by Lindsay Kay
Photos by Kiley Riffell, Gabriella Wolff
Your grandmother’s insistence that you get more bug bites because you’re “sweeter” may not be that far-fetched, according to pioneering research from Virginia Tech scientists.
The study, published Jan. 25 in Current Biology, demonstrates that mosquitoes can learn and remember the smells of hosts, and points to dopamine as a key mediator of this process. The project also proved that a mosquito’s preference can shift if an odor once deemed delicious-smelling becomes associated with something unpleasant. Hosts who swat the insects or perform other defensive behaviors may be abandoned, no matter how sweet.
A Nose For Details: Chloé Lahondère and Clément Vinauger are new researchers in the Department of Biochemestry. Their labs are located in Engel and Fralin halls, and they are affiliated with the Fralin Life Science Institute.
Brainiac: An image of a mosquito brain highlights the presence of dopamine in regions involved with the sense of smell.
Clément Vinauger, an assistant professor of biochemistry in the College of Agriculture and Life Sciences, and Chloé Lahondère, a research assistant professor in the Department of Biochemistry, found that mosquitoes exhibit a trait known as aversive learning by training female Aedes aegypti mosquitoes to associate specific odors with unpleasant shocks and vibrations.
Twenty-four hours after the initial training, the same mosquitoes were assessed in a Y-maze olfactometer. The insects had to fly upwind and choose between the once-preferred human body odor and a control scent. The mosquitoes avoided the human body odor, suggesting that they had been successfully trained.
The scientists were also able to identify that dopamine is a key mediator of aversive learning in mosquitoes. To target the specific parts of the brain involved in olfactory integration, researchers fit mosquitoes with helmets that allowed for brain activity recordings and observations. Then, the scientists were able to analyze how the insects reacted when exposed to various smells. The findings demonstrated that the neural activity in the brain region where olfactory information is processed was modulated by dopamine in such a way that odors were easier to discriminate, and potentially learn, by the mosquitoes.
“Understanding these mechanisms of mosquito learning and preferences may provide new tools for mosquito control,” said Vinauger.
Taking Flight: Researchers used an insect flight simulator along with CRISPR gene editing and RNAi techniques to determine that dopamine is a key mediator of aversive learning in mosquitoes.
Aedes aegypti mosquitoes are vectors for Zika fever, dengue fever, chikungunya, and yellow fever viruses, and can be found in tropical and subtropical regions throughout the world. Vinauger and Lahondère are both affiliated with the university’s Fralin Life Science Institute, which supports vector-borne disease research as a major focus area.
Lindsay Key is the communications director for the Fralin Life Science Institute.