If humans have instant noodles, this is the same product for mosquitoes. It is the result of a science that is more than seven decades old.
You must have seen this meme somewhere on the internet, a doctor drawing his own blood, pouring it into a petri dish and saying to the mosquito: “Eat it! Then leave my legs alone“. But will that scenario happen in real life?
A mosquito eats live blood, meaning it drinks blood directly from outside the human body?
According to the experience of many scientists, the answer is: No!
You can’t feed mosquitoes by pouring your blood out and expecting them to come in and drink it the way ants find sugar drops.
That’s because mosquitoes are attracted to the smell of sweat on human skin, not the smell of blood. They like to drink fresh, warm blood and suck it directly out of the human body. That instinct tells mosquitoes to be the best source of nutrition they can have.
Scientists, therefore, still have to use their own arms to feed mosquitoes in the laboratory:
Record: Scientist gives 5,000 mosquito bites a day for science
Feeding mosquitoes: Science is more than 7 decades old
In the video above is the arm of Perran Ross, an entomologist at the University of Melbourne, Australia. He is feeding about 500 Aedes aegypti mosquitoes in his cage.
Ross uses these mosquitoes to study dengue. Every day, he has to feed 5,000 mosquitoes in 10 cages like this. From sunrise to sunset, they will take 16 ml of blood from Ross.
Since 2012, when Ross started his master’s thesis related to mosquitoes, he has lost a total of 8 liters of blood to feed his insect colonies. “If they all burned me at the same time, I would probably die from blood loss,” he said.
It is a possible reality, in some projects, scientists will have to raise millions of mosquitoes, then release them into the wild. Each female mosquito only needs to suck 5 microliters of blood, then just 1.1 million mosquitoes, all the blood in your body will be drained.
Unfortunately, you will die when the 440,000th mosquito has finished its lunch. That’s because you can’t lose 40% of your body’s health and stay alive.
After that, the 440,001 mosquito will most likely leave behind your cold and unattractive body. Mosquitoes never suck blood from dead people.
So unless you have dozens to hundreds of volunteers willing to donate blood to feed the mosquitoes every day, the strategy of hand-feeding mosquitoes is not a smart way to breed millions of mosquitoes.
So what will scientists do?
That is the question that has puzzled scientists for seven decades. The first evidence of a mosquito feeding system was found in 1949, in a study published in the journal Mosquito News. Its author Greenberg. J has built a machine that feeds the Aedes aegypti mosquito.
The machine has glass tubes of blood, placed in copper cylinders to be continuously warmed by electricity. At each end of the glass tube is covered with a film by Greenberg. Mosquitoes can stick their proboscis through it to suck blood.
Ironically, however, not all mosquitoes are attracted to the man-made membrane. The disadvantage of this machine is that it is also very bulky and requires to be powered by electric current.
So some scientists in the 1950s tried to improve on Greenberg’s idea. In 1956, Boorman and Potterfield built a simple heating system powered by circulating hot water.
The duo used mouse blood mixed with heparin, an antifreeze, to attract mosquitoes. They also replaced the artificial membranes with the skin of adult mice themselves. This is thought to have attracted mosquitoes to their natural diet.
Over the next decade, scientists experimented with new mosquito-feeding ideas, ranging from simple to complex. Some simply pour warm blood into the chicken’s diverticulum and hang it up. Others make complex blood mixtures, mixing them with sodium citrate to create a flavor more appealing to mosquitoes.
Improved heating systems, the goal is to keep the blood warm at about 37-40 degrees, close to human body temperature. Some mosquito feeding systems are also equipped with a stirring device.
But the most important is still the membrane. Membrane is something that simulates human skin, it is likened to a mosquito’s dining table. Mosquitoes won’t drink blood directly, instinct tells them to find the membrane and stick their proboscis through it.
The more realistic the membrane simulation, the closer scientists will be to a perfect mosquito feeding system. When it does, it can replace their arms, so that feeding mosquitoes in the laboratory is no longer a torture.
