Mosquitoes Avoid Defensive Hosts
Nobody likes mosquitoes for their stinging bites and nuisance nature. But for those who receive more bug bites because they are deemed delicious-smelling, researchers know how to be more defensive. How? Pioneering research scientists from Virginia Tech discovered that although mosquitoes remember the smells of hosts, the insects avoid those that were more defensive.
According to the study, mosquitoes can rapidly learn and remember the smells of hosts. The researchers learned that this amazing nature of the insects is due t dopamine which serves as mediator of this process. Mosquitoes use this information and incorporate it with other stimuli to develop preferences for a particular vertebrate host species, and, within that population, certain individuals.
Interestingly, swatting mosquitoes can be the best way to avoid the bug because these insects exhibit a trait known as aversive learning. Hosts who swat at mosquitoes or perform other defensive behaviors may be abandoned, no matter how sweet.
These key findings were confirmed by Chloé Lahondère, a research assistant professor in the Department of Biochemistry.
Lahondère said, “Unfortunately, there is no way of knowing exactly what attracts a mosquito to a particular human – individuals are made up of unique molecular cocktails that include combinations of more than 400 chemicals. However, we now know that mosquitoes are able to learn odors emitted by their host and avoid those that were more defensive.”
The study was also co-authored by Clément Vinauger, an assistant professor of biochemistry in the College of Agriculture and Life Sciences. Vinauger and Lahondère are both affiliated with the university’s Fralin Life Science Institute, which supports vector-borne disease research as a major thrust area.
The Discovery
The scientists demonstrated that mosquitoes exhibit the aversive learning trait by training female Aedes aegypti mosquitoes to associate odors (including human body odors) with unpleasant shocks and vibrations.
Twenty-four hours later, the same mosquitoes were evaluated in a Y-maze olfactometer in which they had to fly upwind and choose between the once-preferred human body odor and a control odor. The mosquitoes avoided the human body odor, suggesting that they had been successfully trained.
Researchers used an insect flight simulator (pictured here) along with CRISPR gene editing and RNAi techniques to determine that dopamine is a key mediator of aversive learning in mosquitoes.
The key results showed they remembered the smell of the host but tend to avoid those who swat at them.
Vinauger said, “Understanding these mechanisms of mosquito learning and preferences may provide new tools for mosquito control. For example, we could target mosquitoes’ ability to learn and either impair it or exploit it to our advantage.”
