Domestic cats love catnip. The fluffy animals are crazy about the purple flowering plant: they rub their heads on it, throw themselves on it, roll around in it and lick and chew the leaves. In addition to the euphoric effect, this also has a practical reason, researchers led by Masao Miyazaki from the Japanese University of Iwate report in the journal “iScience”: The chewed or crumpled leaves increasingly release certain substances, the iridoids. These spread on the cat’s fur when they come into contact with the plant and help to ward off mosquitoes.
As early as 2021, the team found that iridoids in catnip (Nepeta cataria) and the Japanese ray pen (Actinidia polygama), also called Matabi, not only trigger euphoric states in domestic cats, but can also protect the animals from mosquitoes. For the current study, the experts examined how intact and destroyed leaves differ in the amount and composition of the secreted iridoids and how cats reacted to the leaves.
Catnip and Japanese ray-pistil leaves damaged by the researchers or the cats expelled more iridoids than intact leaves. The team also found an altered composition of the ejected iridoids on torn ray-pen leaves. Here it was also possible to measure those that were not measurable at all or only in very small quantities in intact leaves.
To test whether the cats reacted differently to the damaged leaves than to undamaged ones, the researchers placed the leaves in bowls and closed them with lids with holes in them. The cats licked, chewed, rubbed, or rolled over the lid—this response took longer with the torn leaves. According to the team, this means that more iridoids are transferred to the cats’ fur and the animals are therefore better protected against mosquitoes.