Pest control companies routinely use traps baited with rodenticide to kill rats and mice found in homes, restaurants, and businesses throughout the Philadelphia area, but a recent Rutgers University study suggests those companies face a gnawing problem.
Researchers discovered that mice in Philadelphia, Trenton, and suburbs like Levittown and New Hope harbor genetic mutations that shield them from standard chemical baits.
In fact, a majority of house mice sampled from Northeast urban areas, including Manhattan and other New York City boroughs, carried at least one mutation linked to rodenticide resistance — a clear sign that pests are actively evolving to survive common poisons.
Rats presented a different problem. While they lacked the chemical-resistant mutations found in mice, the study’s author suggests they possess the cognitive sophistication to outsmart and evade traps entirely.
Lead author Jin-Jia Yu, a postdoctoral researcher in Rutgers’ entomology department, said the findings indicate that pest control companies might need to develop different strategies.
Yu conducted his research with the supervision of another of the paper’s authors, Changlu Wang, an entomologist in the same department.
Published in the April issue of Pest Management Science, the peer-reviewed study was launched after frustrated pest control professionals repeatedly approached the Rutgers lab, reporting that rodents routinely survived multiple treatments.
“For the house mouse, we saw much more mutations rather than Norway rats,” Yu said. Norway rats are the common brown rat often seen in sewers. “Genetic mutation is not that special in these creatures. But we found that the house mouse shows a lot of genetic mutations related to rodenticide resistance.”
Rodents are a bigger problem in cities
This study focused on urban rodents. It found that mice in big cities such as Philly and New York had a high frequency of mutations of a certain gene.
Rodents are a bigger problem in cities than more rural areas. Data cited in the study indicate that an average of 12% of all households experience rodent sightings. But major metropolitan areas reporter higher rates, including Philadelphia (29%), Washington (20%), and Manhattan (15%).
Yu said that similar studies of mutations in house mice and Norway rats were conducted in Europe and that research in the U.S. has been limited. One study in 2009 did find some rats in England with mutations that made them resistant.
However, Yu said there had been no such studies in the Northeast.
It has long been known that rodents developed resistance to the rodenticides developed in the 1950s. So more potent compounds were created in the 1970s and include brodifacoum, bromadiolone, difenacoum, and difethialone.
The poisons contain anticoagulants that interfere with the activation of vitamin K reductase (VKOR), an enzyme essential for blood to clot. Eating the bait leads to fatal internal bleeding.
The Rutgers team looked for mutations in the gene known as VKORC1 that makes the enzyme.
Pest control companies, as well as the Philadelphia Department of Public Health, sent the researchers the tails of caught rodents. Yu said his research was possible only with their help.
A rare mouse mutation in Philly
The researchers analyzed DNA from 147 house mice and 143 Norway rats collected in New York, New Jersey, Pennsylvania, and Washington, D.C.
Among house mice, 84% carried at least one mutation in the VKORC1 gene. Nearly 70% carried mutations known to help mice survive rodenticides.
Of 24 mice collected in Philadelphia, the majority had a mutation and five had two. One mouse had a rare mutation.
Of 20 mice collected in Trenton, 10 had two mutations. Lansdale, Levittown, and New Hope had one mouse each with a mutated VKORC1 gene.
About 35% of the Norway rats also carried mutations. However, scientists do not yet know whether those mutations result in resistance in the rats.
Mice, Yu said, might be genetically adapting faster than rats because they are curious and more likely to eat unfamiliar food, including rodent bait.
However, rats will avoid new objects, including live traps, and learn from their encounters.
In other words, not only are mice mutating to survive, but rats may be learning to avoid entrapment.
“They’re pretty smart,” Yu said of rats.

With protein hogging the spotlight lately, it may seem as if it’s the main nutrient to focus on when it comes to good health. But fiber deserves attention too, nutrition experts say.
Most Americans, while eating plenty of protein, aren’t meeting fiber recommendations — which are 25 grams per day for women and 38 grams per day for men.
Few foods offer both nutrients, said Cheryl Anderson, a professor and dean of public health at the University of California, San Diego. Animal products that are high in protein, like beef, fish and chicken, often contain no fiber. And foods that are high in fiber, like fruits and vegetables, typically offer little protein.
The sweet-spot foods that contain both nutrients offer a nice one-two punch of benefits, Dr. Anderson said. Not only are they often satiating and inexpensive, she said, but you get both the protein perks, like muscle maintenance, and the fiber perks, like improved gut health and reduced risks of chronic conditions, all in one bite.

