Mosquitoes are way smarter than previously thought. Findings of a new study have revealed that swatting them away actually teaches them to stay away from a host.
Mosquitoes Can Learn And Remember Smells
In a new study published in their journal Current Biology on Jan. 25, researchers showed that mosquitoes can learn and remember the smells of their hosts, allowing these pesky pests to develop preference for certain individuals. This preference, however, may shift if the smell of this individual is associated with an unpleasant sensation.
University of Washington researchers trained female Aedes aegypti mosquitoes to associate odors with unpleasant shocks and vibrations. The mechanical shocks employed used a vortex mixer to simulate the vibrations and accelerations that mosquitoes experience when a person tries to swat them.
After 24 hours, the researchers observed that the mosquitoes abandon most of the hosts associated with swatting or performing other defensive behaviors, which suggests the mosquitoes have been successfully trained.
The researchers were also able to pinpoint dopamine as a key mediator of the process. In humans, dopamine helps control the reward and pleasure centers of the brain.
The researchers fitted the mosquitoes with a helmet so they can observe the reactions of the insects when exposed to various smells, including human body odors. They found that dopamine modulated the neural activity in the brain region where olfactory information is processed to make it easier for mosquitoes to potentially learn and discriminate hosts.
"We show that olfactory learning may contribute to Aedes aegypti mosquito biting preferences and host shifts. Training and testing to scents of humans and other host species showed that mosquitoes can aversively learn the scent of specific humans and single odorants and learn to avoid the scent of rats (but not chickens)," the researchers wrote in their study.
Implications On Fight Against Mosquito-Borne Diseases
Aedes aegypti mosquitoes are carriers of dangerous viruses that cause dengue fever, Zika, chikungunya, and yellow fever. Researchers said that understanding how mosquitoes target hosts may have implications on mosquito control.
"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 researcher Jeff Riffell, from UW.
"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."