Rats and mice in major American cities are developing genetic mutations that make them harder to kill with common poisons, according to new research from Rutgers University.
Scientists examined nearly 300 rodents from New York, New Jersey, Pennsylvania and Washington, D.C., and found widespread signs of resistance to widely used exterminator chemicals.
Around five out of every six rodents tested carried at least one mutation linked to reduced sensitivity to poison.
More than two-thirds also had additional genetic changes previously tied to resistance against common rodenticides.
The mutations were especially common in house mice, which researchers said appear to be adapting faster than larger brown rats, also known as sewer rats.
“Genetic mutation is not that special in these creatures,” lead researcher Jin-Jia Yu said. “But we found that the house mouse shows a lot of genetic mutations related to rodenticide resistance.”
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