Deaf Mosquitoes Show No Interest in Courtship or Mating

A new study from the University of California, Santa Barbara, demonstrates that a single genetic alteration can effectively eliminate the mating drive of male mosquitoes, revealing the vital role of sound in mosquito courtship. Researchers found that when they disrupted the gene responsible for mosquitoes’ hearing, male mosquitoes entirely lost interest in mating. Published in Proceedings of the National Academy of Sciences, this research could inform new approaches to controlling disease-spreading mosquito populations, including species like Aedes aegypti, which transmit viruses affecting millions worldwide.

The importance of sound in mosquito courtship

In many mosquito species, male attraction to females relies on the sound of the females’ wingbeats, typically around 500 Hz. Male Aedes aegypti mosquitoes, upon detecting this frequency, adjust their own buzzing to approximately 800 Hz and increase this modulation when a female is nearby. This brief airborne encounter enables males to identify, pursue and mate with females. Once females mate, they typically do not mate again, while males continuously search for new partners.

Given the importance of hearing in mosquito courtship, the research team, led by Professor Craig Montell, hypothesized that eliminating auditory function might disrupt this behavior. The researchers focused on a sensory channel in mosquitoes known as TRPVa, which functions in the Johnston’s organ – a complex structure at the base of the antennae involved in multiple sensory processes, including hearing.

Gene knockout eliminates hearing and disrupts mating

Using CRISPR-Cas9, the researchers removed the trpVa gene in Aedes aegypti mosquitoes. With this alteration, the mosquitoes were entirely deaf, showing no neural activity in response to sound. Without auditory cues, the deaf male mosquitoes showed no inclination to engage in courtship or mating, even when kept with females for extended periods. In contrast, males with intact hearing responded quickly, mating frequently over just a few minutes.

Mating drive unaffected in females

Interestingly, deafness affected only the mating behavior of male mosquitoes. Deaf females remained capable of mating, though they did not initiate courtship. According to Montell, “The impact on the female is minimal, but the impact on the male is absolute,” indicating that auditory cues are critical for males to initiate mating behavior but less so for females. The team plans to investigate the sensory differences underlying this behavior in future studies.

“I think the reason why our major finding is so shocking is because, in most organisms, mating behavior is dependent on a combination of several sensory cues. The fact that taking away a single sense can completely abolish mating is fascinating.”

Emma Duge

Potential implications for mosquito population control

The discovery that sound alone drives male mosquito mating interest highlights the potential for new mosquito control strategies targeting mating behaviors in these disease-carrying species. Given the reliance of mosquitoes like Aedes aegypti on auditory cues for reproduction, disrupting this sense could help manage mosquito populations and reduce the spread of mosquito-borne diseases.

Reference: Wang Y, Thakur D, Duge E, et al. Deafness due to loss of a TRPV channel eliminates mating behavior in Aedes aegypti males. Proc Natl Acad Sci USA. 2024;121(47):e2404324121. doi: 10.1073/pnas.2404324121

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