Why mosquitoes aren't going away? Here's some good news and some bad news

"Buzz, buzz, buzz..."

One of the nightmares of summer: before going to bed, you carefully draw the mosquito net, but as soon as you lie down, you hear the buzzing of mosquitoes next to your ears, and then you can't help asking yourself -

Mosquito, why don't you die yet?

Actually, scientists have really worked hard to eliminate mosquitoes...

I really want to slap him in the face｜Pixabay

Make mosquitoes "extinct"

In a recent study, scientists in California, USA, used gene editing technology to interfere with the sexual development genes of Gambia mosquitoes, so that female mosquitoes can only give birth to male mosquitoes . [1]

The study targets the Anopheles gambiae mosquito, which spreads malaria . Malaria is one of the world's deadliest diseases, killing hundreds of thousands of people every year. The parasite that causes malaria is Plasmodium, which must rely on female Anopheles mosquitoes to spread , so by making the Anopheles gambiae mosquito only give birth to male babies, the spread of malaria can be blocked. Such technology may also be applied to deadly diseases such as dengue fever in the future.

Using gene editing technology to modify the genes of Anopheles gambiae larvae | today.ucsd.edu

In the above study, mosquitoes can at least have babies, but some scientists have made mosquitoes "infertile" . Mosquito: Listen to me, thank you~

Chinese scientists have previously modified mosquitoes using a microbe called Wolbachia , a symbiotic bacterium that affects mosquito reproduction: when males are infected and females are not infected with the same Wolbachia, they will be unable to reproduce after mating .

The researchers infected male mosquitoes with Wolbachia in the laboratory and then released them into the wild to mate with female mosquitoes to reduce the number of mosquito offspring. At the same time, they also used radiation to sterilize female mosquitoes carrying the same type of Wolbachia , further ensuring the effectiveness of reducing the mosquito population. [3]

Using this method, the researchers eliminated almost all of the Aedes albopictus mosquitoes on two river islands in Guangzhou .

Aedes albopictus can transmit a variety of pathogens including dengue virus and Zika virus. It is also known as the "flower-legged mosquito" | James Gathany, CDC

In addition to sterilization, some scientists have also tried to kill the mating process before it happens by turning mosquitoes into “deaf mosquitoes.” [4]

Male mosquitoes listen carefully to the buzzing sounds of female mosquitoes to find mates , and their auditory systems involve serotonin. The researchers fed mosquitoes serotonin-inhibiting compounds to interfere with their hearing, making them deaf to mating songs .

Making mosquitoes deaf is good, but it would be even better if we could make them "mute" so that we don't have to hear the annoying buzzing sound. Scientists are advised to conduct research quickly!

Filling the gap of mosquito-free winter

Here is some bad news about mosquitoes: Although scientists have tried very hard to eliminate mosquitoes, there are also many objective factors that extend the active time of mosquitoes, "filling the gap of no mosquitoes in winter"...

One important factor is climate change.

Don't come over here, you mosquito army｜Pixabay

In tropical regions, mosquitoes are active year-round, but outside of the tropics, low temperatures in winter can cause mosquitoes to hibernate. However, scientists predict that climate change will lead to longer summers and warmer winters, which could allow mosquitoes to come out and be active in warmer winters .

Researchers conducted experiments on mosquitoes in north-central Florida, a region on the border between subtropical and temperate climates. They found that mosquitoes are like extremely stretchy rubber bands, able to tolerate wide temperature ranges and able to withstand temperatures far above the local average ambient temperature measured by weather stations.[6]

This means that mosquitoes will not die from the heat in the summer, but the warm winter will allow them to play happily .

A corresponding discovery is that Finland recently recorded a new mosquito, called Culex modestus, which is the northernmost mosquito record found in Europe so far. Researchers say that although there is no risk of disease transmission at present, with global warming, more southern species will invade Finland in the future...

New mosquito, Culex modestus, spreads West Nile virus | Lorna Culverwell

Additionally, light pollution contributes to longer mosquito seasons .

