Fight against mosquitoes: robots sort insects, drones release them

Even in 2024, diseases transmitted by mosquitoes have not been eradicated – on the contrary, they are even spreading to new regions. People tend to forget that malaria, for example, once also existed in Europe. Global warming and the unwanted import of insect species from the south are doing the rest. It would be good to take faster and more targeted action against mosquitoes. Two research groups have now proposed technologies that could help: they are relying both on innovative robotic systems for sorting the animals and on unmanned aerial vehicles, i.e. drones.

Robot selects suitable animals

It was shown decades ago that one of the most promising methods of preventing the transmission of diseases by insects is direct intervention in populations. This does not involve trying to eradicate mosquitoes completely –, which is difficult to do. Instead, changes are introduced into the animals, for example by treating them so that they cannot reproduce or by using bacteria to combat the parasites or viruses they carry.

In most cases, however, the right animals have to be found first: Depending on the control method, these must be male or female animals. However, sorting using current techniques, which is sometimes still done by hand, is extremely laborious.

A Chinese research team led by Jun-Tao Gong from Guangzhou Wolbaki Biotech and colleagues led by Wadaka Mamai at the IAEA Center of Nuclear Techniques in Food and Agriculture in Vienna have now developed a robotic doll sorter. The system is almost completely automated and has already been tested with three mosquito species. It is said to be up to 17 times faster than current processes and can process millions of animals per day.

If the current prototype can be scaled up, it is conceivable that a single person operating several machines simultaneously could produce up to 16 million animals of one sex per day – with a very low miss rate of 0.5 percent. According to the researchers, this could overcome a "long-standing bottleneck" in the production of sterile mosquitoes. Most of the mosquitoes would have survived the sorting process unscathed. A successful field test has already been completed in China, which helped to suppress a natural population.

Out with the mosquitoes

But what to do with the modified animals, and what is the best way to get them to the target area? A team led by Ya-Hsun Lin and colleagues as part of the World Mosquito Program, which is managed from Australia, has now developed a new type of application system that relies on drones. These could work with significantly less loss than previous release technologies, which work from an airplane, for example. The fact that the technology works has been demonstrated in two field trials to combat dengue fever in Fiji. 160,000 mosquitoes can be released per load, even in remote locations. The animals of the species Aedes aegypti were previously treated with the bacterium Wolbachia in such a way that the dengue virus is blocked in them.

Female mosquitoes pass Wolbachia on to their offspring. For them to do the same to their brothers and sisters in the natural population, they must first be brought there. In jungle regions or areas of a country that cannot be reached by road or sea, this can be difficult. Lin and Co's system is designed to keep the animals alive for as long as possible using an integrated temperature and humidity system. They are then flown to their destination. There, 150 animals per "dose" can then be released.

The system was able to establish a successful population in an area of two square kilometers on Fiji. "Innovations and new technologies such as this aerial release device are critical to improving capabilities and capacity in our integrated fight to contain dengue transmission worldwide," commented mosquito researcher Jacob Crawford in the Science Robotics journal that published Lin's paper. The system could also be used against other mosquito-borne diseases, the researchers say. These include Zika and Chikungunya fever, which are also spread by Aedes aegypti.

(mack)