For many members of the feline family, perennial catnip (Nepeta cataria) is an irresistible psychoactive treat that induces short bursts of drooling, pawing, and writhing pleasure.
Not satisfied with simply rolling among its foliage, many catkins will tear and wrinkle the leaves, prompting researchers to investigate the purpose of this wanton destruction.
What appears to be an act of pure hedonism could also have a more medicinal purpose. According to a new study, the additional leaf damage releases significant amounts of insect-repellent compounds into the air, bathing the cat in a natural pesticide.
Whereas N.cataria is the most commonly recognized cat intoxicant, a number of herbs including valerian (Valerian officinalis) and a species of kiwi called silver vine (polygamous actinidia) also contain compounds that induce strange behaviors in domestic and feral cats.
Two such chemicals are nepetalactol and nepetalactone – figure-eight molecules classified as iridoids, which are produced by plants like catnip and silver vine to ward off insect attacks.
Nepetalactone also happens to tickle a set of receptors inside the nasal cavities of felines, triggering a cascade of responses that make a rapid rolling in the leaves impossible to ignore.
Previous search joins the dots, demonstrating the vigorous actions of the cat bruising the leaves of catnip and silver vine enough to release sufficient amounts of nepetalactone and nepetalactol to act as a mosquito repellent, Aedes albopictus.
Now, the same researchers wanted to know if the biting and chewing behaviors provided additional benefits, or were just a sign of the cat’s exuberance in the throes of pleasure.
Sixteen healthy laboratory cats participated in the study, which involved observing their behavior as samples of intact, crumpled and torn catnip and silver vine leaves and iridoid cocktails in cans of Petri dishes were placed in front of their cages.
The team also conducted a series of other tests on the effectiveness of various plant extracts and iridoid mixtures as mosquito repellents, as well as on the concentrations of volatile compounds surrounding cat-damaged leaves. .
All in all, it was clear that the extra damage from tearing the leaves really helped get the party started a lot faster.
“We found that physical damage of silver vine by cats promoted immediate emission of total iridoids, which was 10 times higher than that of intact leaves,” said lead author Masao Miyazaki, an animal behavior researcher from Iwate University in Japan.
Not only was the total concentration higher in both plant types, but the mixture of iridoids was more complex in the torn silver vine leaves, making it a more potent repellent at lower concentrations.
Cats that were exposed to these mixtures were also affected for a longer duration, suggesting that their biology was “tuned” to maximize the insect repellent doses of the silver vine.
“Nepetalactol makes up over 90% of total iridoids in intact leaves, but this drops to around 45% in damaged leaves because other iridoids increase dramatically,” said Miyazaki.
“The altered iridoid mixture corresponding to the damaged leaves promoted a much more prolonged response in cats.”
The use of natural insecticides stolen from plants and even other arthropods is not unknown in the animal kingdom.
Not only us humans beckoned Chrysanthemum extracted for generations to ward off insects, lemurs have adapted to rubbing millipedes on their bodies as a form of pest control, while other birds and animals have anointed themselves with citrus leaves for similar purposes.
Yet few seem to derive quite the same pleasure from their protective body rubs. These cats seem to be onto something.
This research was published in iScience.
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