Catnip and silver vine leaves are known to strip up excited fits of rolling around, kicking, and chewing in felines. So much so that even the most indifferent of cats will go crazy after a munching on a few catnip leaves. Most recently, scientists put to rest the age-old question of whether cats respond this way to catnip out of pure pleasure or benefit. A new study on Catnip shows it protects cats from insects. The research, which was published in iScience, suggests that catnip and silver vine leaves produce high levels of chemical compounds that repel mosquitoes and other insects. Let’s review the findings.
Natural Bug Spray
University of Iwate researchers have been studying how cats interact with silver vine and catnip for several years. This team from Japan is behind the research that shows that these plants behave like a natural insect repellent spay and become more effective when chewed or rubbed onto the body. According to the lead author of the study, Masao Miyazaki, cats have a varied natural response to these plants, which includes rolling, rubbing, chewing, and licking. As reported by the Smithsonianmag, these behaviors are crucial to the effectiveness of catnip and silver vine as natural bug sprays. Miyazaki confirms that rolling and rubbing are crucial to transferring iridoids to cat fur and promoting mosquito repellence. Iridoids are chemicals that trigger the endorphin rush in feline animals. However, the research did not explain the reason for the other two reactions to catnip and silver vine – chewing and licking.
To conduct the study, the team of researchers examined closely the results of cats damaging catnip and silver vine leaves on a chemical level. They began by collecting intact silver vine leaves, others that they crumpled up by hand, and others that had been chewed up by cats. Running a chemical analysis on the three groups showed that the damage caused by humans and cats led to an increase in iridoid emission. A closer look at the damaged leaves also revealed that they contained an even balance of five chemicals and were not dominated by a single component. The team then exposed the different groups of leaves to cats and mosquitoes to observe their reactions. When presented with both damaged and intact silver vine leaves, cats spent more time rolling around and licking the former. Synthesizing the chemical components found in these leaves led to the same results – the cats were more attracted to the cocktail made from the damaged leaves.
Before this, scientists believed that a chemical called nepetalactol was responsible for attracting cats to silver vine. However, the findings from this new study show that the effect is caused and heightened by the cocktail of several chemicals present in damaged leaves. Cats preferred the well-balanced iridoid mixture in these leaves to the simple one found in intact leaves. Reiko Uenoyama, an Iwate University graduate student and lead author of the study said that she was “…really surprised that the combination of iridoid compounds enhanced the feline response.” The study also found that the chemical cocktail cats found more attractive was also more repellent to mosquitoes. The researchers filled a clear box with mosquitoes and introduced a shallow dish of silver vine mixture into it. When the varied cocktail from damaged leaves was introduced, the mosquitoes dispersed faster than when the simple, intact-leaf cocktail was added.
Silver Vine Vs. Catnip
Although damaging silver vine leaves diversified their chemical profile, the effect was not observed in catnip. Catnip’s primary iridoid component is nepetalactone and not nepetalactol. While the emissions do increase upon cat damage, the chemical released is still only nepetalactone. That said, crumpling up either of these leaves still made it more attractive to cats and more repellent to mosquitoes. When compared to each other, the researchers found that a larger catnip cocktail dose was required to trigger the same reaction from cats and insects as a very small dose of silver vine. However, catnip emitted more chemicals overall than silver vine leaves. The effect is that cats find both leaves equally attractive despite the slight chemical composition differences.
Scientists are still unsure about why even small amounts of these complex chemical mixtures can trigger strong responses in cats and mosquitoes. But despite these unanswered questions, many are happy with the research because it sheds light on the effectiveness of chemical mixtures in animals compared to simple, single compounds. The study also raised questions about when cats first developed their reaction to catnip and silver vine. Previous studies have found that jaguars and leopards also cover themselves on nepetalactol so this behavior may have been passed down from a distant feline ancestor.
Researchers are already thinking about how these findings can be applied to human lives. It is possible that silver vine and catnip can be used to protect human beings from mosquitos. Although the mosquito species used in this study transmits roundworms to dogs and cats, ecologists believe it could be applied successfully to other species too. A chemical ecologist from Lund University called Nadia Melo previously conducted research that suggests this. Melo says, “I think all mosquitoes would react pretty much the same way.” She also believes that chemicals produced from silver vine and catnip could make effective mosquito repellants for human use. However, she cautions that the chemical mixtures could also attract cats, which could be inhibiting to people with cat allergies or who do not like cats.
Many cat owners are familiar with catnip as a feline treat that cats love to chew and roll in, but new study on Catnip shows it protects cats from insects. According to the research, cats are able to release more insect-repellant chemical compounds from catnip and silver vine by rubbing themselves against the leaves. This action then protects them from insects such as mosquitoes. The lead author of the stud, Masao Miyazaki, released a press release saying, “We found that physical damage of silver vine by cats promoted the immediate emission of total iridoids, which was 10-fold higher than from intact leaves.”