Catnip turns out to have a hidden effect

(ORDO NEWS) — For many felines, the perennial herb catnip (Nepeta cataria) is an irresistible psychoactive treat that causes short bouts of drooling and squirming with pleasure.

Not content with just rolling among the leaves, many cats tear and crumple the leaves, prompting researchers to figure out the purpose of this senseless extermination.

What appears to be an act of pure hedonism may also have a more medical purpose. Additional leaf damage releases a significant amount of insect repellent compounds into the air by bathing a cat in a natural pesticide, according to a new study.

Although N. cataria is the most common feline intoxicant, a number of plants, including valerian (Valeriana officinalis) and a kiwi species called silvervine (Actinidia polygama), also contain compounds that cause bizarre behavior in domestic and wild cats.

Two such chemicals, nepetalactol and nepetalactone, are figure-of-eight molecules belonging to the class of iridoids, which are produced by plants such as catnip and silvervine to protect against insect attack.

Nepetalactone also excites a number of receptors in the nasal cavity of cats, causing a cascade of reactions that make it impossible to ignore the quick wallow in the leaves.

Previous research has connected the dots, showing that vigorous cat action hits catnip and silvervine leaves hard enough to release enough nepetalactone and nepetalactol, which act as a repellant against Aedes albopictus mosquitoes.

Now, the same researchers wanted to know if biting and chewing brings additional benefits, or if it’s just a sign of a cat’s rampage at the moment of enjoyment.

The study involved 16 healthy laboratory cats who observed their behavior when samples of intact, crumpled and torn catnip and silvervine leaves, as well as iridoid cocktails in petri dishes, were placed in front of their cages.

The team also conducted a number of other tests on the effectiveness of various plant extracts and iridoid mixtures as mosquito repellents, as well as on the concentration of volatile compounds in cat-damaged leaves.

All in all, it became clear that the extra cat damage to the leaves really helped get the party off to a faster start.

“We found that physical damage to silver vines by cats resulted in an immediate release of total iridoids, which was 10 times higher than from undamaged leaves,” said lead author Masao Miyazaki, an animal behavior researcher at Iwate University in Japan.

Not only was the overall concentration higher in both plant species, the mixture of iridoids was more complex in silver vine torn leaves, making them a more potent repellant at lower concentrations.

Cats exposed to these mixtures were also affected for a longer time, suggesting that their biology was “fine-tuned” to maximize doses of silver vine to repel insects.

“Nepetalactol makes up more than 90 percent of the total iridoids in undamaged leaves, but in damaged leaves it drops to about 45 percent, while other iridoids increase significantly,” says Miyazaki.

“A modified mixture of iridoids to match damaged leaves resulted in a much longer response time in cats.”

The use of naturally occurring insecticides stolen from plants and even other arthropods is not something unknown in the animal kingdom.

Not only have we humans brandished chrysanthemum extracts for generations to keep beetles at bay, but lemurs have developed the habit of rubbing centipedes over their bodies as a vermin remedy, and other birds and animals have smeared themselves with citrus leaves for a similar purpose.

However, few of them get the same pleasure from the protective rubbing of the body. These cats seem to be up to something.


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