China is developing a super-sensitive radar that can detect the wing-flapping of a mosquito up to 2 kilometres away, according to a senior scientist involved in the government research project.
A prototype of the device is being tested at a defence laboratory at the Beijing Institute of Technology (BIT), said the researcher, who declined to be named as the project involves sensitive technology used in China’s missile defence system.
“Identifying and tracking individual, mosquito-sized targets is no longer science fiction,” he said. “We are actually quite close to bringing this technology out of the laboratory and using it to save lives.”
Mosquitoes have claimed more human lives than all wars combined – their infectious bites still cause more than one million deaths each year, according to the World Health Organisation.
The insect plays host to a wide range of disease-bearing microorganisms, from malaria to newer viruses such as Zika.
Controlling the pest is a major challenge though, as they can come and go almost without a trace – their familiar buzzing is a giveaway, but only when they are close by.
After decades of development, modern military radars can now pick up the echoes of small objects at an impressive distance. The US Missile Defence Agency’s sea-based X-band radar, for example, can detect a baseball-sized object from about 4,000km (2,500 miles) away.
China has developed radar systems with similarly advanced features to track missiles and stealth aircraft, but some scientists working on these military projects believed the technology could also be used to fight mosquitoes – and they convinced the government to fund their research.
The team, led by Long Teng, received funding of more than 82 million yuan (US$12.9 million) from the central government at the end of last year to build a full-sized mosquito detection radar that could be tested in the field.
Long is director of BIT’s Radar Technology Research Institute and a lead scientist on China’s key military radar programme, according to the university’s website. He could not be reached for comment.
The radar works by emitting rapid pulses of electromagnetic waves that travel at many frequencies, according to the scientist working on the project. When the radio waves hit a mosquito they bounce back with information including species, gender, flying speed and direction, and whether the insect has eaten.
It could be mounted on a rooftop overlooking a residential community and used to pinpoint the position of major mosquito colonies, their breeding and resting areas. And if a colony was migrating to another neighbourhood, households in its way could be warned.
Scientists in other countries have used civilian radar networks to track the group movement of birds or larger insects such as locusts and moths, but this is believed to be the first attempt to use radars to monitor mosquitoes.
The researcher said the prototype had achieved unprecedented sensitivity because the authorities had allowed the team to build the system using the latest military radar technology.
It has, for example, an advanced phased array antenna similar to those used on China’s latest warships. The antenna can beam microwaves in different directions at the same time and can detect missiles or military jets much faster than conventional radars that use a rotating dish.
It also has a separate antenna to generate radio waves oscillating in more than one direction. Known as polarisation, this provides detailed information about a target so that the researchers can distinguish a hungry, blood-sucking female mosquito from a pollen-eating male.
A fast computer then uses an algorithm to simultaneously identify and follow the movement of many mosquitoes in the same community.
The project is a collaboration between insect behaviourists and scientists from many other disciplines, according to the researcher. By providing a vast amount of data, the radar has the potential to help biologists learn more about the individual and collective behaviour of the pest, which could lead to new strategies to fight the spread of mosquito-borne diseases.
The researcher added that the team had made progress on the existing technology and it could also have military applications, without elaborating. He also declined to say when the first full-sized radar would be completed.
“We are building one or two units at the moment. In the future we hope the radar will be made in large numbers and installed across the country to form a large network to monitor the movements of airborne animals [as well as mosquitoes],” he said.
Yi Zhenyuan, an award-winning military radar researcher and deputy director of the electrical engineering department at Harbin Institute of Technology, said identifying and tracking such a minuscule target from kilometres away was extremely difficult.
Existing military radar technology could detect small, uncooperative signals from hundreds to thousands of kilometres away, but mosquitoes were “another story”, he said.
Yi, who has knowledge of the radar but is not involved in the project, said mosquitoes would be more difficult to detect than a stealth aircraft like the F-22, which has a special coating and geometric design to avoid showing up on radar screens.
“Mosquito wings of course are a lot different from the metal wings of a military jet, and so are their structures, shapes and movements. The mosquito radar is going to need a completely new set of algorithms,” he said.
Mosquitoes also fly at low speed, sometimes just hovering in the air, which makes some of the military radar technology designed to detect fast-moving targets less useful to the project.
The biggest challenge will come from the environment, Yi said, since the radio waves from a mosquito were extremely weak and could easily be overwhelmed by background noise.
“So what works perfectly well in a laboratory may not be so successful out in the field,” he said.