Cats rub their bodies on silver vine leaves, also known as matatabi in Japan, to protect themselves from mosquitoes, which are known to carry viruses.
A team of researchers from Iwate University and other institutions has concluded that cats rub themselves with silver vine to repel mosquitoes. It was discovered that a chemical substance on the plant attaches to the fur, and it functions similarly to a mosquito repellant. The study was published in the digital version of the U.S. scientific journal Science Advances.
When cats find silver vine, they rub their faces against it or roll on the ground with it. Such responses have been observed since the Edo period (1603-1868), but the exact reason why cats prefer silver vine was unknown.
Masao Miyazaki, a professor specializing in molecular biology at Iwate University, and other researchers found that chemicals contained in certain plants, which are preferred by cats in Europe and the U.S., is effective to repel mosquitoes.
The team succeeded in extracting nepetalactol, which has a similar structure to the chemical substances found in the plants in Europe and the U.S., from silver vine leaves.
They conducted an experiment comparing cats with nepetalactol on their heads and cats without the chemical, placed them all in a cage and released 30 mosquitos. The results showed the number of mosquitoes that landed on the cats with the chemical was reduced by half.
Further experiments also confirmed that as the cats reacted to silver vine, neurotransmitters were released in their brains, activating the section responsible for creating a sense of euphoria.
The same response was observed when large felines such as leopards and jaguars were given nepetalactol.
"Rolling around is not just a sign of happiness, but is probably an instinctive behavior passed down through evolution," said Prof. Miyazaki.
Kazushige Tohara, a professor of biochemistry at the University of Tokyo, said: "It is a logical conclusion to suggest that a cat's reaction to silver vine is to use it as a mosquito repellant. It is an achievement that could answer a long-standing mystery."
Read more from The Japan News at https://japannews.yomiuri.co.jp/
