If human relationships are often complex, among mosquitoes, seduction comes from a simple beating of their wings. The males Aedes aegyptifearsome vectors of diseases such as dengue and zika, detect females by listening to their characteristic buzzing, due to the rapid beating of their wings.
However, a recent study from the University of California, Santa Barbara published in PNAS reveals that a deaf mosquito loses interest in mating. This discovery could open the way to new methods of combating these insects.
Deafness: a simple modified gene and the libido disappears
To study the role of hearing in mosquito behavior, Professor Craig Montell’s team used CRISPR technology to delete a single gene, trpVa, in males Aedes aegyptithus making them totally deaf.
The hidden beauty of insects
This gene controls a sensory channel present in their Johnston’s organ, located at the base of the antennae, essential for detecting the vibrations of females’ wingbeats. The result is surprising: deprived of their hearing capacity, these males showed no sign of interest towards females.
“You can leave them together for days, they won’t mate.”comments Craig Montell.
When sound makes all the difference
Normally, among Aedes aegyptithe mating takes place like a sound ballet. Females flap their wings at a frequency of 500 Hz, triggering a response in males, who modulate their own buzzing at 800 Hz to attract them.
This aerial encounter lasts only a few seconds, before each partner resumes their route. But, without this specific “music”, males no longer have any interest in females.
The experiments of Montell and his team show that sound plays an essential role, much more than a simple detail, in arousing desire in these insects. When they artificially broadcast the sound of female wings, hearing males responded immediately, while deaf males remained unmoved.
Curiously, this hearing loss had little effect on the females, who still remained willing to mate.
A way to limit epidemics?
Every year, mosquito-borne diseases infect hundreds of millions of people. One way to curb their proliferation is based on the Sterile Insect Technique (SIT), where sterile males are released in large numbers to mate with females, thus preventing reproduction.
However, this method only works if sterile males succeed in seducing females, which is often a challenge facing wild males.
The study on the trpVa gene opens up interesting perspectives. By deafening some males or changing their hearing behavior, it might be possible to make them more competitive and increase the effectiveness of SIT. According to Craig Montell, targeting the biology of sound in mosquitoes could help limit their reproduction and, ultimately, their role in disease transmission.
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