The International Atomic Energy Agency (IAEA) and its partners have successfully tested releasing sterile mosquitos from drones as part of efforts to use a nuclear technique to supress the insect that spreads Zika and other diseases.
The IAEA, in partnership with the Food and Agriculture Organization of the United Nations (FAO), has worked with the Swiss-American non-profit group WeRobotics for the last year to develop a drone-based mosquito release mechanism for use in the application of the Sterile Insect Technique (SIT) to control insect pests. Testing of the system was carried out in Brazil last month.
SIT, a form of insect birth control, uses radiation to sterilize male mosquitos, which are then released to mate with wild females. As these do not produce any offspring, the insect population declines over time.
“The release mechanism for mosquitos has until now been a bottleneck in the application of SIT to control human diseases,” said Jeremy Bouyer, medical entomologist at the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture. “The use of drones is a breakthrough, and paves the way for large-scale and cost-efficient releases, also over densely populated areas.”
The technique requires the uniform release of large numbers of insects in good condition over a given area. Aedes mosquitos, responsible for the spread of diseases, do not disperse for more than 100 meters in their lifetime, creating a challenge for the effective application of SIT over large areas. They are also fragile, and high-altitude releases by airplanes – often used in the application of the technique for other insects – may damage their wings and legs.
"The biggest challenge in designing this mechanism was keeping the mosquitos healthy and competitive while transporting and releasing them at cool temperatures" said Adam Klaptocz, co-founder of WeRobotics. "We're pleased with initial tests that show less than 10 per cent mortality through the entire chilling, transport and aerial release process."
Until now, sterile mosquitos have been released using time-consuming and labour-intensive ground methods. “With the drone, we can treat 20 hectares in five minutes,” said Bouyer. Weighing less than 10 kilograms, the drone can carry 50,000 sterile mosquitos per flight. At 10,000 Euro per drone, its use also reduces the cost of releasing mosquitos by half.
Brazil plans to start using the drone-based system in selected urban and rural areas from January 2019, at the peak of the summer and mosquito season. “We are hopeful about the application of SIT for the control of Aedes aegypti in Brazil with the results from the drone tests,” said Jair Virginio, Director of Brazil-based Moscamed, a recently-designated IAEA Collaborating Centre.
The IAEA and its partners are now working to reduce the drone’s weight and to increase its capacity to carry up to 150,000 mosquitos per flight. The development of the drone was supported by a grant from the United States Agency for International Development.
SIT has been used for over 50 years to fight agricultural pests such as the Mediterranean fruit fly, and has only recently been adapted for disease-transmitting mosquitos. The insect control method can be particularly useful against vectors that are difficult to manage using conventional techniques, such as nets impregnated with insecticide, or when there is a need to reduce the use of pesticides.
The push for the development of SIT to control mosquitos became more urgent as the Zika epidemic unfolded in Brazil and Latin America in 2015-2016. Through its Technical Cooperation Programme, the IAEA provided assistance to affected countries to rapidly diagnose the disease and to boost regional capacity to apply SIT against the vector of diseases.