For many members of the feline family, catnip (Nepeta cataria), sometimes called catnip, is simply irresistible: upon contact they roll, chew, lick, and rub on it aggressively. Nothing new for those who have seen a cat try the precious treat.
This pleasurable quality that catnip gives (catnipin English), and its Asian counterpart, the silver vine (Actinidia polygama), is widely accepted. But beyond seeming like an act of pure hedonism, Japanese researchers now say that this herb also has a practical function, with a medicinal purpose.
According to the new research, published in the journal iScience, cats, by assuming their peculiar behavior, with which they damage the leaves, cause the grass to release significant amounts of insect-repellent compounds into the air. Thus, according to scientists, catnip works as a natural pesticide that protects cats from pests.
Stimulation of receptors in cats
The leaves of catnip and silver vine contain the compounds nepetalactol and nepetalactone, iridoids that protect plants from pests. Nepetalactone is the compound that stimulates a set of receptors inside the nostrils of felines, triggering a cascade of responses that make a quick romp in the leaves impossible to ignore.
Although “N. cataria” is the most recognized catnip, several plants, such as valerian (“Valeriana officinalis”) and a species of kiwi called silver vine (“Actinidia polygama”), also contain compounds that induce strange behavior in domestic and wild cats.
Promote immediate emission of iridoids
To see how cats’ behavior affected chemicals released by plants, Masao Miyazaki, an animal behavior researcher at Iwate University, worked with chemists at Nagoya University.
“We found that physical damage to silver vine by cats encouraged the immediate release of total iridoids, which was 10 times greater than from intact leaves,” says Miyazaki.
According to a press release from Iwate University, in previous work, Miyazaki and his team showed that these compounds effectively repel mosquitoes. Aedes albopictus.
Now the team has shown that when cats damage plants by rubbing, rolling, licking and chewing, the repellent properties are even more effective.
To test whether felines reacted specifically to these compounds, the team used 16 healthy lab cats that were given dishes containing pure nepetalactone and nepetalactol.
“Cats show the same response to iridoid cocktails as they do to natural plants, except they chew them,” says Miyazaki. “They lick the chemicals off the plastic plate and rub and roll on the plate,” she adds.
“Even in the famous musical Cats there are scenes where you see one cat poisoning another with catnip powder,” Miyazaki said.
“When iridoid cocktails were applied to the bottom of dishes that were then covered with a perforated plastic lid, the cats continued to show licking and chewing, even though they couldn’t come into contact with the chemicals directly,” says Miyazaki. “This means that licking and chewing is an instinctive behavior triggered by olfactory stimulation of the iridoids.”
The use of natural insecticides stolen from plants and even other arthropods is not unknown in the animal kingdom. To go no further, humans have been stirring chrysanthemum extracts for generations to keep bugs at bay. Although clearly we are not the only ones.
According to ScienceAlert, lemurs have adapted to rubbing millipedes on their bodies as a form of parasite treatment, while other birds and animals have smeared citrus leaves for similar purposes. However, no one seems to enjoy this protective activity as much as cats.
Edited by Felipe Espinosa Wang.