A study found that nighttime city lights can disrupt the dormancy of mosquitoes, preventing them from sleeping properly and giving them more time to bite people. But there is also good news: the frequent activity of mosquitoes prevents them from storing enough energy to feed themselves, and they may die during their winter dormancy (which is good news, right?). [8]

Give your arms

While most mosquitoes bite all animals equally, some, such as the Aedes aegypti mosquito in some areas, prefer human blood.

Aedes aegypti mosquitoes are dangerous and carry Zika, dengue and yellow fever viruses. A study last year found that the little brains of Aedes aegypti mosquitoes are more sensitive to human odors, and then they can... bite humans . Zhao Zhilei, a Chinese graduate student who participated in the study, said that the commonly used laboratory method of "wrapping rabbit blood with a thin plastic film to simulate skin" does not work. The simplest and most efficient way is to directly put your arm into the mosquito cage .

Thanks to the researchers for their arms | Perran Ross

Devoting oneself to science! What an amazing human being!

Finally, here’s some good news for experimenters studying mosquitoes.

Many existing mosquito experiments rely on human volunteers and animal subjects, and being bitten for dozens of hours in experiments is simply inhumane, but machines can help .

The researchers used a 3D printer to make the skin, and each piece of hydrogel was filled with blood that could flow. When mosquitoes came to bite, there were cameras to record the frequency of mosquitoes landing at each location, the length of time they stayed, whether they bit, and when they fed.

Using 3D printers to make skin, each piece of hydrogel is filled with flowing blood｜news.rice.edu

Although it is not clear whether such a device can completely replace human arms, while researchers are diligently studying how to kill mosquitoes, at least some people are still concerned about their arms.

References

[1]Andrea L. Smidler, James J. Pai, Reema A. Apte, Héctor M. Sánchez C., Rodrigo M. Corder, Eileen Jeffrey Gutiérrez, Neha Thakre, Igor Antoshechkin, John M. Marshall, Omar S. Akbari. A confinable female-lethal population suppression system in the malaria vector, Anopheles gambiae. Science Advances, 2023; 9 (27) DOI: 10.1126/sciadv.ade8903

[2]https://today.ucsd.edu/story/new-genetic-technology-developed-to-halt-malaria-spreading-mosquitoes

[3]Hate mosquitoes? Chinese scientists have found a new way to kill them all | One Week Technology https://mp.weixin.qq.com/s/PeKsaydAPVN4zy9N5XxooQ

[4]Yifeng YJ Xu, YuMin M. Loh, Tai-Ting Lee, Takuro S. Ohashi, Matthew P. Su, Azusa Kamikouchi. Serotonin modulation in the male Aedes aegypti ear influences hearing. Frontiers in Physiology, 2022; 13 DOI: 10.3389/fphys.2022.931567

[5]https://www.nagoya-u.ac.jp/researchinfo/result-en/2022/11/20221116-01.html

[6] Brunno F. Oliveira, Wendtwoin IG Yogo, Daniel A. Hahn, Jiang Yongxing, Brett R. Scheffers. Community‐wide seasonal shifts in thermal tolerances of mosquitoes. Ecology, 2021; DOI: 10.1002/ecy.3368

[7]https://www.sciencedaily.com/releases/2021/06/210614185549.htm

[8]https://www.sciencedaily.com/releases/2023/04/230411105922.htm

[9]CL Culverwell, O. Vapalahti. First record of Culex modestus in Finland. Journal of the European Mosquito Control Association, 2023; 1 DOI: 10.52004/JEMCA2023.0003

[10]Zhilei Zhao, Jessica L. Zung, Annika Hinze, Alexis L. Kriete, Azwad Iqbal, Meg A. Younger, Benjamin J. Matthews, Dorit Merhof, Stephan Thiberge, Rickard Ignell, Martin Strauch, Carolyn S. McBride. Mosquito brains encode unique features of human odor to drive host seeking. Nature, 2022; DOI: 10.1038/s41586-022-04675-4

[11]https://news.rice.edu/news/2023/bite-mosquito-feeding-chamber-uses-fake-skin-real-blood

Author: Xiu Beng Beng

Editor: You Shiyou, Heijiomeimei

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