A man was taken into custody after leading police on a multi-county chase Sunday afternoon.
Porter County officers stopped a blue Nissan in the area of 450 E and US Highway 30 because its license plate indicated it was stolen.
The Nissan, driven by 28-year-old Keon Starr, fled from the scene, continuing eastbound on US Highway 30 into Starke County.
Police say Starr was believed to have been traveling at speeds of up to 100 mph.
Starke County deputies deployed stop sticks at US 30 and State Road 23, successfully deflating the rear tires just before 3:30 PM.
The vehicle came to a stop in the area of 1100 East and US Highway 30.
Starr was taken into custody by Porter County Police on felony charges of Auto Theft and Resisting Law Enforcement.
This is a developing story. Stay with WSBT 22 News as we work to learn more.

(NEXSTAR) – The number of people living with Alzheimer’s disease is expected to double by 2060. New research is shedding light on warning signs and risk factors that could signal cognitive decline ahead.
One clear risk factor, the research shows, is hearing loss.
“We know from a lot of public health studies that hearing loss changes the brain, and we have also seen in studies that hearing loss is consistently linked to a higher risk of dementia over time,” said Jennifer Deal, an associate professor of epidemiology at the Johns Hopkins Bloomberg School of Public Health, in a recent media briefing on Alzheimer’s.
It’s not just about volume, Deal said, but rather about hearing clarity.
“So you can hear someone speaking, but the words kind of blur together,” she explained. “So, the word sphere, S-P-H-E-R-E, for example, may sound like the word ear, E-A-R.”
It’s not clear exactly how hearing loss and Alzheimer’s are connected, Deal said. One possibility is that hearing issues could make it harder to connect socially, and social isolation could make cognitive decline worse.
Intervention – like using a hearing aid – could be helpful in fighting off dementia, but the research is mixed, Deal said.
Hearing loss isn’t the only risk factor that appears in the research.
“It is not one single factor that is contributing to that risk,” said Adam Spira, a professor in the Department of Mental Health at Johns Hopkins. “There are a whole range of factors that play a role.”
Another important risk factor, Spira pointed out, has to do with sleep. “We now believe that sleep disturbances, such as not getting enough sleep, having your sleep be of poor quality, more fragmented (sleep) over the course of the night – those sorts of disturbances are risk factors for cognitive decline and dementia, according to the developing research literature.”
Sleep apnea, a common condition that obstructs breathing while sleeping, may also increase people’s risk of developing dementia and Alzheimer’s, Spira said.
Other risk factors, according to Spira, include cardio-metabolic problems, hypertension, diabetes, obesity, depression, traumatic brain injury, and low physical activity.
As the research unfolds, it’s becoming clear there is no “magic bullet for dementia prevention,” Deal said.
“We really need to probably be tackling a number of different factors in order to move the needle.”

Dementia is poised to hit more Americans than ever, but the odds are quietly shifting in your favor. Vox’s Bryan Walsh reports that while a graying population means new dementia cases in the US could top 1 million a year by 2060, a person at any given age is now far less likely to develop the condition than someone that age a generation ago. Across rich countries, age-specific dementia rates have fallen roughly 13% per decade since the late 1980s, with similar drops for Alzheimer’s specifically.
What’s driving the improvement? Walsh points to better heart and blood vessel health—think blood pressure and cholesterol drugs, less smoking, and improved stroke care—as well as more years of schooling, which research has linked to lower dementia risk, though without pinpointing why. A 2024 Lancet commission estimated that tackling 14 midlife risk factors, from high LDL to hearing loss to inactivity, might prevent or delay up to 45% of cases, and Walsh flags the intriguing (but still early) evidence that the shingles vaccine may reduce dementia risk. His view? Some of us will undoubtedly develop dementia. “But that doesn’t mean we’re helpless.” Read his full piece here.
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