Genetic modification key to controlling rat population?

Genetically modifying male rats so they only produce male offspring could help solve Toronto’s rodent problem, which experts say worsened in the last year.

These mutated male rats would reduce the number of breeding females and slash the population without the use of poisons — substances to which the rodents are now building up a resistance.

“2018 wasn’t a great year. It definitely seemed to be worse and they migrate everywhere,” said Brian Martin, of Orkin pest control, who has heard of the practice of mutating rats, but says it’s not being done in Canada.

“I will look for it (gene modification) in the future. As many tools we have in our tool box will help.”

The project to genetically edit rats comes from Edinburgh University where Dolly the cloned sheep was created. The rats would be modified in a laboratory to eliminate the x chromosome in the sperm needed to produce females and then released into cities to mate with the native population.

Pest controllers are limited by Health Canada as to what poisons can be used so children and dogs don’t come into contact with them and get sick, said Daniel Mackie, with Greenleaf pest controllers.

“In theory, it would work well and slow the population, but then another male could migrate so there is no silver bullet with rats. New rats will come in. You would have to quarantine or Donald Trump the entire area with a wall,” Mackie said.

“I think you have to research this type of birth control approach. What if one of these rats gets eaten by a cat or a hawk and this birth control trait gets passed on.”

She added researchers are now finding cases of rats which ingest and survive poisons so it may be time to look at the alternatives.

The life span of a rat is only a year so genetic modification may have some success, said Jason Munshi-South, a professor of biology and rat expert at Fordham University in the Bronx, where garbage bags are regularly moved around by feeding rodents.

“People have a tendency to look for a magic solution. This could take, maybe several generations. If it worked fast enough, it could have a positive effect,” Munshi-South said.

In the spring of 2018, Toronto city council voted to approve a plan to have the medical officer of health and municipal licensing division come up with a rat control plan. Nothing has yet come forward.

The infertility gene drive could solve the problem and take deadly poisons out of the equation, said veterinarian Jamie Rothenburger, a professor of anatomic pathology at the University of Calgary.

With the Rocky Mountains to the west and vast stretches of buffer-zone prairie lands to the east, Alberta is the only province that’s rat free.

“It’s astounding how the Alberta rat police have been able to stop the invasion from Saskatchewan,” said Rothenburger, who has studied rats for seven years.

“A rat’s reproductivity is incredible and not having them is a huge savings to urban infrastructure,” Rothenburger said, adding rats are a destructive pest.