What if you could be invisible to mosquitoes?

If you had only one superpower, flight or invisibility, which would you choose? And would your answer change if you could be invisible to mosquitoes?

Sure, you can never climb into the middle of an eagle or brush your cheek against a gust of cloud. But you too will no longer run away from the clouds of mosquito swarms, and you will be saved from the deadly diseases that insects spread.

For the first time, scientists have used the gene-editing tool Crisp-Cas9 to effectively become invisible to the human eye. aedes aegypti Mosquitoes, which use dark visual cues to hunt according to a paper Recently published in the magazine current biology. By eliminating two of that mosquito’s light-sensing receptors, the researchers knocked out its ability to target hosts visually.

“Nobody has studied it before,” said Neha Thackeray, a postdoctoral researcher at the University of California, San Diego, who studies Crisp as a mosquito control tool. Thackeray, who was not involved in the research, said he Viewed the study as a “great start” to controlling for mosquito vision.

aedes aegypti Salt and pepper is wreaking havoc on humans all over the world. Females, in order to lay their eggs in search of blood, infect millions of people each year with flaviviruses, which cause dengue, yellow fever and zika.

“The better we understand how they understand humans, the better we can control mosquitoes in an environmentally friendly way,” said Yinpeng Zhan, a postdoctoral researcher at the University of California, Santa Barbara, and lead author on the paper.

The malaria-carrying Anopheles mosquito hunts at night, while Aedes aegypti hunts at dawn and dusk under the sun. The species relies on a fleet of senses to find blood. A mere gust of carbon dioxide, a sign that someone or something has exhaled nearby, sends the mosquito into a frenzied flight.

“They can also detect certain organic signals from our skin,” said Craig Montell, a neurobiologist at the University of California, Santa Barbara, and an author on the study. But if there is no suitable host, the mosquito will fly directly to the nearest target: a dark spot.

In 1937, scientists observed that aedes aegypti Mosquitoes were especially attracted to people in black clothes. But the molecular mechanism by which the mosquitoes observed their targets was largely unknown.

Many experiments on the sight of mosquitoes take place in wind tunnels, large chambers that can cost tens of thousands of dollars. In earlier experiments, mosquitoes were placed in a wind tunnel and given a whiff of carbon dioxide, they chose to fly over a dark spot over a white one.

Montel’s lab doesn’t have a wind tunnel, so Zahn devised a cheaper setup—a cage with a black circle and a white circle inside—that cost less than $100 and produced similar results to a wind tunnel. In the spring of 2019, Zahn conducted spot tests in the cage. In the fall, Jeff Riffel, a biologist at the University of Washington, along with Claire Rusch, a graduate student, and Diego Alonso San Alberto, a postdoctoral fellow, ran the same experiment using a wind tunnel to double-check the original results.

a protein knock out

Montel and Zan suspected that one of five light-sensing proteins expressed in the mosquito eye may be the key to eliminating the ability of human hosts to see by sensing dark colours. First, they decided to knock out the rhodopsin protein Op1. Op1, the most widely expressed vision protein in the mixed eyes of the mosquito, seemed to be the best candidate to interfere with the mosquito’s vision. Zahn injected the mutation into the eggs of thousands of tiny mosquitoes using a device with a special needle with a very tiny tip.

After his wee mutants became adults, Zahn sucked 10 or more females into a tube using a controlled aspirator by mouth. With each group, they held their breath, went into the cage and released the females with a big breath.

The op1 mutants behaved exactly like wild-type Aedes aegypti: after huffing off carbon dioxide, they flew directly to the black dot in the cage. Montel and Xan tried again, this time outcrossing Op2, a closely related rhodopsin. Nevertheless, the Op2 mutants did not show any meaningful decline in their vision.

But when the researchers took out both proteins, the mosquitoes circled aimlessly, showing no preference between the white circle and the dark circle. They had lost the ability to find dark-coloured hosts.

Were mosquitoes completely blind, or just blind to people?

To answer this question, Montell and Zahn conducted a series of tests to see how the double mutants responded to light.

First, they tested whether the double mutants would grow towards the light. Next, they attached electrodes to the eyes of the double mutants to measure whether the eyes displayed a voltage change in response to light. Finally, they rotated the double mutants in cylinders with vertical black and white stripes to see if the insects would move in the direction of the moving stripes. The double mutants passed all three tests, although they had a weaker response than the wild types in the last two tests.

After all, mosquitoes weren’t blind. “My first transgenic mosquito,” Xan said proudly. “We had a happy ending.”

The new paper may inform future strategies for controlling mosquito populations. If female mosquitoes can’t see the hosts, they will have a harder time finding the blood they need to develop their eggs. “The population will crash,” Montell said.

This article originally appeared in the new York Times.