Our amphibians are not doing well. Populations of frogs, toads, salamanders and newts the world over are falling dramatically. Their moist, permeable skins and their need for water to reproduce make them vulnerable to a multitude of threats including drought brought on by climate change, a deadly fungus, and other infectious diseases. Now, we can point an accusatory finger at another culprit – a chemical called atrazine that is second most commonly used pesticide in the United States, and perhaps the world.

Rohr discovered this tangled web by studying the northern leopard frog, a North American species that, like most of its kin, is in decline. Across 18 wetlands in Minnesota, Rohr looked at local frogs, the parasites