No one knows exactly how many rodents reside in New York, but by some estimates, there may be as many rats as humans. What’s more, rats are remarkably fertile, sometimes birthing 12 pups per litter and as many as seven litters in a year.
New York’s rats may not be so fecund for long: The Metropolitan Transport Authority has kick-started a pilot program to sterilize female rats. To do this, it is teaming up with Flagstaff (Ariz.)-based SenesTech, a company that invented ContraPest, a product that, when consumed orally by rats, accelerates egg loss and can cause infertility in days. (The company’s name comes from the world “senescence,” which means to age.)
New York’s rat extermination proposals in the past have included everything from the deployment of World War I-era poison gas to a hunting spree led by rifle-bearing citizens. (The gas was used with some success on Riker’s Island; the hunting party was apparently called off at the last minute). This seems to be the MTA’s first effort to target the rodents’ reproductive organs.
For the next couple of months, SenesTech will study rat behavior in New York ‘s subways. One goal is to pinpoint preferred foods in hopes of making the ContraPest bait more desirable than such other goodies as discarded pizza and candy. “Here in New York, rats have such a buffet available to them,” says SenesTech Chief Executive Officer Loretta Mayer, “but they don’t necessarily get a lot of liquid, which is why we’ll be offering them … a semi-solid covered in kind of a cheese wax and also liquid from a bottle feeder—They’ll have a bite to eat and a glass of wine, you know?”
Mayer says ContraPest is made up of mostly salt, sugar, fat, and two active ingredients—an industrial chemical and and an herb. The product will be placed inside bait boxes outfitted to monitor rat traffic. The boxes will be set up in locked subway platform trash rooms, where garbage is kept until trash trains take it away.
The overall goal is to diminish rat populations—but not wipe them out entirely because that would simply cause an influx of new rats. “Rats are territorial, so you want to maintain a very low population that keeps other rats from migrating in,” says Mayer. “That way, you won’t have an infestation, you won’t have an outbreak, you’ll manage them so low that folks won’t see them on the subway tracks any more. ”
Mayer estimates that only two or three rats are needed in each 200-square-foot subway trash room to keep out new rats, and she says the overall goal is to reduce the current population by as much as 75 percent. Once the target numbers are achieved, SenesTech will remove the bait from its boxes.
SenesTech, founded in 2002, is already running tests in Indonesia, Laos, the Philippines, Australia, and New Zealand, mostly in agricultural areas. The goal in those areas is to keep rodents from devastating crops such as wheat and rice. The company, which regards the technology as the first of its kind, is also in the early stages of developing a product to sterilize dogs.
Mayer says ContraPest does not work on people—perhaps because humans have developed superior detox capabilities—nor does it pose any danger. She says that rats metabolize the compound into inactive ingredients within 15 minutes of consumption, rendering rat excretion innocuous. “And should the compounds spill and be exposed in the environment … it also breaks down into inactive ingredients,” she says.
ContraPest also doesn’t appear to cause noticeable rat mood swings, says Mayer. “As one person said to me, ‘Wow, don’t you worry? I mean a whole bunch of large menopausal rats—aren’t they angry?’ Well, we’ve not seen that behavior change.”
