Is electronic mosquito repellent possible?

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Legendary mechanism of sound wave mosquito repellent

The myth explains the mechanism of electronic mosquito-repellent incense in this way: male mosquitoes only rely on nectar, plant juice and other nutrients, and do not suck blood; Female mosquitoes must suck human and animal blood to reproduce and lay eggs; Male mosquitoes will constantly emit sound waves of courtship, but pregnant female mosquitoes will try to avoid male mosquitoes because they don't want to repeat pregnancy. Mosquito repellent is to use this principle to simulate the frequency of the sound made by the vibrating wings of male mosquitoes to scare away female mosquitoes and achieve the effect of mosquito repellent. [ 1]

Is this statement reliable? This has to start with the habits of mosquitoes.

Most species of mosquitoes form a large group of males within a few days after pupation. I think students who often wander around the lake in summer have seen such breeding groups. Females will be attracted by the sound of a large group of males flapping their wings and enter the group to find a mate [2]. The female reproductive organs of all insects, including mosquitoes, have a structure called seminiferous membrane. Usually, the sperm stored in the sperm membrane after a normal mating is enough for her to live, but this does not mean that the females of various mosquitoes will refuse to mate many times. Therefore, the statement that "pregnant female mosquitoes will try to avoid male mosquitoes because they don't want to repeat pregnancy" is not reliable.

The "sound wave" we are talking about here is actually the sound wave generated by the vibration of mosquito wings. The vibration frequency of mosquito wings is about 250 to 1000 times per second, and its sound wave frequency range is basically between 250Hz and 1000Hz. Mosquitoes can hear the sounds made by other individuals' wings, but the frequency of wing vibration is related to the species of mosquitoes, and this value varies from mosquito to mosquito. Therefore, even if a certain frequency band of sound waves can really drive away some mosquitoes, it can't be effective for all mosquitoes-you know, there is not only one kind of mosquitoes that harass you.

Since mosquitoes can't send out ultrasonic contact signals, why are many acoustic mosquito repellents advertised as "ultrasonic mosquito repellents"? Some manufacturers publicize that "mosquito repellent generates ultrasonic waves similar to male mosquitoes flapping their wings to drive away female mosquitoes", which is actually a big joke. There is indeed an "ultrasonic mosquito repellent" in the western market, but it is imitating the sound of bats, the natural enemy of mosquitoes. As we all know, bats use ultrasound to locate their prey. Some insects (such as some Noctuidae) have evolved organs that can recognize ultrasonic waves in order to resist the predation of bats, and they can escape after hearing the sound of bats.

So, is the mosquito repellent made by this principle effective? Don't look at the advertisement, look at the curative effect!

Effect of ultrasonic mosquito repellent products on potholes

Electronic mosquito repellent appeared in the western market for several decades, during which it was constantly questioned, and most mosquito repellent devices failed to pass the scientific inspection.

Scientists have done a series of experiments [4][5][6], and evaluated the effects of 1 1 ultrasonic mosquito repellent with a frequency of 2 ~ 60 kHz and a harmonic peak of 4 ~ 68 kHz on Aedes aegypti, Culex pipiens, Anopheles quadriceps, Aedes albopictus and Haemophilus at different distances. It was found that none of the tested products could successfully stop the bites of these mosquitoes under the field and laboratory conditions.

On the government side, the US Federal Trade Commission and the State Environmental Protection Agency conducted a rigorous review of ultrasonic mosquito repellent products, saying that there is not enough evidence to prove that such products can repel pests or mice. In addition, the Indian state government of the United States also requires 44 manufacturers of ultrasonic insect repellent (rat repellent) to provide test data to prove that their products are indeed effective. Finally, only five manufacturers gave a reply, and the data provided by these five courageous manufacturers could not support that their products were really effective. Obviously, these mosquito (rat) repellent products do not have the magical effect boasted by manufacturers. [7]

Cell phones, ultrasound and what people have to say.

To take a step back, let's assume that electronic mosquito repellent, which imitates bat ultrasound, is really effective. The frequency of sound waves emitted by bats is at least above 10kHZ, even higher than 10KHz [8]. Therefore, if these "mosquito repellents" are effective, they must be able to emit sound waves including the ultrasonic frequency band. For the human body, ultra-large doses of ultrasound for a long time may cause damage to human cells. When people use ultrasonic waves, they also need to strictly control the intensity to ensure safety.

Fortunately, the so-called ultrasonic mosquito repellent software has reached a certain level, and it can't emit ultrasonic waves at all, but it avoids the possible harm to users unintentionally.

In fact, as early as a few years ago, ultrasonic mosquito repellent software appeared on PC, but it also had no effect. Although the treble upper limit of some speakers is claimed to be as high as 30kHz, the civil multimedia speakers are all designed according to the hearing range of human ears from 20 Hz to 20kHz, and the sound often begins to attenuate at 18kHz, and there is almost no attenuation in the frequency band above 20 kHz. Therefore, if you expect to use ultrasonic mosquito repellent software on your computer to repel mosquitoes, you have to spend a lot of money to save a set of hifi equipment (high fidelity). It's really hard to just expect your computer to generate ultrasonic waves to drive away mosquitoes with ultrasonic mosquito repellent software. Beijing Youth Daily once commissioned experts to test mosquito repellent software, and the test results showed that several so-called ultrasonic mosquito repellent software could not emit ultrasonic waves [9]. Even the computer speaker can't guarantee to emit ultrasonic waves, let alone the mobile phone.

In order to create mosquito repellent effect, some products will make a "buzzing" sound, which is not only funny, but also annoying. Otolaryngology experts say that people's ears are prone to irritability, physical discomfort and even tinnitus under monotonous sounds such as "buzzing" for a long time.

Reprinted from:/Ada/Details? id=4768

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