Research published this week in iScience highlights the unexpected benefits of catnip and silver vine, both of which can act as natural mosquito repellents. The study, conducted by researchers at the University of Iwate in Japan, explores the behaviors of cats when interacting with these plants and the chemical changes that occur when the leaves are damaged.
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Cats are known for their euphoric response to catnip and silver vine, often seen chewing, licking, rolling, and rubbing against them. Masao Miyazaki, an animal behaviorist involved in the study, noted that these behaviors help cats transfer chemical compounds, particularly iridoids, which not only stimulate endorphin release but also repel mosquitoes.
The researchers analyzed both intact and chewed silver vine leaves, as well as leaves crumpled by hand. They discovered that damage, whether from cats or humans, resulted in an increase in the emission of iridoids. This chemical enhancement was not uniform; damaged leaves presented a more complex mixture of chemicals that proved to be more effective at repelling mosquitoes and eliciting feline interest. Cats showed a preference for the more balanced chemical profile of damaged silver vine over intact leaves.
In contrast, catnip reacted differently to damage. While it increased emissions of the iridoid compound nepetalactone when damaged, it did not diversify its chemical profile like silver vine did. Despite this, crumpled catnip leaves were still appealing to cats and effective against mosquitoes, although in larger quantities compared to silver vine.
Benjamin Lichman, a plant biochemist not involved in the study, emphasized that this research underscores the significance of chemical mixtures rather than single compounds in animal interactions.
The evolutionary origins of this behavior in domestic cats remain uncertain. However, similar behaviors have been observed in larger felines, indicating a potentially shared ancestral trait.
Given the mosquito species studied spreads diseases to both pets and humans, the findings suggest that catnip and silver vine could lead to safer, more effective insect repellents for human use. However, Miyazaki cautioned that these compounds may inadvertently attract cats, which could be a consideration for those allergic to or not fond of felines.