danger pesticides and created superweeds and toxin-resistant insects

10/2/12

Planting GM crops has led to an increase rather than a decrease in the use of pesticides in the last 16 years, according to US scientists.

The researchers said that the plants have caused superweeds and toxin-resistant insects to emerge, meaning farmers have not only had to use more pesticides on their crops overall, but are also using older and more dangerous chemicals.

The findings dramatically undermine the case for adopting the crops, which were sold to farmers and shoppers on the basis that they would reduce the need to be treated with powerful chemicals.

The team at Washington State University found the weight of chemicals used on US farms has increased by 183million kilos since GM crops were introduced in 1996.
 
Of that total, herbicide use increased over the 16-year period by 239million kilos while insecticide use decreased by 56million kilos.

Most GM crops produced to date – such as corn, soya and cotton – have been modified in the laboratory to make them immune to certain weedkillers, such as Monsanto’s RoundUp.
 
It means the GM plants can  thrive while the surrounding weeds are wiped out.

However, the reality is that a number of weeds have developed an immunity to the chemical and are now able to swamp farmers’ fields.
 
The biggest threats are giant ragweed and pigweed, which grows at a rate of more than one inch a day and reaches a height of three metres.

The so-called perfect superweed is extremely hardy, produces 10,000 seeds at a time and will smother food crops in the same field.

The overall effect is that desperate farmers are now using a cocktail of many different chemicals to try and tame the weeds.
 
A number of GM plants, including some types of corn, have been modified to include a toxin called Bt that kills predator insects that feed on them.
 
But again, these insects are developing an immunity to the toxin included in the plants, which means farmers have to resort to chemical sprays.
 
Study leader Professor Charles Benbrook, of the university’s Center for Sustaining Agriculture and Natural Resources, said: ‘Resistant weeds have become a major problem for many farmers reliant on GM crops and are now driving up the volume of herbicide needed each year by about 25 per cent.

‘Things are getting worse, fast. In order to deal with rapidly spreading resistant weeds, farmers are being forced to expand use of older, higher-risk herbicides.
 
‘To stop corn and cotton insects from developing resistance to Bt, farmers planting Bt crops are being asked to spray the insecticides that Bt corn and cotton were designed to displace.’
 
Monsanto said they had no immediate comment on the findings.

A spokesman said: ‘We’re looking at this. Our experts haven’t been able to access the supporting data as yet.’

Professor Benbrook’s paper is published in the peer-reviewed journal Environmental Sciences Europe and comes two weeks after a feeding trial in rats raised concerns that consuming GM corn might trigger a rise in breast cancer and organ damage.
 
Recently, scientists who have published studies critical of GM crops and food have suffered a wave of well-orchestrated attacks designed to undermine their work by supporters of the technology.