Scientists use sex, food, sound to lure rats in superior trap

Scientists have outwitted the crafty rat with a stimulating new formula that puts sex on the brain.

A team at Simon Fraser University in Burnaby, B.C., has developed a rat trap that combines synthetic sex pheromones, food scents and baby rat sounds to lure rodents to their deaths.

The bait has proven 10 times more powerful than traditional traps and could be commercialized in about two years, said principal investigator Gerhard Gries.

"Rats are really intelligent, and in order to manipulate them you have to be intelligent as well, and do that in a way that addresses their needs," said Gries, a communication ecologist in the department of biological sciences.

"It smells delicious, it smells like rat and it sounds like rat."

Research outlining the pheromone component of the control tactic was published last week in the international edition of the German peer-reviewed online journal Angewandte Chemie,which translates to "Applied Chemistry." The research on the use of baby rat sounds was published recently in the journal Pest Management Science.

Gries worked for several years with research associates Stephen Takacs and Regine Gries, his wife, to develop the three-pronged extermination technique.

Humans have waged war against the pests for more than 10,000 years, said Gerhard Gries, noting they spread disease, reduce agricultural crop yields and threaten endangered animal species.

But rats are quick learners that have evolved to avoid traps, a behaviour called "neophobia," he said.

The new trap overrides rodent smarts using a synthetic sex chemical that replicates the pheromones, or chemical messengers, of sexually mature male brown rats. It's a powerful attractant for female brown rats, Gries said.

Also blended into the bait are aromas of food sources most craved by rats, such as nuts, cheeses and cereals, and electronic sound recordings of rat pups. The fabricated cries trigger the maternal instinct in female rats, Gries said, while male rats will approach the bait believing they've discovered a meal.

The trap is styled like a traditional bait box and contains a mechanical snap trap that breaks the rodent's neck. Its "appealing message" works so efficiently on rats that consumers don't need to reset the trap multiple times, Gries said.

"By speaking their language, we can manipulate them or guide them to locations where we can kill the responding rat," he said.

The team is hoping to commercialize the new trap with its industrial sponsor Scotts Canada Ltd. Its research was conducted under Canadian Council on Animal Care guidelines.

'Earth-friendly' option

Gries said his primary motivation for developing the advanced trap is to reduce reliance on poison bait stations. Rats that consume poisoned bait bleed to death, Gries said, impairing their movement so they become easy targets for wildlife including owls, foxes, coyotes and big cats.

Such predators become sick feasting on the poisoned rats, creating deadly reverberations throughout the food chain. Gries said the new trap is an "earth-friendly" option that kills the rat instantly.

"If we accept the premise that we don't want rats in and around our homes because they do all kinds of damage," Gries said, "then there is only one solution."

What's more, Gries doesn't believe the new trap can be outsmarted.

"The rat that has responded to your pheromone message or sound message has really been killed, it cannot transfer that message," he said.

"There's no learning effect passed along to next generation."

• Bedbug bait and trap invented by Simon Fraser University scientists