Silencing genes is all the rage

February 2014
image of a field of corn
Field of corn. By Hugho226 (Own work) [CC0], via Wikimedia Commons
Monsanto's latest venture into the brave now world of GM should give you pause for thought.  Or, several pauses. 

Having finally admitted that its 'Bt' insecticidal crops, designed to kill 'western corn rootworm' have reached the end of their shelf-life due to evolving resistance, Monsanto has found another GM way to kill this major pest. 

The Company has applied for regulatory approval for a new GM corn which produces a gene-altering agent, referred to generically as 'iRNA'.  Insecticidal iRNA is designed to kill insects by shutting down one of their vital genes. 

Scientists have already voiced concerns about this technology because it is based on the assumption that the target genetic sequence to be silenced is unique to the pest , and that reactions to iRNA in food aren't possible.  Neither of these assumptions is scientifically valid [1,2].  This makes putting copious artificial iRNA into the field and food chain the most health-threatening GM adventure yet. 

The novel, novel corn is expected to be on the market by the end of the decade  and will be sold as “SmartStax Pro”.  (COMMENT  Presumably this means it will have a whole set of genes for Bt proteins and for resistance to various herbicides besides the iRNA.  Nice cocktail for the pot.) 

Monsanto is also finally admitting that the Roundup resistant superweeds it has created by pushing farmers into ever-increasing applications of a single herbicide on their GM crops has reached the end of its tether.  The Company is busy developing a novel spray designed to kill superweeds.  Its tactic is to deluge intransigent weeds with an iRNA-containing formula which silences the weeds' newly evolved Roundup-resistance genes.  There is, of course, the added benefit that farmers can continue use Roundup on their crops, and Monsanto can continue to reap the profits from its best-selling herbicide. 

Put another way, Monsanto's novel spray contains iRNA designed to penetrate into living cells and interfere with the function of genomes.   

Is it likely to work?  Possibly, but in a limited way, because weeds have evolved quite a variety of sneaky genetic ways to resist Roundup [3], and such a tactic won't work for long, because weeds are just too clever at changing their genes.   

Is it likely to be safe for the environment  or for us?  The likelihood of unpredictable cross-reactions with non target genes suggests no.   

Will it make a big profit for Monsanto?  Yes, pesticides are a huge money spinner even if they're destined inevitably to fall apart. 

A more unusual avenue for Monsanto's GM skills is the current development of iRNA to kill the mites which are destroying our honey bees.  This may be a useful diversion from the suspicion that its Bt crops and agrichemicals are contributing to bee colony collapse [4].  However, bee keepers aren't sold on the idea

“To attempt to use this technology at this current stage of understanding would be more naïve than our use of DDT in the 1950s” (US National Honey Bee Advisory Board). 


The National Honey Bee Advisory Board has said it all. 

Perhaps you could repeat this point to the EU and UK regulators, just in case they're feeling a bit naïve about the risks of iRNA. 


[1]  RNA MODIFIED FOOD - July 2013

[3]  WEEDS HAVE TRICKS UP THEIR SLEEVES - (Online document link) GMFS ARCHIVE - February 2010

[4]  HONEYBEES AND TOXIC GM SEEDS - News, February 2012



Andrew Pollack, Genetic Weapon Against Insects Raises Hope and Fear in Farming, New York Times, 27.01.14

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