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OSB archive

Sterile or virile? How about both...

Pete Wilton

Is it better to sterilise males with a dose of radiation or by inserting a gene?

That's part of the thrust of an article by Clive Cookson in the FT on the work of Oxford spinout Oxitec.

Of course what we are talking about are males of insect species that bring untold suffering to human populations around the globe.

The basic idea is simple: release large numbers of sterile males into infected areas so that they mate with all the available females who then produce no offspring.

But there's a problem: up until now the sterilisation has been achieved using radiation, but this doesn't work with the mosquitoes carrying dengue fever: unfortunately a dose high enough to render males sterile will kill or incapacitate them.

Now, in collaboration with Oxford scientists, Oxitec have found a more targeted way to sterilise male mosquitoes by inserting a 'dominant lethal' gene. 'The males produce viable sperm which will fertilise the egg, but the embryo [larva] dies in development,' said Oxitec's Luke Alphey, who left the University this year to work for the company full time.

So you get sterility AND virility.

It's an elegant solution which uses the antibiotic tetracycline to suppress the gene so that 'sterile' mosquitoes can be bred (remove tetracycline and any larva die). 

Of course many will baulk at the idea of unleashing a 'genetically modified flying army' into the wild. But, according to Luke, the gene can't 'escape' because the sterile males can't pass it on. 

The reaction of those in dengue-affected areas will be interesting. So far alternative approaches including insecticide fogging and improved sanitation haven't had much impact on the 100 million or so people afflicted by dengue every year.

If you lived under the threat of this disease would you be squeamish about releasing GM insects to destroy an insect species that is, in any case, alien to the region?