The short version
- Male yellow fever mosquitoes find females by ear, tuning in to a wingbeat of about 450 Hz against their own 750 Hz.
- When Nagoya researchers knocked out a gene called fruitless, the males’ ears sent signals about one-sixth as strong and the males ignored female-pitched tones.
- The researchers say the finding could one day help mosquito control, but nothing like that has been tested.
A male Aedes aegypti, the yellow fever mosquito, finds a mate by sound. Females beat their wings at about 450 Hz and males at about 750 Hz, and the male’s ears are most sensitive in the female’s range. A team led by Azusa Kamikouchi and Matthew Su at Nagoya University, with Daniel Eberl at the University of Iowa, reported in PLOS Biology on October 27 that this tuning depends on a single gene, fruitless.
Males bred without the male form of the gene flew like females and stopped gathering at dusk. Played tones from 350 to 850 Hz, normal males flew toward the female range, and the mutants flew toward none of them. Their ears were tuned higher than normal males’, and the same tone produced a nerve response about one-sixth as large. A rhythmic self-sustained vibration that normal male ears produce on their own was missing in every mutant tested. The mutants’ ears also had a rearranged network of efferent neurons, the nerves that carry signals from brain to ear. Mosquitoes are the only insects known to have them.
The work was done in lab colonies of one species. The mutant ears still showed active hearing, so the authors say part of the deafness to females may lie in the brain, not the ear. They raise mosquito control as a possible use. No one has tested it.
