Scientists have genetically engineered mosquitoes’ sense of smell, altering how they respond to odors including the scent of humans and the insect repellant DEET.
In a new study, Rockefeller University’s Leslie Vosshall, Ph.D., and her colleagues show that mosquitoes can be genetically modified successfully, plus point to reasons why the insects are so attracted to humans—and potentially, how to block that attraction.
Dr. Vosshall and her colleagues used zinc-finger nucleases to specifically mutate their target, the gene orco, in mosquito embryos. "We knew this gene was important for flies to be able to respond to the odors they respond to," she said in a statement. "And we had some hints that mosquitoes interact with smells in their environment, so it was a good bet that something would interact with orco in mosquitoes."
Once the embryos had matured, engineered mosquitoes showed diminished activity in neurons linked to odor-sensing. Further, given a choice between humans and guinea pigs, the mosquitoes with orco mutations showed reduced preference for the smell of the former.
"By disrupting a single gene, we can fundamentally confuse the mosquito from its task of seeking humans," Dr. Vosshall said.
Additionally, mosquitoes with orco mutations responded differently to DEET. That the genetically engineered insects were attracted equally to human arms with or without DEET suggested they were unable to smell the repellant, the scientists said.
Going forward, Dr. Vosshall and her colleagues intend to figure out how the orco protein interacts with the mosquitoes' odorant receptors. “We want to know what it is about these mosquitoes that makes them so specialized for humans," she said. "And if we can also provide insights into how existing repellants are working, then we can start having some ideas about what a next-generation repellant would look like."
"Orco mutant mosquitoes lose strong preference for humans and are not repelled by volatile DEET," appeared online in Nature May 29.