The experiment really shouldn’t have worked. Several years ago, Laura Duvall from Rockefeller University decided to feed mosquitoes with experimental drugs designed to suppress the appetite of humans. Perhaps these chemicals might also reduce the insects’ appetite for blood? And, by extension, stop them from biting people and spreading diseases?
“The whole thing started off as a joke,” says Leslie Vosshall, who led the study. “The assumption was that the human drugs would kill the animal or have no effect. It was a stupid thing.”
So imagine her surprise when it worked.
The Aedes aegypti mosquito, which spreads dengue and Zika, is an exceptional human hunter, drawn to our body heat, odors, and exhalations. When a female finds and bites a person, she doubles her body weight in blood, before lapsing into a days-long food coma. During that time, while she slowly digests the blood and converts it into eggs, “her interest in human cues is dialed down to zero,” Vosshall says. “You can put your hand in a cage of blood-fed females and you won’t get a bite.”
That switch between relentless hunter and disinterested layabout is so stark that about a decade ago, Vosshall started wondering if she could control it. She focused on a small protein called neuropeptide Y, or NPY. Among its many roles, it acts as a universal appetite controller, influencing feelings of hunger across the animal kingdom. Its exact effect varies among species: It drives flies and humans to eat but, as Duvall found, it does the opposite in mosquitoes, suppressing their appetite.