Mosquitoes Can Remember People Who Swat at Them

Researchers from the University of Washington have discovered that mosquitoes can remember and avoid people who swat at them, according to a recent study in the journal Current Biology.

Scientists have long known that mosquitos are able to remember how people smell, which is how they develop preference for certain individuals. However, the new findings show that mosquitoes can change that preferences when someone they feed on tries to hit or harm them.

The team in the study tested this by training female Aedes aegypti mosquitoes to associate certain odors with harmful shocks or vibrations. After leaving the bugs in a chamber for 24 hours, the team found that almost all of the animals stayed away from odors that came with unpleasant feelings.

To explain that behavior, the researchers fitted the insects with small helmets that revealed dopamine — which is behind the reward and pleasure centers of the human brain — is behind the process. The substance controls the area of the brain where olfactory information is processed and makes it easier for mosquitoes to tell the difference between hosts.

This finding is important because Aedes aegypti mosquitoes carry a range of diseases, including dengue fever, yellow fever, and Zika. A better understanding the way they target and feed could have implications for control practices. 

“Once mosquitoes learned odors in an aversive manner, those odors caused aversive responses on the same order as responses to DEET, which is one of the most effective mosquito repellents,” said study co-author Jeff Riffell, a researcher at University of Washington, in a statement. “By understanding how mosquitoes are making decisions on whom to bite, and how learning influences those behaviors, we can better understand the genes and neuronal bases of the behaviors.”