Cats are so often a mystery even to those who know them best. Why do they sleep so much? Why do they want all your attention in one minute and nothing in the next? How to find your way back At home after being blocked for miles on years? Writer Haruki Murakami, who is known for putting cats in his novels and essays, once admitted not knowing why he does it; a cat “naturally gets in,” he said.
Another mystery: Why do cats love catnip? When the plant, which is associated with mint, is exposed to the majority domestic cats will lick it, rub it, chew it and roll it. They are filled with euphoria, inflating things. They are also wild for other plants, especially the silver vine, which is not closely related to the cat herb, but elicits the same response from cats, including large cats such as jaguars and tigers.
For years, this behavior was just another enigma about cats. But a new studypublished Tuesday in the journal iScience, suggests that the reaction to catnip and silver vine can be explained by bug repellent effect of iridoids, the chemicals in plants that cause high.
Researchers led by Masao Miyazaki, an animal behavior scientist at Iwate University in Japan, found that the amount of these iridoids released by the plant increased by more than 2,000 percent when the plant was damaged by cats. So perhaps a kitten’s high level gives it an evolutionary advantage: keeping blood-sucking insects at bay.
Christine Vitale, a cat behavior expert at Unity College who was not involved in the study, said the study was based on strong previous work. Last year, the same lab published a study that found this cats would do everything possible to cover themselves with iridoids similar to DEET, whether by rolling on chemicals or by getting up to press them with your cheeks. “This shows that there may be benefits for a cat that physically puts the compounds on its body,” said Dr. Said Vitale.
Carlo Syracuse, an animal behaviorist at the University of Pennsylvania who also did not participate in the study, agreed. “Evidence shows that they want to impregnate their bodies with the smell,” he said. But, he added, “keep in mind that most cats do not show this behavior. So why would they be elected that way? “
As an evolutionary adaptation, bug-repellent iridoids they probably do more to protect plants from herbivorous insects than to help cats avoid insect bites. Plants often release irritants when they are damaged, which helps repel attackers, and they release other chemicals that report danger to their neighbors. “Plants are masters of chemical warfare,” said Marco Gallio, a neurobiologist at Northwestern University who was not involved in the new study.
Last year, Dr. Gallio and his colleagues published a report which binds the main insect repellent in catnip, nepetalactone, to a receptor protein that causes irritation in mosquitoes and related insects. The receptor, which is also present in humans and cats, can be triggered by tear gas. But Dr. Gallio finds that although nepetalactone has no adverse effects on humans and drives cats into ecstasy spasms, it activates this particular receptor (called TRPA1) in many insects – an added bonus for cats rolling in their chosen drug .
In his latest study, Dr. Miyazaki and his collaborators measured the chemical composition of the air just above the leaves – intact and damaged – of catnip and silver vine. They then measure the iridoid levels in the leaves themselves. They found that catnip leaves damaged by cats released at least 20 times more nepetalactone than intact leaves, while damaged silver vine leaves released at least eight times more similar iridoids than intact leaves. The interactions of cats with the silver vine also changed the composition of the insect repellent cocktail of the plant, making it even more powerful.
After rubbing their faces and bodies in the plants, the cats will certainly be covered with a strong layer of Pest Begone.
This discovery, combined with Dr. Miyazaki and his previous research report support emerging claims that at least part of the benefits of catnip mania are repelling mosquitoes and flies. Such behavior, called “self-anointing,” would not be the first of its kind in the animal kingdom. It is known that Mexican spider monkeys they are spread with different types of leaves, probably for social or sexual purposes, and often hedgehogs rub the toxins on their spines.
However, many questions remain to be answered, including why only cats seem to have a euphoric reaction to catnip and silver vine, and why only some of these cats do. Dr. Gallio, although enthusiastic about the new study, proposed a cautious approach. “What do I know?” he said. “I wasn’t there to see evolution unfold.”