This scientist has created a wonderful membrane, to store blood in convenient “instant packages” for mosquitoes
Over the course of 5 decades, many materials have been tested. Scientists have tried using mouse skin, chicken skin, cow intestine. Some look to man-made materials such as silicone, collagen and even nylon fabric.
And then they found parafilm. Parafilm is a thin, semi-transparent and flexible film. It is made from a mixture of wax and polyolefin – a thermoplastic, malleable and non-toxic plastic.
You can even eat pafafilm even though they are odorless and tasteless. The most interesting feature of this material is that it is self-sealing. So when a mosquito sticks its proboscis through it and pulls it out, the parafilm heals.
Most mosquito feeding systems in the 21st century use parafilm. However, Omid Veiseh, a bioengineer at Rice University, says parafilm is not without its downsides.
This material has not yet simulated the thickness and elasticity of human skin. It also doesn’t allow scientists to apply chemicals to it. For example, when they wanted to apply human sweat on parafilm to attract mosquitoes, the material of the material was not the same as skin, the sweat simply deposited on it.
The same goes for mosquito repellents and insect repellents.
So, in an attempt to fix that, Veiseh and his lab colleagues built a hydrogel that mimics human skin. It is soft and spongy, but still enough for mosquitoes to detect blood underneath.
Veiseh then uses a 3D printer to print the material, forming tiny blood packets the size of a fingernail, inside which there is a zigzag channel that can be connected between multiple packets.
Real human blood is pumped into the canal. “It feels like a piece of jelly,” Veiseh said. “The mosquitoes have to bite through the jelly to suck blood.”
Ross, the scientist who is feeding 5,000 mosquitoes a day that you see on the video at the top of the article said: “Advantage of this system is that it’s trying to mimic human skin without using real human skin. This will be useful in researching mosquito repellents. It’s a great way to do that, in case you can’t use real people.”
To test their system, Veiseh and colleagues did an experiment. They linked six hydrogel packs together in chains, creating a buffet table that could house 20-30 mosquitoes at a time.
The scientists then applied two types of mosquito repellent to the hydrogel packets. The remaining one-third of the hydrogel packs were left as a control.
The results observed by the camera showed that when the hydrogel was soaked with the insect repellent, the mosquitoes did not have access to the blood in the packages. They still suck blood from normal hydrogel sacs.
“Dit was a big eureka moment for us“, says Veiseh. This proves that hydrogels mimic skin well enough to lure mosquitoes to feed. And they also work as usual in the presence of mosquito repellent.
These ready-to-eat mosquito blood packs are also useful for scientists who want to create genetically engineered mosquitoes and then release us wild, says Ross. “Before you do any field release, you have to evaluate those mosquito strains in the lab, and these hydrogels can help researchers pick the best mutants.“, he said.
Dawn Wesson, a medical entomologist from Tulane University, adds that the gels could be used to design a community warning system — a platform that attracts and observes mosquitoes in an area. area before they spread infectious disease.
“If you’re trying to detect infection in wild mosquitoes, releasing hundreds of these blood packs in the field with a monitoring system can be helpful.“, Wesson said.
As a scientist who has personally fed mosquitoes for more than 10 years, Ross suggests an innovative direction for Veiseh’s hydrogel packs:
“Mosquitoes are really complex creatures, and they’re very good at hunting you down from long distances. They use carbon dioxide, body odor, humidity, visual contrast and even color to select items. Unless you add in all the other signals that attract mosquitoes, you get the full effect.”
Until then, our famous meme will become a reality. If a scientist doesn’t want to be bothered by mosquitoes. They can draw their own blood, pump it into a hydrogel pack, and throw it out to the mosquitoes. Then their feet will be truly at peace.
(Ref: Wired, Rice, Pubmed, Discovermegazine, Sciencedirect, Washingtonpost, Cabdirect)