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To me, there are few more comforting sights on a farm or in a garden than a frog hopping about amid the crops. Frogs and other amphibians don’t just look and sound coolâ€”they also feast upon the insects that feast upon the plants we eat. These bug-scarfing creatures are a free source of what is known as biological pest control.
But modern industrial agriculture doesn’t have much use for them. It leans on chemistry, not biology, to control pestsâ€”and in doing so, it’s probably contributing to the catastrophic global decline of amphibians, a natural ally to farmers for millennia. The irony is stark: in industrial agriculture’s zeal to wipe out pests, it is helping to wipe out those pests’ natural predators. The latest evidence: a new study showing that exposure to common pesticides at levels used in farm fields can kill frogs rapidly.
For a decade or so, it has become increasingly clear that widely used herbicides like Syngenta’s atrazine, in tiny amounts found in streams after running off from farm fields, do crazy things to the sexual development of frogs. Such “endocrine-disrupting chemicals” have what scientists call chronic, not acute, effects on amphibiansâ€”that is, they don’t kill them outright, but they alter them profoundlyâ€”even change their gender. (See Dashka Slater’s profile of a scientist who documented atrazine’s impact on frogs, earning a backlash from Syngenta.) Monsanto’s blockbuster herbicide Roundup also exerts subtle but important harm on amphibians, research suggests.
Again, this research focuses on what happens to amphibians when they encounter agricultural poisons at low levels in ponds and streams. But what happens when they are actually sprayed with chemicals in farm fields? That’s where the new study, a recent peer-reviewed paper by a group of German and Swiss scientists, comes in. They write that the phenomenon of frogs experiencing direct contact with pesticides has been little-studied, even though the scenario is quite common on the groundâ€”farmland has become one of the “the largest terrestrial biomes on Earth, occupying more than 40% of the land surface,” and thus represents an “essential habitat for amphibians.”
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