Kao Corporation (News Release)
Building a virtual space specializing in mosquito observation with RIKEN Apparently, he remembers the smell of silicone oil on his legs and takes evasive action.
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Kao Corporation (President: Yoshihiro Hasebe) Human Healthcare Research Institute is collaborating with the National Institute of Physical and Chemical Research’s Perceptual Neural Circuit Mechanism Research Team at the RIKEN Center for Brain Science to precisely control the behavior of mosquitoes in response to various sensory stimuli. We have built a virtual space that allows you to understand details.
Kao has reported in previous research that mosquitoes do not stay on surfaces coated with low-viscosity silicone oil*1. As a result of experiments using the newly developed device, adhesion of silicone oil to the legs caused a decline in the mosquito’s tracking ability. Furthermore, we confirmed that mosquitoes perform associative learning, which involves associating and remembering experiences and odors, and found that mosquitoes may take avoidance actions in response to memorized odors when they have had unpleasant experiences. The results of this study were published in Nature Research’s electronic journal Scientific Reports in March 2024*2.
[Image 1: https://prtimes.jp/i/70897/413/resize/d70897-413-762bbbe93570755a66ce-0.png&s3=70897-413-5728a984c2b465d66557201403ccfc09-828×598.png ]
*1 December 9, 2020 Kao News Release Developing technology to prevent mosquito bites by creating a skin surface that mosquitoes dislike – Protecting against mosquito-borne infectious diseases –
*2 Wiedemann BM., Takeuchi,K., Ohta,K., Kato-Namba,A., Yabuki,M., Kazama,H., Nakagawa,N., Hydrophobic solution functions as a
multifaceted mosquito repellent by enhancing chemical transfer , altering object tracking, and forming aversive memory Scientific Reports volume 14, Article number: 5422 (2024)
■Background
Approximately 1 million people die each year from mosquito-borne infectious diseases such as dengue fever and malaria, and it is necessary to protect ourselves from mosquito bites. Kao discovered that when low-viscosity silicone oil, which is used in cosmetics, is applied to the skin, mosquitoes do not stay on the skin and
immediately take flight*3, and developed a unique mosquito repellent that takes advantage of this property. We are developing. During the development process, we noticed that after mosquitoes fly away from skin coated with silicone oil, they move in a manner similar to wiping the silicone oil off their legs. Therefore, we constructed a virtual space that allows us to more accurately understand the response of mosquitoes to silicone oil, and conducted experiments.
*3 Low-viscosity silicone oil has the property of quickly spreading on the hydrophobic legs of mosquitoes, and when it comes into contact with it, it exerts a strong force that pulls the mosquito’s legs towards the silicone oil. For mosquitoes, this attraction poses a threat and is thought to induce escape behavior.
*3 Low-viscosity silicone oil has the property of quickly spreading on the hydrophobic legs of mosquitoes, and when it comes into contact with it, it exerts a strong force that pulls the mosquito’s legs towards the silicone oil. For mosquitoes, this attraction poses a threat and is thought to induce escape behavior.
■Building a unique virtual space specialized for mosquitoes
The joint research team has constructed a virtual space “specific to mosquitoes” in which mosquitoes feel as if they are flying freely according to their own will (Figure 1). This device collects and measures the sound of flying mosquitoes’ wings with a microphone, analyzes the direction in which the mosquito wants to fly, and changes sensory stimuli such as surrounding images and odors accordingly. Because the sensory stimulation can be changed every 0.005 seconds, it is possible to capture minute behavioral changes in mosquitoes and infer how various sensory stimuli are received.
[Image 2: https://prtimes.jp/i/70897/413/resize/d70897-413-15cfef18aef3cf975f4f-0.png&s3=70897-413-d9a65f2cdaaa1496e595e7623dc5742a-627×425.png ]
Building a unique virtual space specialized for mosquitoes
■Experiment 1. When low-viscosity silicone oil gets on the legs, the ability to chase moving objects decreases Normally, when a black object (stick) that moves according to the behavior of the mosquito is displayed on the LED panel in virtual space, the mosquito follows the stick and flies so that the stick is always in front of him. However, mosquitoes with silicone oil on their legs were no longer able to successfully track the rod (Figure 2). This indicates that adhesion of silicone oil to the legs causes a decline in the mosquito’s tracking ability.
[Image 3: https://prtimes.jp/i/70897/413/resize/d70897-413-66709b48eedadb953141-0.png&s3=70897-413-9c5f124709e0623e5fca8218c6070562-895×295.png ]
Figure 2. Image diagram of mosquito flight trajectory
■Experiment 2. Memorize the odor of low-viscosity silicone oil and take evasive action
It has been reported that mosquitoes associate the physical stimulus of being about to be hit with the odor they smell at that time, remember it, and avoid that odor. Therefore, we hypothesized that the animals would also remember the smell of silicone oil on their legs, and this would change their behavior.
This time, the research group applied silicone oil and glycerol*4 to the legs of mosquitoes and compared their behavior in virtual space. At that time, we mixed citronella oil, which is known to have a smell that mosquitoes hate, as both are odorless. After adhesion, we presented the odor of citronella from a tube and observed its flight behavior. If the silicone oil got on its legs, it would spend more time flying to avoid the direction where the odor of citronella was coming from, and it would avoid citronella more strongly. I saw action. On the other hand, no change in flight behavior was observed in the case of glycerol. Mosquitoes are thought to associate the experience of having silicone oil on their legs with the citronella they smell at that time (associative learning). From this result, we discovered that mosquitoes may take avoidance actions against odors that they remember from unpleasant experiences.
*4 Unlike silicone oil, glycerol does not spread on the legs of mosquitoes and does not affect their behavior.
■Summary
By constructing a virtual space optimized for mosquitoes, it has become possible to understand the detailed behavior of mosquitoes in response to various sensory stimuli. As a result of the experiment, silicone oil attached to the legs caused a decline in the mosquito’s tracking ability. Furthermore, we confirmed that mosquitoes perform associative learning, which involves associating and remembering experiences and odors, and found that mosquitoes may take avoidance actions in response to memorized odors when they have had unpleasant experiences.
More details about this release:
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