Mosquitoes learn not to mess with you when you swat them

The jarring vibrations of a slap may be enough to put the mosquito off your alluring aroma, even if your efforts didn’t manage to mash the insect to a bloody pulp.

To test how well these pesky bugs can remember a turbulent experience—and the scent associated with that—researchers put insects through tests involving tiny flight simulators, mini wind tunnels, and the odor of humans, rats, and chickens. Their results, published in this week’s Current Biology, found that mosquitoes were capable of remembering defensive individuals for at least a day, and avoiding them like the plague, (or, in their case, avoiding them like DEET).

The researchers looked at Aedes aegypti aegypti mosquitoes, a species that evolved to like us. Like, like like us.

“The entire mosquito has evolved to identify us and to bite us. They are especially sensitive to temperature, to the water vapor from our sweat, to our body odor, and to the carbon dioxide from our breath, so their entire sensory systems are geared towards locating us,” says Jeffery Riffell, lead author of the paper.

If kept from their preferred food choice, these mosquitoes will make do with blood from cattle or dogs to sustain themselves. But that’s only if they have to. In other experiments, Riffell says, researchers showed that even mosquitoes that only had access to dogs or cattle for most of their adult lives would gravitate back to humans if given the chance.

“Their ability to shift hosts hasn’t lost that innate preference for humans. And so we think learning is causing that shift and that flexibility,” Riffell says. He and his colleagues wanted to look into what drove the preferences for hosts, and if mosquitoes might learn to avoid certain humans that proved too challenging.

“We all have our own scent signature—a fingerprint, if you will,” Riffell says. “And this fingerprint is stable, it doesn’t change very much over the course of weeks or months. Mosquitoes, once they are actually biting you, they are smelling you. If you try to move your arm to shake them off or try to swat them, they will feel the vibrations of the swat and learn a negative association between those vibrations and your scent. Given that we each have our own scent fingerprint, we found that they can actually remember certain individuals.”

“They avoided certain odors as strongly as if they were experiencing 40-percent DEET,” Riffell says. “They can really remember the odor, and it can cause a high degree of repellency in them.”

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