Here in St. Louis, the mosquitoes seem to buzz around longer into the fall than they used to. West Nile virus cases (see cool map from Centers for Disease Control) have been reported often over the past month. Meanwhile, frogs are eerily going silent aa they face a mass extinction (the aversion of which is the mission of Amphibian Ark). Is there a connection?

I posed the question to entomologist Joseph Conlon, who is a technical advisor to the American Mosquito Control Association. His take? There isn’t much of a connection:

“There have been a few anecdotal reports of tadpoles consuming mosquito larvae in containers, probably a result of having no other food sources.  I’m aware of no published field studies that would establish this as a norm, though.  Adult frogs, as you are aware, will consume anything that comes their way and, no doubt, mosquitoes sometimes fall prey to them.  Whether they constitute even a marginal control on mosquito populations is rather problematic.  An overnight camping visit to the Florida Everglades, which has a burgeoning amphibian population, would tend to convince anyone (who has been nearly exsanguinated) to downplay their role in mosquito population dynamics. That being said, frogs are cool – and beautiful in their own right.  Whatever is causing their decline should be studied with an eye toward finding a way to reverse their fortunes.  Unfortunately, anti-pesticide activists are using this issue as a way to (quite wrongfully – and without a shred of scientific merit) advance their agenda.  Hopefully, cooler scientific minds will prevail and a way will be found to reestablish amphibian roles in the eco-community.”

But Kraig Adler, PhD, in a comprehensive article about amphibians, writes that:

“The international trade in frogs’ legs is enormous and mostly originates in southern Asia and the East Indies. The wild capture of so many frogs, which are insectivores, has resulted in growing populations of mosquitoes and other insects in these countries.”

So, the anecdotal answer from the Everglades is that the connection is slight; the evidence from Asia is, yes, there’s a connection. And just when you want to call it a stalemate, you learn that the amazing skin of frogs could hold the key to new, powerful mosquito repellents. Talk about changing the debate. The University of Adelade tested the  secretions from the dumpy tree frog on mice; those mice were bite-free four times longer than mice that were offered no protection.  The researchers summarized: “The discovery highlights the potential of the unsung properties of amphibian skin.” Here’s the full story.

About these ads