Mutant rats with disturbing 'DNA changes' discovered in sewers under major US cities
Rodents in the US are going rogue and it's making it even harder for officials to stop them overrunning major cities.
It is common knowledge that there is a massive pest problem across the pond - and this recent scientific discovery might explain why it's so difficult to get rid of them.
Researchers have discovered that rats and mice have genetically mutated and may have become resistant to the commonly used poisons that helps keep the growing number of them at bay.
Experts are calling for authorities to implement more 'science-based management strategies' to get the rodent crisis under control in wake of the results of a recent study.
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For those who are unaware, some of the most alluring cities in the US are ravaged by rats and mice.
According to last year's edition of the Top 50 Rattiest Cities list by pest control company Orkin, Los Angeles is the place that is worst off.
Chicago, New York, San Francisco, Hartford, Conn, Washington D.C, Detroit, Philadelphia, Minneapolis, and Denver made up the rest of the top 10.
The rat and mice population of the US has only continued to swell over the last year and researchers now reckon they might have an idea why.
Experts at Rutgers University in New Jersey took a look at the 'growing challenge' of rodent management.
They got hundreds of house mice and brown rats, which are also dubbed sewer rats or Norway rats, from urban areas and conducted some analysis to see why they are so difficult to quell.
A whopping 84% of the 147 mice and more than a third of the 143 rats involved in the study were found to carry at least one genetic mutation in the gene Vkorc1 that suggests they are now resistant to rodenticide.
The research, which was published in the journal Pest Management Science, explains: "Five nonsynonymous single nucleotide polymorphisms (nsSNPs) were identified in house mice, including A32V, W59L, L128S, Y139C, and Y139F. Among all mice examined, 84% carried at least one mutation, with Y139C (42%) and L128S (33%) being the most prevalent.
"At least 69% of the mice carried mutations that are known to confer resistance. In Norway rats, 35% carried mutations including two synonymous mutations (H68H, I82I) that have been previously reported and one nsSNP (L128V) that was newly identified in this study. However, H68H is not associated with AR resistance and whether the other two mutations contribute to AR resistance remains unknown."
Anticoagulant rodenticides (ARs) are typically used by authorities to help control rodent populations, but it seems they are now adapting so that these chemical agents no longer prove fatal.
"The development of resistance driven by mutations in the Vkorc1 gene has become a growing challenge in rodent management," the researchers said.
Jin-Jia Yu, a postdoctoral fellow at New Jersey’s Rutgers University, explained that pest control professionals were complaining that 'rodent control was becoming more difficult in some areas, even though they applied the effective rodenticides'.
"I wanted to find out whether this was occurring in the northeastern United States, especially the metropolitan areas, and how widespread the problem might be," the expert said in a statement.
“We found that resistance appears to be much more widespread in house mice than many people realised.
"Norway rats also carried genetic mutations, but scientists do not yet know whether most of those mutations affect Norway rats' susceptibility to rodenticides.”
'Rodents are more than a nuisance'
Yu reckons that the study has provided some of the 'first information on rodenticide resistance in the northeastern United States'.
"By understanding how prevalent the mutations are and where resistance exists, pest management professionals and public health agencies can make better decisions about how to control rodents," Yu added.
Changlu Wang, an extension specialist in Rutgers’ Department of Entomology, said that it's a good job they clocked onto this, as the resistance could have implications for public health.
"Rodents are more than a nuisance," Wang said. "As resistance becomes more common, it becomes even more important to use science-based management strategies that protect both public health and the environment."
Olivia Burke