The Plan to Drop Thousands of Flies From a Drone to Tackle Disease

This drone prototype will carry precious cargo: an army of insects engineered to wipe out their own kind.

A drone about to drop something is typically a cue for widespread destruction. But that's not the case with this F300 fixed-wing and its unusual cargo: Instead of unleashing catastrophe, the automated machine is designed to do good—by releasing a swarm of tsetse flies.

This may seem peculiar at first, especially given the tsetse fly's reputation. This African insect harbours harmful parasites called trypanosomes, spreading them to humans and animals through its bite. In humans, the resulting disease, trypanosomiasis, causes "sleeping sickness," a potentially fatal condition that attacks the central nervous system and, as the name suggests, afflicts people with an uncontrollable urge to sleep. In livestock, it brings on "nagana," which causes muscle wasting, paralysis, and eventual death. Losing cattle, particularly, has knock-on effects for agriculture and food security.

Now Spanish drone company Embention is part of an unlikely solution in Ethiopia, where the disease ravages livestock: eradicating trypanosomosis using the very culprits responsible for its spread. To do it, the heroically-titled project Drones Against Tsetse combines drone technology with a biological control method known as the Sterile Insect Technique (SIT).

The Embention team with the drone during trials in Spain. Image: Embention

SIT works by exposing male insects to radiation, which sterilises them and thus destroys their ability to breed. It's garnered attention in recent years as a possible tool for controlling the spread of malaria via mosquitoes; now in Ethiopia it's being applied to hundreds of thousands of male tsetse flies reared at facilities in Addis Ababa, where the project's research headquarters lie.

The work is supported by the Ethiopian Ministry of Livestock, the United Nations Food and Agricultural Organisation, and the International Atomic Energy Agency, an organisation that promotes the peaceful use of nuclear technologies in scientific research and is pioneering SIT research in many countries. The researchers have so far shown that when released into the wild, the radiated tsetse males fail to breed with females, effectively erasing the next generation and undermining the population. That leaves fewer tsetse flies around to infect humans and animals.

Embention's drone prototype—so far trialled in Spain and awaiting approval for use in Ethiopia—comes in as a way to seed the wild populations with their sterilised brethren.

The drone during testing in Spain. Image: Embention

The radiated flies will be loaded into boxes enclosed within long chambers that sit below the drone's wings, explains Javier Espuch, one member of the five-strong team who developed the drone. Flying autonomously, the machine follows pre-set coordinates that pinpoint areas known to be infested with the insects: "When the drone reaches that area it automatically drops the flies," says Espuch. The biodegradable, open-sided boxes free the insects as they fall.

Boxes can be released from the wing pod at pre-arranged intervals, to control and maximise the spread of radiated insects according to each location. "Release rates can be adjusted for conditions in specific areas, something that is useful in areas with complicated topography," said Rafael Argiles-Herrero, an entomologist at the IAEA. By repeatedly dropping non-breeders into the midst of wild swarms, the drone will gradually weaken localised populations of tsetse flies.

For humans, the risk of contracting trypanosomiasis is declining in many countries. But in places like Ethiopia where livestock feel the brunt of its impact, disease-ridden animals can drastically undermine agricultural production because farmers rely on cattle to till the land. Agriculture accounts for 43 percent of Ethiopia's GDP and provides 85 percent of its employment, so it's a risk worth fighting.

A tsetse fly from Burkina Faso. Image: IAEA/Wikipedia

"Some 200,000 km2 of lower-lying, fertile and well rain-fed land remains under used because of tsetse infestation," Argiles-Herrero said. These tsetse-swarmed areas will be the drone's target.

Until now, the project has relied on people to manually drop the fly boxes from an airplane over Ethiopia's Deme River Basin, a 1,000-km2 tsetse fly hotspot. But the drone will make this process cheaper, safer, and—since it flies just 300 metres above ground—more precise, said Espuch. "To be effective, they need to fly every day, so the cost involved in it decreases a lot, because you don't really need a trained pilot for this," he said.

The drone can also rapidly expand the release program into other tsetse-infested environments: Argiles-Herrero sees its potential in another 24,000-km2 expanse of Ethiopia's Southern Rift Valley.

When the prototype receives approval and hopefully reaches Ethiopian skies in coming months, it will be capable of raining down 5,000 insects per flight. As for the tsetse flies, they might not be its only passengers: "The same release system can be used for sterile mosquitoes," notes Argiles-Herrero. If all goes well, malaria could be the drone's next frontier.