Mosquitoes
have ears.

He is a researcher who has used neuroscience to uncover how insects respond to sound and odor. Professor Kwon trained in entomology and has focused primarily on mosquitoes and honeybees.

The Institute of Vector-Borne Disease Research at Incheon National University, which he directs, uses mosquitoes as an insect model and combines neuroscience, mechanical engineering, and artificial intelligence in vector-control research. The work has expanded from observing insects to developing control technologies based on insect biology; its in-house AI mosquito analysis system is one example.

They follow carbon dioxide, body heat, and odors emitted by people and animals. Mosquitoes use these signals as clues to locate targets from a distance. When they get close and determine that the source is not a person or animal, they turn back. Their sensory organs are that finely tuned.

• Carbon dioxideTracks changes in CO₂ concentration from a distance
• OdorIdentifies chemicals from sweat and skin through olfactory receptors
• VisionUses visual cues to narrow down a target after detecting odor
• HeatDetects temperature differences caused by body heat at close range

These are the senses mosquitoes use to find people. Separately, mosquitoes also have a dedicated organ for detecting sound.

• SoundDetects sound waves through Johnston’s organ in the antennae - the starting point for MOSLOCK’s ultrasonic mosquito-repellent research and development

Yes. It is called Johnston’s organ. Named after its discoverer, it serves a role comparable to the human ear. Located at the base of the antenna, it contains a dense concentration of auditory neurons.

Johnston’s organ is known to respond well to sound waves in the approximate 100-1,000Hz range. An electrophysiological study of male northern house mosquitoes (Culex pipiens) reported at least eight groups of auditory neurons tuned to different frequencies, with individual tuning frequencies distributed from 85 to 470Hz. It is considered one of the most complex mechanosensory structures found in insects.

By measuring electrical signals or imaging changes in living tissue.

The first method is electrophysiology. Just as hospitals measure electrical activity in the heart (ECG) or brain (EEG), researchers directly record the activity of neurons concentrated in Johnston’s organ. If the mosquito detects sound, an electrical signal appears at that moment.

The second method is live imaging, which observes tissue changes in real time after stimulation. The same approach is used with honeybees and fruit flies as well as mosquitoes.

Not because mosquitoes lack hearing, but because the devices did not deliver a meaningful acoustic stimulus to them.

Ultrasonic repellents have been controversial since the 1990s. Multiple validation studies failed to confirm repellency, causing distrust of the entire product category. Professor Kwon points to two reasons.

1. The repellent frequencies were not identified There are frequency ranges that mosquitoes avoid, but earlier research lacked sufficient methods to identify them scientifically.
2. The sound pressure was too low Even at the right frequency, a weak sound is effectively no stimulus at all from the mosquito’s perspective.

In short, the negative verdict was less ‘ultrasound does not work’ and more ‘devices that fail to meet the necessary conditions do not work.’ The next research question was whether those conditions could be met - this became the challenge for subsequent commercialization research.

We redesigned three factors: sound pressure, space, and frequency.

* The multipliers mentioned in the interview are comparative values from the research process and may vary by measurement conditions.

Because living organisms adapt to repeated stimuli. When the same stimulus continues and is judged not to be a real threat, an organism gradually begins to ignore it. This is called habituation.

A mosquito follows the same pattern when exposed continuously to one fixed frequency: it is startled at first, then adapts. MOSLOCK therefore introduces unpredictable variation. Continually changing frequencies lengthens the time required for adaptation.

We use repellent-testing methods established by the World Health Organization (WHO) as a benchmark. Typical behavioral tests include exposing an arm or observing a person inside a test chamber.

Two additional layers are added: imaging to observe what happens in Johnston’s organ, and molecular analysis to determine whether receptors change. An effect is recognized only when behavioral, physiological, and molecular results point in the same direction.

The behavioral and molecular findings were published in a peer-reviewed paper. In 2021, the team reported ultrasound-associated approach suppression, reduced host-seeking behavior, and changes in sensory-related gene expression in Aedes aegypti. A related patent was filed during the commercialization R&D process, and a follow-up paper is also in preparation.

Because the validation had to expand in stages and be repeated for each real-world use environment. It was a process of repeatedly asking the same question while changing one condition at a time.

1. Expanding the stages of validation

1. Preliminary test - Confirm basic responses in a controlled indoor environment
2. Semi-field test - Revalidate under conditions designed to resemble the outdoors
3. Field test - Confirm whether results hold under real-world conditions

Each stage required a separate setup aligned with World Health Organization test methods. Different objectives called for different equipment, including chambers entered by a person and devices used to observe responses to an exposed arm.

2. Repeating tests for each use environment

Ultrasound is highly directional and does not travel far. This means the same device can produce different results depending on the size and shape of the space, so each real-world environment was tested separately.

• IndoorsCheck responses in enclosed spaces such as bedrooms
• Vehicle interiorCheck sound-pressure distribution and responses in a narrow space with many reflective surfaces
• Docking tentCheck the effective range in larger conditions such as car camping

Because sound-pressure coverage and mosquito hiding places differ by space, even device placement had to be tested repeatedly.

Near the head of the bed or by your feet. Mosquitoes often target the head and feet when seeking a blood meal because these areas produce strong carbon-dioxide and sweat cues.

The space also matters. Ultrasound is highly directional and has limited reach, so it is better suited to a somewhat enclosed space such as a bedroom than to a large open area.

If mosquitoes have Johnston’s organ, whether they can be influenced through sound was a question worth investigating. If mosquitoes could be managed through a physical method rather than chemicals, that alone made the subject worth pursuing. The research continued for nearly 20 years.

There is also a broader issue behind this research. One of the greatest challenges in mosquito control is insecticide overuse and the resistance it creates. Insecticides also affect insects other than mosquitoes, and heavier use causes greater environmental damage. Killing more mosquitoes is not always an unqualified good.

The direction is therefore shifting: from killing every mosquito to self-protective approaches that keep mosquitoes away from the individual.