A team of researchers is employing drones to disperse sterile mosquitoes to combat lethal disease outbreaks such as dengue fever.

The team at BirdView, a startup based in São Paulo, Brazil, has been working for years on controlling mosquitoes in crops using aerial methods. But when the team was introduced to the possibility of controlling crop pests and vector-borne diseases like dengue, they got to work. 

"We immediately saw the impact of potentially using our technology and our systems to help alleviate some of the damage," Ricardo Machado, an environmental engineer and co-founder of BirdView, told Tech Times in an interview.

The drone-based system for aerially releasing mosquitoes has been shown to drastically reduce mosquito populations, which could potentially reduce the spread of diseases like dengue, Machado said. Aerial release of sterile mosquitoes is a common pest control strategy worldwide. The approach involves mass breeding and sterilization of target pests using radiation, followed by aerial release of sterile males over defined areas. These sterile males mate with wild females, and because females of the target species reproduce only once in their lifetime, the strategy results in no offspring and a decline in the pest population.

One of the insects Machado and his team focus on is Aedes aegypti, a known carrier of several viruses, including yellow fever, dengue, and Zika. Dengue, in particular, has become a growing concern, especially in the Americas. According to the World Health Organization, 2023 recorded the highest number of dengue cases in the region, with well over four million cases and more than 2,000 deaths. This trend has continued into 2024, with more than 600,00 cases reported in early February, a staggering 157% increase over the same period last year.

Regarding the impact the system could have on reducing A. aegypti mosquito populations, Machado explains that he and his team are actively working with insectaries to scale up their current system to the city level, where dengue is becoming more of a problem. The drone-based system is designed to transport and release the insects comfortably. This is important to ensure that the released sterile mosquitoes are not in a stressed state and are thus able to compete with wild mosquitoes and mate with females. 

BirdView's system consists of two main components: a release unit attached to drones and a packaging unit to transport the insects. A drone flies over an urban area and can release up to 17,000 sterile insects. 

Although A. aegypti has been the focus of the BirdView team, the cartridges can also hold other insect species, helping to release other mosquitoes in fields. "Our system is also compatible with a wide number of beneficial insects, [...] so it can be a bit more flexible for the operator who can use the same equipment for agriculture and forest restorations," Machado explains.

Typically, sterile mosquitoes can be released in several ways, including terrestrial and drone release. Machado's team compared the two methods and found that aerial delivery can produce faster results. 

In a field trial, they compared two neighborhoods, one treated by car and the other by drone release. Both methods reduced mosquito populations by about 90%, but the drone did it in about three to four weeks, while the terrestrial release method did it in two months. "In a car, you have to follow the roads and the roads typically go around city blocks, so you are releasing the insects along the perimeter of the city blocks. Whereas, with the drone you are releasing it homogeneously regularly within city blocks as well. So you get a much more homogeneous release, and this increases the probability that the sterile male will find wild females to mate," Machado explains.

But despite the differences, the engineer adds that having both systems in place is important. "We have to remember that these are not competitive methods. In the end, I imagine all systems will be used in a complimentary way," he adds.

Jérémy Bouyer of the French Agricultural Research and Cooperation Organization worked with the aerial release of sterile mosquitoes and had the opportunity to work with a BirdView prototype.

 "We did some lab trials [at the International Atomic Energy Agency], and the system was quite good," he told Tech Times in an interview.

However, Bouyer argues that it would be useful to look at published results on how successful the sterile mosquitoes released by BirdView are at mating with females compared to wild males.

Machado says he and his team are working on publishing results on this topic soon. In the meantime, they're focused on partnering with more and more farmers and city managers to get their drone-based system where it's needed. "This is something that we're trying to bring to market and essentially make available whenever and wherever people want it," Machado said. 

About the author: Bárbara Pinho is a freelance science journalist. Her work work has appeared in New Scientist, Chemistry World, Discover, Chemistry & Industry News, National Geographic. Her website is https://www.barbarapinho.com/