Scientists have revealed that giving mosquitoes diet drugs prevents them from biting humans and spreading disease.
The scientists who carried out the study found that female mosquitoes, which transmit the microbes that kill millions of people every year, lose interest in human blood if their appetites are suppressed with the chemicals.
The study, which is still in its early stages, was published in the journal Cell. It showed that by manipulating the hormones which make mosquitoes feel full, the insects’ desire for blood can be satiated.
“We were impressed and amazed that drugs designed to affect human appetite worked perfectly to suppress mosquito appetite,” study author Leslie Vosshall said in a statement.
The scientists carried out experiments on female Aedes aegypti mosquitoes, which require human blood for the proteins they need to produce eggs. This species is responsible for spreading yellow fever, dengue fever and Zika virus.
The researchers noted, however, that once these mosquitoes fed on human blood and become bloated, their attraction to humans declines for several days.
“It’s like the ultimate Thanskgiving dinner,” said Laura Duvall, a study author.
The team of researchers from Rockefeller University in New York City targeted their research on neuropeptide Y (NPY) receptors, which regulate food intake in humans.
The scientists gave the mosquitoes a saline solution containing the drugs developed by the pharmaceutical industry to activate and inhibit these receptors in humans, and found the insects’ appetite and attraction to humans dropped sharply.
They measured this by hanging up a nylon stocking previously worn by Duvall for long enough for body odors to be absorbed, and observing whether mosquitoes flew toward it. They also tested the mosquitoes on mice to see whether they would bite a live host, Duvall told CNN.
The scientists tested all 49 NPY receptors in mosquitoes with the drugs to determine which was responsible for controlling appetite. They also conducted extensive testing on thousands of compounds to determine which could target mosquitoes directly rather than also having an impact on humans.
James Logan, head of the department for disease control at the London School of Hygiene and Tropical Medicine, described the discovery of this potential new technology as “exciting” and “intriguing.”
“One of the biggest problems we have with the control of mosquito-borne diseases is resistance of mosquitoes to insecticides,” he told CNN.
“A compound with a novel mode of action that prevents mosquito feeding could be useful if it is effective, logistically feasible and sustainable under field conditions.”
Logan warned, however, that “there is a lot of work to be done before this could be deployed in the field.”
Paul Reiter, a former professor of medical entomology at the Pasteur Institute, also told CNN that the proposed method was a “fascinating idea” and “very plausible.”
He noted that new ideas on how to combat mosquitoes are desperately needed, as scientists are currently “useless” at stopping the spread of conditions such as dengue fever. He noted, however, that methods of transferring the drugs to the mosquitoes are “not too easy,” but suggested that “sugar baits” could be a solution.
Leo Braack, senior vector control specialist from the Malaria Consortium, said that these findings “represent a new direction for intervening in contact between disease-carrying mosquitoes and their human hosts” and “humanity urgently needs new tools to stem the tide of rising mosquito-borne infections.”
Braack added that “much remains to be clarified and requires further research.
“How, for example, do such mosquitoes with reduced feeding capacity compete with other wild individuals in producing eggs and producing offspring … which requires frequent bloodmeals?”
The study scientists also noted that while the initial research could provide a “novel approach to control infectious disease transmission,” limitations remained.
While the researchers know which drugs activate the mosquitoes’ NPY receptors in the lab, they are uncertain which naturally occurring neuropeptides do in the wild, Duvall said. Researchers have nevertheless deciphered a list of nine potential neuropeptides.
The scientists must also carry out further research to determine where the receptors are produced in mosquitoes and how they may be naturally activated.
A technique would also need to be developed in order to successfully transfer the drugs into mosquitoes in the wild.