‘Invincible super rats’ are taking over US cities – and it may be our fault, experts say
SUPER rats are plaguing cities around the country, and it doesn’t look like they’ll stop any time soon.
Cities like New York and Chicago have used extermination crews, so-called "rat perfume" and even booze to fight vermin - but poison could be the reason they continue to thrive.
Unlike your typical rodent, these genetically mutated rats are larger than average and resistant to conventional rat poisons.
Short-term rat control campaigns can have a Darwinian effect on vermin populations in populous cities.
Though most colonies are successfully wiped out, says the surviving population is more “fit” for evolution and therefore likely to have certain traits to protect them from the next onslaught of poisons.
These “super rats” then produce more baby rats which inherit the same traits, according to University of Richmond biology professor and rat expert Jonathan Richardson.
"If only the fittest rats make it through the control campaign, the survivors may be even better adapted to take advantage of the high-resource minefield of modern cities, leaving a new population of "super rats to breed and repopulate," he said.
Scientists have even found specific versions of in mice and rats that have developed as a response to half a century of pest control use.
"These beneficial gene variants have been observed in some natural populations of rats regularly exposed to poison," according to Richardson.
The biggest roadblock to stopping super rats is the under-funding of pest control programs or in some cities, a lack thereof.
But even when cities do spend the money on vermin control, it’s not guaranteed that the effects will balance out the costs.
In 2017, New York City Mayor Bill DeBlasio announced a $32 million initiative to kill rats, but it would only reduce the rodent population in the city’s most infested areas by 70 per cent, the reported.
Additionally, most poisons are not species-specific and often end up bioaccumulating, or becoming highly concentrated, in the animals that remain.
However, inbreeding between super rats can sometimes have the opposite effect and cause a genetic bottleneck, creating sickly rats.
A 2016 study of Norway rats in Salvador, Brazil found that rodents can rapidly lose much of their genetic variation during a lethal rodent control campaign.
This variation is the key to super rats’ survival because it allows them to better adapt to changing environments via natural selection.
Experts believe that the key to fighting super rats is using different methods of pest control such as dry ice and even rat birth control, as the said its namesake city did in 2017.
However, they say the most effective way to fight off urban pests is also the most simple - better trash disposal and rodent-proof garbage cans.
Researchers found that rats were attracted to areas sprayed with a so-called "rat perfume" containing female pheromones and visited them more than areas with male pheromones, according to the .
MOST READ IN US NEWS
Their study argues that using pheromone technology as rat control is much more effective than conventional rat traps because it's nearly impossible for rodents to develop an immunity against pheromones even with repeated exposure.
An alcoholic rat-dunking device was unveiled in New York City in September.
The device, called Ekomille, baits rodents with food, then drops them through a trap door into a non-toxic alcoholic solution that knocks the rats unconscious and eventually drowns them.
Ekomille can hold up to 80 rat carcasses in its built-in bucket.
An estimated 2 million rats live in New York City, which equals about 25% of the city's 8 million residents.