"Love is in air" if you happen to live in a city infested with rats.
After states, like California, restricted toxic rodenticides, some cities are starting to use a more humane way to control the rat population with birth control called ContraPest, the only fertility control for rats approved by the Environmental Protected Agency (EPA).
"[ContraPest] is a ‘milk shake’ for rats. It is a liquid formulation that is high in fat, sweet tasting and very attractive to rats, which need to consume approximately 10 percent of their body weight in water each day," said Ken Siegel, CEO of SenesTech, which is the company that produces ContraPest.
"Deployed in traditional bait boxes, ContraPest targets the reproductive capabilities of both sexes in rat populations, inducing egg loss in female rats and impairing sperm development in males."
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He told Fox News that the birth control does not pose a danger to other animals or people as it is specifically designed for rats, which must regularly consume the product for it to be effective.
The company started to look at the birth control technology after its founders developed a model for inducing menopause in mice, which later became known as "Mouseopause."
But why are rat populations so hard to control?
Two sexually active rats can produce approximately 15,000 "descendants" in just one year, Siegel said.
"Rats reproduce faster than poisons, traps or any other lethal means alone can eliminate them. Without birth control, their population often rebounds beyond its original level within a few months of using traditional rat control methods alone," Siegel added.
Although traditional pest control measures eliminate rats quickly, it only takes two rats for the population to grow back to its original size or even larger within months, according to the company’s website.
Norway rats are the most common rats, but roof rat populations are on the rise in the United States in the last 15 years, Siegel added.
Norway rats live on the ground while roof rats " … often spend their lifetimes never putting paws to the ground," Siegel noted.
So where do you place the tempting bait?
"ContraPest is deployed in traditional bait boxes which is very effective when dealing with the more common Norway rats," Siegel said.
But for roof rats, the bait is placed differently to accommodate their unique living situation.
"Just this week, ContraPest began selling the Elevate Bait System which is a new EPA approved way to deploy ContraPest above ground. It is easily deployed indoors and above ground with multiple options for mounting in the rafters of barns, granaries, storage, manufacturing facilities, attics, and lofts," Siegel told Fox News.
Chicago, New York, San Francisco, Washington, D.C. and Los Angeles are among the top five cities who made the 2021 "rat pack" list for being the "rattiest" places in the United States, according to a press release from Orkin, a pest control service.
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"Most of the rodenticides used today are anticoagulant compounds that interfere with blood clotting and cause death from excessive bleeding. Deaths typically occur between four days and two weeks after rodents begin to feed on the bait," according to the EPA.
First-generation anticoagulants were developed before 1970, but because rodents developed resistance, second-generation anticoagulants were developed beginning in the 1970s, which can kill after a single night's feeding.
The second generation anticoagulants, however, may stay in animal tissues longer than first-generation ones, so they pose greater risks to other animals not targeted who ingest the poison, per the EPA.
This prompted "California [to enact] legislation in January 2021 prohibiting the use of the four major second generation anticoagulant rodenticides under many circumstances," Siegel explained.
"Municipalities are strategically deploying ContraPest along with other more traditional methods of rat control in large public parks, gathering spots and in neighborhoods with high rat activity to accelerate results and prevent rebounding activity," he added.
The company registered ContraPest with the EPA in 2016 as a non-lethal rodenticide for Norway and roof rat population management in all 50 states.
It works alone or in combination with other nontoxic pest control measures, like traps and removing food sources, to reduce rat populations by approximately 90%, Siegel said.
But traditional ways are still the primary methods to control rat populations, according to USA Today.
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"I think in the pest control industry, at least in the U.S., the idea of fertility control, they’ve heard about it, but it’s not widely understood why it’s beneficial," said Brandy Pyzyna, vice president of research and regulatory affairs at SenesTech.
"It does take a lot of education to explain to people why you wouldn’t just kill."