Mice which had been give the frogs' secretions remained bite-free for up to 50 minutes. Those which had been given DEET, the chemical that is typically used in commercial mosquito repellant, were protected for up to two hours.
But the luckless rodents that had been selected as "controls" and were given neither frog secretion nor DEET, lasted just 12 minutes before their tails were bitten.
Two other Australian species, the desert tree frog (
Litoria rubella) and Mjoberg's toadlet (
Uperoleia mjobergi), were found to give off a mosquito repellent odor from their skin, although their secretions were not tested on mice.
The dumpy tree frog and its slimy secret are not in themselves considered a substitute to DEET, the repellent originally formulated for the U.S. army after World War II.
But the discovery highlights the potential of the unsung properties of amphibian skin, the paper says.
"Many aspects of frog chemical ecology remain unexplored," it points out.
The paper appears in
Biology Letters, which is published on Wednesdays by Britain's Royal Society, the de-facto British academy of sciences.
Frogs and toads have long been known to exude toxic or malodorous chemicals on their skin as a form of protection against fungus and insect pests and to ward off predators.
Previous research has uncovered that these secretions can also be powerful painkillers and hallucinogens. Work is now unfolding to synthesize such molecules so that they can be reproduced pharmaceutically.
