Drones Distribute Swarms of Sterile Mosquitoes to Stop Zika and Other Diseases

Keeping a million mosquitoes alive on board a drone isn’t as easy as you think

Advertisement

The deadliest animal on Earth, by far, is the mosquito. Each year, mosquitoes infect about 700 million people with diseases such as malaria, dengue fever, West Nile virus, and Zika. Millions of people die annually from mosquito-borne illnesses, and many of those diseases can’t be cured with drugs. It’s best to avoid being bitten in the first place, but this is becoming more difficult as the insects expand their range, migrating north with warming climates.

For decades, government agencies and nonprofit organizations have tried to prevent the spread of mosquito-borne diseases in developing countries by spraying large areas with insecticides. But that process is expensive, especially as mosquitoes develop resistance to commonly used chemicals. The United States Agency for International Development (USAID) has begun to look for other mosquito control methods.

One approach is to breed male mosquitoes in captivity, expose them to radiation that renders them sterile, and release them into the wild. These mosquitoes, being mosquitoes, don’t understand that they can no longer successfully reproduce, and do their best to make it happen anyway. In large enough numbers, the sterile males will outcompete wild males for female mosquitoes, which can reduce local populations by as much as 90 percent.

This method has been around for half a century, but spreading sterile mosquitoes in the developing world is a challenge. Roads are nonexistent or in poor condition, so it may not be possible to release insects from a car or truck, and using a crewed aircraft is too expensive.

In 2016, USAID funded an organization called WeRobotics, which has dual headquarters in Washington, D.C. and Geneva, Switzerland, to engineer a system that can deploy sterile mosquitoes from autonomous drones instead. USAID and WeRobotics want to see whether drones can replace conventional aircraft as a way to manage mosquito populations over hundreds of square kilometers. “We hope to greatly increase the area that we can cover by using drones,” says WeRobotics’ cofounder Adam Klaptocz.

Klaptocz and his colleagues started WeRobotics to explore ways that drones can have a positive social impact. Over the past few years, they’ve set up community robotics labs in developing nations around the world. WeRobotics and its partners have used drones to map roads in Nepal, deliver medicine in Peru, and coordinate humanitarian efforts in the Caribbean after Hurricane Maria.

The company’s latest project is testing a prototype drone-based mosquito control system in South America. The challenge here is not the drone itself—it’s how you carry and release mosquitoes from that drone. “Mosquitoes are very fragile animals,” Klaptocz explains. “If you put hundreds of thousands of them into a very small box, they’re going to damage themselves, and damaged mosquitoes will not be able to compete with wild mosquitoes.”

The goal is to pack as many mosquitoes as possible into the drone. However, clumping is a problem because the insects form “a big collection of legs and wings,” he says. The trick, according to Klaptocz, is to keep them inside a precooled container: “Between 4 °C and 8 °C, they’ll fall asleep, and you can pack them up fairly densely.”

It’s also important to control the release of the mosquitoes, rather than dumping them out all at once. “We tried different systems to get the mosquitoes out of the holding canister, including vibrations and a treadmill,” he says. “Right now, we’re using a rotating element with holes through which individual mosquitoes can fall.” Once the mosquitoes fall out of the canister, they spend a few seconds in a secondary chamber warming up to the outside air temperature before exiting the drone, to make sure they’re awake and ready to fly.

It’s not yet clear that drones will be much more effective than humans with backpacks at dispersing mosquitoes, says Robert Malkin, an expert on new health-care technologies at Duke University. And sustaining any kind of operation in remote areas with little infrastructure will be a challenge. “But it could work,” he says. “It sounds like a cool project.”

WeRobotics will conduct its first experiments for USAID with sterilized male mosquitoes in late 2017 or early 2018, somewhere in South or Central America. “Our next step is running controlled tests, where we mark the insects, release them, and recapture them in traps to measure whether they’re healthy or not,” says Klaptocz.

WeRobotics’ deployment system works with different kinds of mosquitoes and any model of drone. For future projects, it could carry and release male mosquitoes that have been genetically modified to have sterile offspring; male mosquitoes that have been infected with a bacteria called Wolbachia pipientis, which makes their offspring sterile; or female Wolbachia-infected mosquitoes, which are less likely to transmit diseases when they bite.

But before they begin any live mosquito testing, WeRobotics must work with local communities to win their support. “We’re trying to control disease vectors,” Klaptocz explains. “But practically, what we’re doing is releasing a whole bunch of mosquitoes into communities and flying drones over them. Engagement with these communities has to be done from the beginning, by talking to people and involving them in the process.”

A version of this article appears in the December 2017 print magazine as “Drones Make a Special Delivery—Mosquitoes.”

Advertisement