Mutant rats may hold the key to pest control

Scientists plan to spread infertility and stop growing numbers of pests

Genetically mutated rats could be released to help tackle the growing problem with rodents, Edinburgh University has said. Scientists have launched a project to find out if genetically editing animals to make offspring produce only males may provide more humane pest control.

GENETICALLY mutated rats could be released to help tackle the growing problem with rodents, Edinburgh University has said.

Scientists have launched a project to find out if genetically editing animals could provide a more humane method of pest control.

Figures released last week show that London councils receive 100 complaints about rats and mice each day, with some local authorities reporting a 10 per cent increase in the number of rodents since last year.

Most pest controllers use poison, but rats are fast becoming resistant to even the strongest toxins, and poison risks harming other animals.

Now experts at Edinburgh University believe that a process called “gene drive’”could solve the problem. It works by spreading infertility genes through a population, which causes a catastrophic drop in numbers over several generations.

A similar approach is already being tested in mosquitoes to help control diseases like malaria and Zika. But now the scientists want to find out if it could also work in mammals.

The technology uses the DNA editing technique called Crispr, a natural process by which bacteria fight off viruses by snipping away at their DNA. The rodents would be genetically modified in the laboratory before being released into the wild where they could mate with the native population.

Prof Bruce Whitelaw, of the University of Edinburgh’s Roslin Institute, where Dolly the Sheep was created, said: “For the first time we have the makings of technology that could reduce or eliminate a pest population in a humane and species-specific manner.

“Crispr is perhaps the most exciting tool that has ever hit biology… It’s time to explore what this technology can do.”

There are thought to be more than 10 million rats living in Britain. Pest control is estimated to cost the UK around £1.2billion each year.

The technique suggested for rodents is known as ‘xshredding.’ Male mammals have both an ‘x’ and ‘y’ sex chromosome, while females need two ‘x’ chromosomes.

The scientists want to insert ‘x shredder’ code into the DNA of male rats which would destroy the ‘x’ chromosomes in their sperm, meaning they could only pass on a ‘y’ chromosome, so their offspring would never

‘Crispr is perhaps the most exciting tool that has ever hit biology’

be female. With fewer and fewer females over time, the population would have to decline.

Gus Mcfarlane, a doctoral student at the Roslin Institute, who will be heading up the project, said: “It is an emerging technology so there are risks involved.

“One of the biggest risks that we’re worried about is if it were to be deployed, we target an animal and it spreads to a non-targeted individual.

“So you target a rat in New Zealand and it makes its way to Asia where it could have unforeseen ecological consequences. But there are mitigation strategies that we could implement if this were to occur.”

The team has published a prospective article outlining the new project in the journal Cell Press.