How Mosquitoes Use Six Needles to Suck Your Blood [Video Inside]
It’s a good thing you can’t really see what that mosquito is doing when it bites — you probably wouldn’t want to watch as it buries six needles into you. But scientists have been figuring out all the bloody details. And it’s not just for idle curiosity: mosquito bites are more dangerous to humans than any other animal bite. While female mosquitoes — only females bite us — are drinking our blood to grow their eggs, they can leave behind viruses and parasites that cause diseases like West Nile, Zika, malaria and dengue.
Key Facts:
- Only female mosquitoes bite humans. They need blood to make eggs.
- Here’s how a mosquito’s proboscis works to suck your blood.
- The chemicals she uses to make your blood flow more easily are the ones that give you the itchy welt afterward.
Part of what makes mosquitoes so good at getting humans sick, researchers say, is the effectiveness of their bite. Scientists have discovered that the mosquito’s mouth, called a proboscis (pronounced pro-BOSS-iss), isn’t just one tiny spear. It’s a sophisticated system of thin needles, each of which pierces the skin, finds blood vessels and makes it easy for mosquitoes to suck blood out of them.
Mosquitoes also have more than 150 receptors — proteins on their antennae and proboscis that help them find victims or figure out if the water is nutritious enough to lay eggs in. When malaria-causing Anopheles mosquitoes come out at night to look for blood, they track the carbon dioxide we exhale as we sleep. As they get closer to us, they detect body heat and substances called volatile fatty acids that waft up from our skin, said University of California, Davis, parasitologist and entomologist Shirley Luckhart.
“Why are some people more likely to get bitten than others?” asked Luckhart. “The volatile fatty acids given off by our skin are quite different. They reflect differences between men and women, even what we’ve eaten. Those cues are different from person to person. There’s probably not one or two. It’s the blend that’s more or less attractive.”
Researchers still haven’t figured out what about their volatile fatty acids makes some people more attractive to mosquitoes than others. What scientists have recently discovered is that once a mosquito’s proboscis pierces the skin, one of its six needles, called the labrum, uses receptors on its tip to find a blood vessel.
“Those receptors responded to the chemicals in the blood,” said UC Davis biochemist Walter Leal, whose lab made the finding. “Mosquitoes don’t find the blood vessel randomly.”
Scientists have been trying to figure out the anatomy of the mosquito bite for decades. It’s a job made difficult by the challenge of dissecting mosquitoes’ delicate mouthparts, which tend to fall apart in the hands of beginners. Choo attributed his dissecting abilities to his experience using chopsticks in his native South Korea. Video, powerful microscopes and genetic analyses have helped researchers figure out how the feeding system works.
Mosquitoes don’t get anything out of making us sick ― they just incidentally pass germs onto us. In fact, researchers have found that some viruses started out as mosquito-only viruses. This isn’t hard to believe, as mosquitoes developed 200 million years before humans.
“As mosquitoes evolved the habit of drinking blood, some viruses have tracked that evolutionary path and become human-vectored viruses,” said microbiologist Shannon Bennett, chief of science at the California Academy of Sciences.
via: kqed.org
