Silencing mosquito 'mating song' could help reduce diseases

In the U.S., mosquitoes are known to spread West Nile virus, Eastern equine encephalitis, and Zika, among other diseases.

Researchers at the University of Iowa and Nagoya University in Japan say the mosquito's "mating song" may be the key to reducing their reproduction, and therefore the diseases they are able to spread among humans.

Researchers found a gene that controls the antenna movements of female fruit flies, which is how they detect the sound produced by prospective mates, and they say the same gene exists in mosquitoes. Crucially, the gene can be silenced.

“Mosquitoes actually have a very similar mechanism to fruit flies of a type of active tuning, which could have implications for deterring the spread of so many diseases,” Daniel Eberl, professor in the Department of Biology at Iowa and the corresponding author of the study published in eNeuro, said in a statement. “So, understanding how fruit flies and mosquitoes not only mate but also how they hear could have important considerations for human health.”

Mosquitoes are well known for spreading diseases among humans and other mammals, some of which can be deadly. In the U.S., mosquitoes are known to spread West Nile virus, Eastern equine encephalitis, and Zika, among other diseases.

The researchers used tiny microphones to detect the sound produce when a male fruit fly beats its wings. Those vibrations are picked up by the female fruit fly's antennae letting her know a prospective mate is nearby.

Not every "courtship song" is the same, however, and although scientists have known that female fruit flies "tune" their antennae to pick up the frequencies produced by compatible species, they didn't know exactly how.

“I think a key point for us is that the songs that they sing are a little bit different in closely related species,” Eberl said. “The spacing between the pulses is distinct for each species. And that's why it's important, because they want to mate with a mate from their own species. So, the song helps them give that recognition of same species.”

Researchers studied the hearing in female Drosophila melanogaster fruit flies, looking in particular at the fly's Johnston’s organ. They found and studied a pathway called a potassium ion channel, which activates neurons involved in the fly's "hearing."

Further investigation revealed a gene, called Shal, functions as a sort of gatekeeper for the ion channel, dictating when outside sounds are converted to electrical signals and passed between neurons. The chain of events managed by the Shal gene seemed essential for the fly to hear, so researchers tried turning it off.

“Without the Shal gene, it loses that ability to tune,” said Eli Gregory, an undergraduate human physiology major who carried out the gene-canceling experiments. “The female loses its ability to tune that antenna to that frequency. And so, you get this lower response in mating from that female.”

Researchers believe the procedure could have similar effects on mosquitoes.

“We could conceivably knock out that gene or that potassium channel and prevent mosquitoes from being able to mate as effectively as they do, which could mean fewer mosquitoes; therefore, fewer problems for human health,” Eberl said.

The research was funded by the U.S. National Science Foundation, University of Iowa Office for Undergraduate Research, JSPS Invitational Fellowships for Research in Japan, Nagoya University, and the Japan Science and Technology Agency FOREST program funded the research.

Reporting by TMX

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