Moving towards a rat-free world

Researchers reveal GM plan to wipe out the rodents

IT is a far more sophisticated solution than setting a trap or laying out poison-laced cheese.

Scientists say pest problem may soon be solved by releasing genetically engineered rats.

The University of Edinburgh says within two years rats could be made infertile by tweaking their genes, or made to have only male offspring.

These laboratory rodents, released into the wild to pass on their mutant genes, could cut rat populations in cities like London, where the urban myth goes that residents are never more than six feet away from a rat.

GM mosquitoes are already being created in Australia to protect people from the malaria carried by the deadly insects.

However the British scientists will be the first to try the technique out on mammals.

Gus McFarlane, co-author of a study on the solution, said: ‘There are obvious benefits of this gene drive strategy compared to current control measures that are really quite brutal – shooting, poisoning, trapping, kind of ‘bash over the head’ techniques.

‘It is more humane to cause a population decline with minimal animal suffering.

It is species-specific, as you are only targeting the target species you plan to, and also potentially more cost-effective.’

There are believed to be tens of thousands of rats in Britain, which have caused devastation in certain areas.

Scientists say the creatures could be stopped from breeding using CRISPR/Cas 9 – a technique which works like ‘molecular scissors’ to snip away DNA.

This technique works to disrupt a fertility gene in rats, to make females infertile. It can also skew the sex ratio which makes some baby rats male with an XY pair of chromosomes and some female with an XX pair.

By ‘shredding’ the X chromosome, scientists have made almost 95 per cent of mosquito offspring male - cutting birth rates massively because there are not enough females to breed. Edinburgh University’s Roslin Institute hopes to start trialling both techniques in a ‘contained and controlled’ rodent lab within two years.

Professor Bruce Whitelaw, principal investigator at Roslin Institute, where Dolly the sheep was famously cloned, said: ‘We have the makings of a technology that could reduce or eliminate a pest population in a humane and species-specific manner.

‘We need more research to better understand the risks, and whether these can be mitigated, but we believe the potential benefits merit further investigation.’

The genetically modified rats would pass on their infertility or likelihood to have male offspring to the next generation, scientists believe. It means a mutant gene could spread throughout an entire population within as few as 10 generations.

Pest control costs the UK economy an estimated £ 1.2 billion each year, with the British Pest Control Association reporting more than 186,000 call-outs relating to rats in a single year.