For many members of the feline family, the perennial herb catnip (Nepeta cataria) is an irresistible psychoactive treat that induces brief bouts of drooling, pawing and squirming pleasure.
Not content with just rolling among the leaves, many kittens tear and crumple the leaves, leading researchers to investigate the purpose of this wanton destruction.
What looks like an act of pure hedonism might also have a more medicinal purpose. The additional damage to the leaves releases significant amounts of insect-repellent compounds into the air, bathing the cat in a natural pesticide, according to a new study.
While N.cataria is the best-known cat intoxicant, a number of plants including valerian (Valerian officinalis) and a type of kiwi called silvervine (Actinidia polygama) also contain compounds that cause odd behaviors in domestic and feral cats.
Two of these chemicals are nepetalactol and nepetalactone — eight-shaped molecules called iridoids that are produced by plants like catnip and silvervine to ward off insect attacks.
Nepetalactone also happens to stimulate a number of receptors in cats’ nasal cavities, triggering a cascade of reactions that make rapid scrolling in the leaves impossible to ignore.
Previous research echoed the points, showing that the cat’s vigorous actions injure the leaves of catnip and silvervine sufficiently to release sufficient amounts of nepetalactone and nepetalactol to serve as a mosquito repellent. Aedes albopictus.
Now the same researchers wanted to know whether the biting and chewing behavior brought additional benefits or was just a sign of the cat’s high spirits.
Sixteen healthy lab cats participated in the study, in which their behavior was observed while samples of intact, wrinkled, and torn catnip and silver vine leaves and iridoid cocktails were placed in Petri dishes in front of their cages.
The team also ran a series of other tests on the effectiveness of various plant extracts and iridoid mixtures as mosquito repellents, as well as levels of volatile compounds around cat-damaged leaves.
Overall, it was clear that the extra damage dealt by ripping the leaves really helped get the party started much quicker.
“We found that cats physically damaging silver vines promoted immediate emission of total iridoids that was 10 times higher than intact leaves,” says lead author Masao Miyazaki, an animal behaviorist at Iwate University in Japan.
Not only was the total concentration higher in both plant species, the mix of iridoids was more complex in torn silver vine leaves, resulting in a more potent repellent at lower concentrations.
Cats exposed to these mixtures were also affected for longer, suggesting their biology was “fine-tuned” to maximize silver vine’s insect repellent doses.
“Nepetalactol accounts for over 90 percent of the total iridoids in intact leaves, but this drops to about 45 percent in damaged leaves as other iridoids increase sharply,” says Miyazaki.
“The altered iridoid mix, which corresponds to damaged leaves, promoted a much longer-lasting response in cats.”
The use of naturally occurring insecticides stolen from plants and even other arthropods is not unknown in the animal kingdom.
Not only we humans waved chrysanthemum Extracts have been around for generations to keep the bugs in check, lemurs have adapted to rubbing centipedes over their bodies as a form of parasite treatment, while other birds and animals have anointed themselves with citrus leaves for similar purposes.
Still, few seem to get the same pleasure from her protective body rubs. These cats seem onto something.
This study was published in iscience.