Using drones to help spread sterile mosquitoes
Human activities and climate change will benefit one group: mosquitoes. With anthropogenic activities, environmental modifications and rising temperatures, mosquitoes are increasing in number and are spreading to new locations, including Europe. As vectors of dengue fever, Zika virus and malaria, the emphasis on the development of new methods to combat the growing numbers of mosquitoes. One promising method is the ‘sterile insect technique’ (SIT), in which sterilised male mosquitoes are released into local populations. As they compete with non-sterile males yet produce no offspring, mosquito numbers begin to dwindle. While early results suggest the technique works, it is still carried out inefficiently. Mosquitoes are released from the ground, mostly from open cages on the back of vehicles. “The sterile insect technique is currently under development against invasive mosquito species, but an aerial release system is one of the bottlenecks in scaling it up,” explains Jérémy Bouyer, research director at the French agricultural research and cooperation organisation CIRAD.
Sterile mosquitoes released from the skies
The MOSQUAREL project, supported by the European Research Council and coordinated by Bouyer, has given the idea an upward boost. The MOSQUAREL team has developed drones able to drop mosquitoes from the air, the first such method to do so. The aim of the project was to create and validate an automatic release system, for drones to be able to deploy sterilised mosquitoes in urban areas. “Aerial release is necessary to obtain homogeneous release of the sterile males upon the target area and maximise their impact,” he adds. During the MOSQUAREL project, the team tested the drones in field trials in France and Réunion, with positive results. “We demonstrated that drone release is possible in urban areas,” remarks Bouyer.
Developing the drones and running trials
The MOSQUAREL team tested a custom-made prototype specifically developed to carry their patented release system. However, field-testing and a market study revealed that using drones adapted from other models was a more rational strategy. This way, they could obtain more information on the reliability of the drone when flying in urban settings. The project ran two trials to test the effective release of sterilised males: one in Saint-Joseph, Réunion, using Aedes aegypti mosquitoes; and another in Prades-le-Lez in southern France, using Aedes albopictus. The drone release system was then integrated into a control trial in Saint-Joseph to assess the impact of drone-boosted SIT on the density of a population of Aedes aegypti, in combination with ground releases. The trials showed that releasing sterile male mosquitoes by air over urban areas doesn’t reduce their quality or impact. The team also implemented several improvements to the release system over the course of the project.
Enhancing the prototypes and continuing research
Bouyer is currently working on a related EIC transition project. Next year, he will submit plans for this in collaboration with several European private companies, including a start-up being created to bring the idea to market. “This project would not have been successful without the collaboration of key partners like the FAO-IAEA Insect Pest Control Laboratory, MAPA technologies, IRD and EID-Méditerranée in Prades-le-Lez,” says Bouyer, “as well as USIO-Tech Saint-Joseph in Réunion to drive the drones!”
MOSQUAREL, drones, mosquitoes, automatic, release, urban, sterile, insect, technique