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Studying menopause inspired this Arizona scientist to create open-source, non-lethal rodent control

How do we control rat infestations?

If you’ve ever lived in a big city, you know this can be a problem. One thing is true: Where there is food — and litter — there will be rats. There's New York’s infamous pizza rat, the rats that took over Rome’s famed Colosseum last summer, and even the roof rats in Arcadia right here in the Valley. 

When infestations happen, communities usually put out poison. But, Dr. Loretta Mayer has a different approach that she says has fewer unintended consequences. 

Mayer is a Flagstaff scientist and the co-founder of the nonprofit WISDOM Good Works. She’s trying to change rodent control by controlling their fertility. As she told The Show, it was something of an accidental scientific discovery. 

Full interview

LORETTA MAYER: And that's how most scientific discoveries occur. I was actually working in women's health, and my focus was heart disease in post-menopausal women. And in order to truly understand that, we use animal models and, and these kinds of clinical studies. And I needed a non-reproductive mouse. And typically, that doesn't occur in nature. They're reproductive until the day they die.

So I teamed up with a colleague, Dr. Pat Hoyer, and she was investigating a compound that caused the loss of eggs from the ovary. And typically, that's what menopause is. You have no more eggs. So I was able to do that and reported in American Heart and then got a call from colleagues in Australia actually.

And they basically said, look, you can do this in a mouse. You could probably do something like this in a rat. If we could reduce the population of rats in Southeast Asia alone, we could, just by 5%, we could feed millions of people.

Right. So that's an interesting point to make, right? Like, because you don't think about rats and like the world's food supply, but they, they consume or contaminate a lot of it, right?

MAYER: Oh, yes. When I was in Rome, they told me that they would lose approximately 25% of all the grain that was shipped, like from the United States into northern Africa. And that's food that was just lost.

Yeah, I mean, so that's really interesting because there's that one side of it where, where it's good to control the population of rodents. But then on the other side, like, they're important in keeping a balanced environment, right. Like they can be important in seed dispersal pollination, things like that.

MAYER: Absolutely. Think of the rodent as a link in the food chain. So if you poison that rodent, you're adding poison into the food chain, and then everything up from the chain such as our beautiful raptors and, and mountain lions. So I could, you know, you can just go on, they become poisoned. But the other thing is when those rodents defecate and that gets into the soil, that poison will persist in soil and water. So the issue is they need more tools. And that's why I traded in my white lab coat for some field boots and hit the road to do what I could do.

So, I mean, it's, it's a, it's a funny thing to end up accidentally sort of in like, you know, pest and rat control, but it's important. So, tell us exactly how this works. Like, is it a pellet you feed them? Is it something they eat? How do, how do you get this into their bodies?

MAYER: So, what we have developed now for WISDOM Good Works is little pellets. They're completely organic. I could probably find most of the compounds in your pantry. And they eat these pellets, and as they consume the pellets, they then stop their reproduction cycles. And that takes, so I have thousands of data points on, on these pellets, and they always follow the same pattern. They start eating it, get used to eating, increase and then it decreases down to a low maintenance level. And that's the important part.

You see, when you kill, you're never going to get them all, either they all don't eat it or they're resistant to it, to poison. And so those animals you don't kill, they reproduce at an extraordinary rate. You know, two animals, 15,000 progeny over their eight-month lifetime. Come on.

That's crazy. OK. OK. So, this sounds like it's a more effective way of actually controlling the population of these kinds of pests in the end. Like you're not gonna have nearly as many as you would even if you were trying to kill them.

MAYER: Exactly. But the most important part of this strategy is it's sustainable. You see, if you kill they rebound, and here comes the pest manager again, and then they rebound and they come again. So this just takes them down and holds that level exquisitely low in balance with the environment.

Let me ask you a little bit about the implementation of this. Like you, you've said, you're testing it out. It's being used in various places. It's open source. Now, you've created this nonprofit so that people can essentially adopt this technique, this this formula, right? Where else is it being used?

MAYER: Well, right now, we're using it on the East Coast in Boston. We have done a project in Jamaica Plain. We've done community gardens in zoos. We're trying to test in different locations, animal rescues. We've been invited to the Navajo reservation. We've carried this to the Galapagos Islands.

I think where we are right now is I have enough data, extraordinary amount of data, that we're ready now to make this available to anyone who wants a pilot project. And again, as I said, we're a nonprofit so we don't do the commercial sales, but that's in the works with some very fine partners.

Interesting. OK. So, yeah, tell us a little bit about what's next and where you'd like to see this kind of technology being implemented.

MAYER: We have a project we wanna start in Tanzania,, one in Germany, one in Great Britain and of course back to Southeast Asia. And so I think we're, my vision here and for all of us at, at Good Works, we wanna see people use it. We want to see them embrace the entire concept. We would like to expand to show how not killing, not using a lethal approach to management of any population. You know, whether it's wild deer or elk or stray dogs, that this is the way for us to have a balanced environment.

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Lauren Gilger, host of KJZZ's The Show, is an award-winning journalist whose work has impacted communities large and small, exposing injustices and giving a voice to the voiceless and marginalized.