Pesticide pollution actually creates toxin-tolerant frogs—to a point

Tequila is rarely touted for playing a role in good decision-making, but a wacky idea Jessica Hua hit on over margaritas a few years back turned out to be a stroke of genius. At the time, Hua was a PhD student at the University of Pittsburgh, working with Rick Relyea, a biologist who has extensively studied amphibians and pesticides (the toxins are often implicated in the decline of amphibian populations worldwide). When it comes to pests, resistance to the chemicals intended to kill them is a well-known problem. But it’s not just weeds and insects that are able to withstand the poisons—Relyea’s work had shown that lethal doses of pesticides didn’t always kill all frogs, either. The standard explanation would be that over many, many generations, some hoppers had developed the ability to tolerate the toxin, and their offspring were born with immunity. But that night, Hua had a different thought: What if exposure to a little bit of pesticide at a young age made the creatures better able to withstand doses of the toxic stuff later in life? In other words, what if any frog could become pesticide-resistant? Her lab mate encouraged her to pitch the idea to Relyea, so she did—later, in the light of day. “I said, ‘That’s crazy,’ ” laughs Relyea, who is now at Rensselaer Polytechnic Institute. “I’d never heard of any animal that could induce tolerance. But she came right back and said there was one example: a mosquito.” With that, Relyea gave her the go-ahead, so Hua’s very first step was to collect eggs from wild frogs as soon as they were laid...more