Natures wonders: male mosquitos don't bite, won't drink (Introduction)

by David Turell , Monday, February 22, 2021, 20:14 (1368 days ago) @ David Turell

That activity is blocked by a gene:

https://phys.org/news/2021-02-male-mosquitoes-humans.html

"Male mosquitoes won't bite you. For one thing, they cannot—males are hopelessly bad at finding humans and lack a specialized stylet to pierce your skin. But even if they could bite you, they would not want to. They refuse blood meals served to them in the lab through netting, even as their female counterparts engorge on what must appear to be a free lunch.

"It appears that both mosquito sexes share the same neurons and brain structures needed to find humans, but that this hardware is hidden in the male mosquito brain, locked behind a simple genetic switch. Mutate the right gene, the researchers discovered, and male mosquitoes begin buzzing toward human scents in search of a prize that they do not even want.

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"Basrur and colleagues began their work by examining a gene called fruitless, which is known to control courtship behavior in fruit flies. When they knocked out the analogous gene in male mosquitoes, these insects, like fruit flies, failed to mate effectively with females. But the scientists chose to investigate further, suspecting that the mutation might also impact male mosquitoes' desire for blood.

"When offered warm blood through a net, however, mutant males abstained just like non-mutant males, even as female mosquitoes partook. When exposed to body heat, females liked what they felt. Mutant males, true to their sex, remained unimpressed by the promise of a blood meal—suggesting the corrupted gene doesn't play a role in feeding behavior, per se.

"But when the scientists offered these mutant males a human arm, they suddenly swarmed. "This was a truly unexpected—and spectacular—finding," says Vosshall, who is the Robin Chemers Neustein Professor as well as an HHMI investigator. "We had never seen males interested in the scent of a human before."

"'Later tests confirmed that, while mutant male mosquitoes still lacked the desire to drink blood and the ability to sense body heat, turning off the fruitless gene had allowed their brains to process the unique smell of a live human—activating a repressed urge to seek out humans just like a female. "This suggests that male mosquitoes actually possess the neural circuits required to hunt humans," Basrur says. "Removing fruitless appears to reveal this latent behavior in males."

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"'For a long time, the assumption was that sex-specific behaviors came from sets of neurons entirely specific to that sex," Basrur says. "But recent work, including our study, has shown that both sexes often have the same neurons and that genetics controls how they are used.'"

Comment: A very interesting finding. Hopefully it wi lead to a solution for malaria transmission.