Summer weather is heating up, and more people are headed outdoors to enjoy nature. But as climate change continues to drive temperatures higher, the natural ranges where ticks can thrive are expanding further north.
That’s bad news for Canadians because tick-borne diseases like Lyme disease can be serious.
Gerhard Gries, professor of biological sciences at Simon Fraser University, led a study that found a new bio-inspired way to keep blacklegged ticks from getting close to hikers and campers with synthetic ant pheromones. Their study was published in Royal Society Open Science.
Ticks and ants both spend much of their lives in leaf litter and other debris on the ground to shade themselves from the sun. Ants are among the leading predators for ticks, so avoiding ants can help ticks survive.
“We decided to look at ants because they are social insects and use a huge range of pheromones to communicate with one another,” said lead author Claire Gooding in a press release.
“They’re chemically noisy. And for something that perceives the world chemically, they’re easy to predict where they’ll be, based on these pheromones.”
The team found that a mix of pheromones from the ants’ poison glands and Dufour’s glands acted as a natural tick repellent. Ants use these pheromones as chemical messengers to communicate with each other, but the ticks are able to ‘eavesdrop’ on the messages to know where ants have been so they can avoid the places they are likely to return to at some point.
The study used a set of three connected chambers to identify the right mix. At the beginning of each trial, a tick is placed in the middle chamber, connected by tubes to two other chambers, one containing a cotton ball wetted with potential repellents, and the other a cotton ball wetted with water to maintain similar humidity. After allowing the tick to move freely for 20 hours, they looked to see whether they ended up in one of the side chambers; any found in the central chamber were considered non-responders.
Ticks avoided the test chambers with the mixture of compounds from the ants’ poison glands and Dufour’s glands and migrated to the water chamber. They were able to replicate the same effect with a synthetic version of the mixture.
In the study, the ticks were only exposed to the potential repellents, and the real world would have many more cues, like the scent of deer or hikers who could be a source of their next blood meal.
The team hopes that with more development that this approach might be used on the skin or on clothing, similar to mosquito repellents. Another option is to apply synthetic pheromones to items like wood chips to form a physical barrier that keeps ticks away from places like camping areas or hiking trails.
This bio-inspired approach to preventing tick-borne diseases could help protect our health while we enjoy the great outdoors.
