Why are mosquitoes so good at spotting humans?

 There is nothing like the odor of human sweat to attract female mosquitoes. The chase can begin more than 100 feet away, as a stream of air sends carbon dioxide to the sensory organs above the mosquito's mouthparts. Its senses are tempted to fly towards the human until its tentacles begin to excite the pungent smell of human skin. It follows the host's body temperature and gets a little closer, then falls on the host's skin somewhere, and feels it with the legs first. It pierces the victim's skin with spear-like needles and sucks the iron-rich blood from the victim's body.

The whole ritual is complex and persistent - almost impossible to interrupt. Of the more than 3,500 species of mosquitoes on Earth, less than 10 percent (and only females) like to bite humans. But once they set their sights on humans, nothing rain, mosquito killers or citronella candles can stop them. From the ends of their antennae to the soles of their feet, these human-loving mosquitoes are equipped to sense humans, says Leslie Warshall, a neurobiologist at The Rockefeller University. "They're really looking for us."

Even aggressive genetic interventions are not enough to divert mosquito bites. Aedes aegypti, a mosquito with stripes on its legs that likes to feed on human blood, can pass viruses such as dengue, Zika, and yellow fever into our blood. The genome of Aedes aegypti encodes more than 300 different chemical sensors that help the mosquito navigate its world.

Researchers managed to fine-tune more than 100 of these genes at once, but the mutated mosquitoes "still find and bite humans," said Boston University neurobiologist Meg Younger. It really struck me.

Warshal's team found that mosquito olfactory neurons don't respond to just one odor. Instead, mosquitoes have many olfactory neurons that recognize several odors. Like a universal socket adapter, their surfaces are covered with multiple types of receptors, all with slightly different configurations. It is no longer necessary to activate neuron A, neuron B, neuron C in order to transmit the signal to the brain that "there is a snack ahead", each neuron has the potential to transmit this information individually. These neurons come in handy when people's blood is on the menu.