“Four minutes is too long.”
Some of Chris Zuo’s itchy results after his session with the mosquitoes.
David L. Hu
That’s the note undergraduate Chris Zuo sent me along with photos of countless mosquito bites on his bare skin. This full-body massacre wasn’t the result of a camping trip gone awry. He’d spent that limited amount of time in a room with 100 hungry mosquitoes while wearing nothing but a mesh suit we thought would have protected him.
Thus began our three-year journey trying to understand the behavior of a deceivingly simple insect, the mosquito. It may sound like a professor’s sadistic plan, but, really, we did everything by the book. Our university’s institutional review board approved our procedures, making sure Chris was safe and not coerced in any way. The mosquitoes were disease-free and native to our home state of Georgia. And this session resulted in the first and last bites anyone received during the study.
Besides my role as torturer of students, I am an author and professor at Georgia Tech with over 20 years of experience studying the movement of animals.
Mosquitoes are the world’s most dangerous animal. The diseases they carry, from malaria to dengue, cause over 700,000 deaths per year. More people have died from mosquitoes than wars.
The world spends US$22 billion per year on billions of liters of insecticides, millions of pounds of larvicides, and millions of insecticide-treated bed nets – all to fight a tiny insect that weighs 10 times less than a grain of rice and has only 200,000 neurons.
Yet, people are losing the war on mosquitoes. These insects are evolving to thrive in cities and spreading disease more rapidly with climate change. How can such simple animals find us so easily?
Scientists know mosquitoes have terrible eyesight and depend on chemical cues to make up for it. Knowing what attracts a mosquito, though, isn’t enough to predict its behavior. You can know a heat-seeking missile is drawn to heat, but you still won’t know how a missile works.
Enter Chris and his self-sacrifice in the mosquito room. By tracking the flight of many mosquitoes around him, we hoped to determine how they made decisions in response to his presence. Understanding how mosquitoes respond to humans is a first step to controlling them.
How mosquitoes zero in on their meal
Out of 3,500 species of mosquitoes, over 100 species are classified as anthropophilic, meaning they prefer humans for lunch. Certain species of mosquitoes will find the one person among a whole herd of cattle in order to suck human blood.
This is quite a feat considering mosquitoes are weak flyers. They stop flying in a slight 2-3 mph breeze, the same air speed generated by a horse’s swinging tail. In calmer conditions, mosquitoes use their minuscule brains to follow human heat, moisture and odors that are carried downwind.
Carbon dioxide, the byproduct of respiration of all living…
