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Matt Ridley is the author of provocative books on evolution, genetics and society. His books have sold over a million copies, been translated into thirty languages, and have won several awards.

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Collateral beneficence

GM crops benefit non-GM crops nearby

Do you remember how, back in the days when genetically modified crops were as vilifed as climate sceptics were until recently, one of the arguments deployed against them was that they would `contaminate' neighbouring farms with their genetically modified pollen? This was one justification for a total ban, as there still is in Britain, rather than a policy of live and let live.

Now comes evidence of a different kind of collateral contamination by GM crops. Turns out GM maize contaminates neighbouring farms with extra profits. The fact that farmers are growing insect-resistant GM crops raises yields for those who are growing conventional maize, because it reduces the number of pests that are about.

 

By comparing actual insect damage against estimates of what damage would have occurred - derived from historical data and other measures of borer abundance - the researchers calculated that over the 14 years of their study, use of Bt varieties improved farmers' profits by about $3.2bn in Illinois, Minnesota and Wisconsin.

But most of this benefit - $2.4bn - was accrued in non-Bt fields.

This `area-wide suppression' effect is presumably true of chemical pesticides, too. An organic farmer with weedy, pest-infested fields is contaminating his neighbours' fields with weeds and pests, or to put it another way his neighbours are contaminating him with crop protection. Who's the free rider?

But the brilliant thing about Bt crops, of course, is that because the toxin is made inside the plant, you can only encounter it if you eat the plant, so the general insect fauna is unaffected. It can therefore thrive, unsprayed.

Higher profits for farmers means lower costs for consumers (think about it: competition can drive prices lower and effectively pass on the extra profits as savings). So GM crops are leading to higher yields which means ploughing less land, cheaper food and more insect life, which means more bird life.

Will somebody please remind me why my government still cravenly accepts a total ban on the growing of these crops in my country at the behest of so-called `green' groups? It is a disgrace.

I now walk out of restaurants if they say they do not serve GM food and I tell them why.