Amphibian answer to mosquito peril
A bottle-green Australian frog may hold the key to a next-generation mosquito repellent, according to a scientific paper that appeared.india Updated: Feb 23, 2006 12:01 IST
A bottle-green Australian frog may hold the key to a next-generation mosquito repellent, according to a scientific paper that appeared today. Scientists are marvelling over secretions exuded by the dumpy tree frog, Litoria caerulea, a species that inhabits forests in northern Australia and New Guinea.
Using a small electrical current, they gave a gentle zap to a frog, causing smooth muscles in its glistening skin glands to contract and secrete the fluid that covers its skin. The secretions were washed off with distilled water and applied to the tails of lab mice.
The mice were then exposed to dozens of Culex annulirostris mosquitoes – an aggressive Aussie mozzie notorious for transmitting encephalitis among other diseases. Mice which had been given 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. Two other species, the desert tree frog, Litoria rubella, and Mjoberg’s toadlet, Uperoleia mjobergi, were found to have a repellent odour from their skin, although their secretions were not tested on mice.