Mosquitos can remember the smell of a person that has swatted them and use it to avoid them in the future, new research has found31617-2).
"When encountering a defensive host, mosquitoes are exposed to mechanical perturbations (e.g. swatting, shivering) that can be perceived as negative reinforcement by the insect when paired with other host-related cues such as host odours," the paper read.
The article, published in Current Biology, also found that Aedes aegypti mosquitos' entire sensory systems are geared towards locating humans.
Mosquitos of this kind make do with blood from cattle or dogs to sustain themselves but only if there is no human blood on offer.
“The entire mosquito has evolved to identify us and to bite us. They are especially sensitive to temperature, to the water vapour from our sweat, to our body odour, and to the carbon dioxide from our breath,” Jeffery Riffell, lead author of the paper told Popular Science.
To gather results researchers at the University of Washington, Seattle, trained female insects inside small individual chambers in which they had to fly upwind and choose between two arms, one with the odour of a human they had already been swatted by and the other a control odour that they had not experienced.
"Naive" mosquitos (insects that had not been in contact with humans) "strongly preferred" human scents to any other, whereas "trained" bugs (creatures that had previously been struck) actively avoided the arm with this odour.
The trained insects were capable of remembering defensive individuals for at least a day.
Results also found that some human subjects were more appealing to mosquitoes than others and the insects remembered these individuals better than others.
Dopamine was critical to the bugs' ability to learn, enabling them to remember positive and negative associations—like what swatted them, for example.
Researchers are continuing their studies into mosquitos to try and define which of 300 different smells are most attractive to the insects.
They are also looking to find out if a bad experience with one human could mean that the mosquito is put off the whole species.
This research only tested the creature's memories over 24 hours but scientists hope to further study them over a longer period of time, as mosquitos can live for a month.