Researchers found the yellow fever mosquito had a genetic "tweak" that makes it more wary of the smell of human blood.
The gene AaegOr4, which is responsible for this sensitivity, was found to be more prevalent in domestic "human loving" Mosquitos than in the forest breed, Princeton University reported. The findings provide rare insight into the genetic changes that cause behaviors to develop in the first place.
"The more we know about the genes and compounds that help mosquitoes target us, the better chance we have of manipulating their response to our odor" McBride said,
To make their findings the researchers put foreign and domestic mosquitoes in a large cage and allowed them to bite either a guinea pig or a researcher's arm. The mosquitoes were then propmted to chooses between streams of air that passed over a human arm or a guinea pig's body. Later they were also given the option to choose between a nylon sleeve that had been in contact with a human or a guinea pig.
In all three cases the domestic form of the yellow fever mosquito showed a strong preference for the human scent while the forest form tended to chooses the guinea pig. To find out why, the researchers looked at differences in the populations' antennae, which allow the insects to smell. They interbred forest and domestic species to create a hybrid mosquito, the genomes of which were shuffled that researchers were able to look at only the genes related to behavior. The team found 14 genetic differences between the human and guinea pig preferring hybrids, two of which were the odorant receptors Or4 and Or103.
The scientists implanted the gene into fruit-fly neurons and found they exhibited a burst of activity when exposed to sulcatone (a compound prevalent in the human odor) but not when exposed to guinea pig odors.
The finding could help researchers come up with better ways to prevent conditions such as Yellow Fever by targeting mosquitoes' sensitivity to humans and also provides insight into how the mosquito developed into a "human-biting specialist."
"At least one of the things that happened is a retuning of the ways odors are detected by the antennae," Mcbride said. "We don't yet know whether there are also differences in how odor information is interpreted by the brain."
The findings were published in a recent edition of the journal Nature.
