Could stopping 'zzz's' prevent mosquitoes from spreading disease?

Small in size but mighty with their bothersome bites, mosquitoes are often considered the deadliest animals on Earth. That’s because the World Health Organization estimates 725,000 people die each year from mosquito-borne diseases. Many of these diseases, such as the West Nile virus and yellow fever, have experienced recent resurgences and caused public health crises.

To combat these deadly menaces, a professor in Virginia Tech’s College of Agriculture and Life Sciences is researching a state of relaxation that is integral to both insects and humans alike.

Clément Vinauger, an assistant professor in the Department of Biochemistry, received a two-year $430,000 R21 grant from the National Institutes of Health to research the sleep habits of mosquitoes with the thought that if sleep-deprived humans have trouble functioning, maybe sleep-deprived mosquitoes do too.

Vinauger is collaborating with a team from the University of Cincinnati in this research, the first of its kind to study how sleep deprivation may affect a mosquito’s ability to find human hosts or even stop its ability to spread disease.  

“People are suffering and dying all over the world from these diseases, and with climate change, it’s getting worse,” Vinauger said. “To me, that’s the most obvious demonstration that we need to think outside of the box.”

Shaking the sleep and studying the outcomes

A good or bad night’s sleep can define a person’s day, and the same goes for mosquitoes. In humans, a good night’s rest improves memory, immunity health, energy level, and many other functions that contribute to overall well-being.

Unfortunately, solid sleep is just as helpful to the mission of mosquitoes. The more sleep they get, the more likely they are to buzz, bite, and spread disease. Fortunately, though, sleep-deprived mosquitoes are just as miserable as the sleep-deprived humans they hunt.

Most disease-spreading mosquitoes are found in cities, where people, noise, and sound are most populous. But even amongst the hustle and bustle of city life, mosquitoes, like other insects, find time to sleep. More scientifically, they reach a sleep-like state when they land, rest their limbs, and stay immobile for long periods of time, Vinauger said.

Vinauger’s studies suggest that when these states of sleep are interrupted – mosquitoes are prevented from landing and resting – they show signs of fatigue, similar to humans.

“Let’s say you stay out too late on Saturday night. You feel miserable on Sunday and require more sleep to rebound,” Vinauger said. “Mosquitoes do the same thing when they don’t sleep well. The next day, they are very bad at making decisions.”

Important decisions like when and where to find a human host.

The research grant awarded by the National Institutes of Health to Vinauger and grant co-principal investigator Joshua Benoit of the University of Cincinnati will expand upon these studies with two objectives: to characterize what goes on inside mosquitoes’ brains when they sleep and to define the consequences when they are deprived of it.

Vinauger has recruited Shajaesza Diggs, a master’s student, and Nicole Wynne, a Ph.D. candidate, to assist him inside his laboratory in Steger Hall.

“We have a nice preparation in the lab here at Virginia Tech where we can record the electrical activity of neurons in the brains of mosquitoes while they sleep, so we can evaluate how sleep is impacting the way their brain functions,” he said. “We are also going to sleep-deprive the mosquitoes and test their ability to transmit viruses and see how that impacts them.”

To keep the mosquitoes awake in the lab, Benoit and his research team developed a programmable system that vibrates the containers in which the mosquitoes are enclosed. The vibrations are introduced at regular intervals, preventing them from falling asleep.

Vinauger is hopeful the research will reveal new ways to manipulate the environments in which mosquitoes thrive – in rural, humid areas of the world such as sub-Saharan Africa or urban, cooler cities such as New York City. Historically, that has been through the use of chemicals, such as insecticides. But with the rise in cases of mosquito-borne diseases, Vinauger said new strategies are necessary.

“If mosquitoes can escape our control strategies, we need to find new control strategies, and that’s where creativity comes into play,” he said. “If we can better understand how sleep is important for mosquitoes and for disease transmission, maybe we can identify targets for sleep-depriving them, or manipulating the molecular basis of their sleep so they are less efficient at finding us. That could be as simple as changing the frequency of lightbulbs in cities. In more rural areas, it could be using a white noise machine. That remains to be discovered or invented, but the first step is to understand, and that is what we are trying to accomplish.”