Switch off one gene and a male mosquito stops hearing females

Male Aedes aegypti mosquitoes mutated at a single gene, called fruitless, did not respond to any of the female wingbeat tones researchers played to them, and the ear signals they produced were about one-sixth the size of those from normal males. The work, from Nagoya University in Japan with a collaborator at the University of Iowa, appeared in PLOS Biology on October 27, 2026.

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Aedes aegypti is the mosquito behind dengue, Zika and yellow fever transmission in much of the tropics. Because only females bite, any control method that keeps males from finding mates is of direct interest. The new paper pins a large part of that mate-finding skill on one gene.

Mutant males at dusk

In normal Aedes aegypti, males are drawn to the flight sound of females, while females show no such pull. The Nagoya team, led in the laboratory by postdoctoral researcher Yumin Loh with assistant professor Matthew Su and professor Azusa Kamikouchi, disrupted the male-specific version of fruitless, known as FruM, and tested what happened. The Institute of Transformative Bio-Molecules at Nagoya University, where they work, described the result in its release on the study: the mutant males could not locate females.

Behavior changed visibly at dusk, when normal males gather. Normal males flew near the center of the cage, while mutant males stayed along the edges, the same pattern seen in females. Tracking software logged far fewer fly-by encounters among the mutants than among normal males, a gap the authors report as statistically significant (p = 3.58 x 10^-6).

The mutants still beat their wings at about the same rate as normal males, so the problem was not the signal they send but how they take in the one females send.

One-sixth of the ear response

The team played tones from 350 to 850 hertz, a band that includes the mean female wingbeat of 470 hertz. Mutant males were not attracted to any of them. Normal males bent their abdomens in response to sound, including at 470 hertz, and the mutants never did.

The ear itself, a structure on the antenna called Johnston’s organ, explains much of this. According to the PLOS Biology paper, antennal nerve responses in normal males were roughly six times greater than those in mutant males and in females. Normal male ears also showed self-sustained oscillations, a built-in amplification of female flight sound, when treated with tetanus toxin or cAMP. Mutant males did not.

The authors also found structural changes. Mutant males had fewer of the nerve terminals typical of males, lacked one terminal type entirely and gained a type normally found in females.

That combination is why the claim needs a careful reading. The paper notes that mutant ears still show active hearing, so the central processing of sound is not ruled out as a factor. What the gene switches off is the male-specific machinery that amplifies and tunes in the sound of a female, leaving the mutant functionally unable to follow it.

Dlc90F and the genes FruM holds down

The researchers compared gene activity in the antennal base of mutant and normal males and found 1,252 genes more active and 994 less active in the mutants. One of them, a dynein gene named Dlc90F, is normally more active in females and became active in mutant males as well. The authors propose that FruM represses it in males.

They tested that idea directly. Binding assays showed that the zinc-finger portion of the FruM protein attaches to two sites in the Dlc90F enhancer, and a motif resembling the fruit fly FruM binding site, with 7 of 10 bases identical, was enriched among genes the protein appears to hold down. In the paper’s framing, FruM works as a master regulator of male hearing, acting at the first stage of the process, in the ear.

From a laboratory strain to mosquito control

The authors propose fruitless as a target for genetic control strategies that exploit the sex-determination pathway. The Nagoya release says that interfering with the gene and the genes it controls might disrupt the earliest stage of reproduction.

The stakes are the diseases themselves. The World Health Organization describes dengue as transmitted by Aedes mosquitoes, and the Centers for Disease Control and Prevention lists Zika among the viruses these mosquitoes carry. The CDC’s Aedes profile covers where the insect breeds and why it is hard to control with sprays alone.

Two limits apply. The mating failure is inferred from the loss of attraction to sound and from earlier reports, not tested directly in this paper. And the work was done on laboratory mosquitoes aged 5 to 7 days, virgin and unfed. Whether release of fruitless-disrupted males could suppress a wild population is not something the study attempts to show, and that question is the obvious next one for the Nagoya group.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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