- Mosquito antennae are complex structures that transduce sound into electrical signals, which are then zapped to the brain.
- Different mosquito species have antennae structured to pick up different sounds, such as frog calls or the sound of female wingbeats.
- In the future, the antennae of what we think of as pests could inspire both soundproofing and sound-detecting materials.
Mosquitoes. We swat them, spray them, and otherwise try to get rid of them by any means necessary. But it turns out that these insects—which have been little more than insufferable pest to humanity for most of our existence—might actually be useful for something.
Hypersensitive mosquito antennae are able to pick up specific signals, even through the buzz of their noisy wingbeats, and a team of researchers hoped that finding out how they do it could inspire soundproofing materials and super-sensors. The interdisciplinary team, led by Pablo Zavattieri and Ximena Bernal of Purdue University, zoomed in on the antennae of two mosquito species using microscopy and CT scanning. What they saw were complex structures built to optimize sound detection.
Aedes aegypti and Uranotaenia lowii are mosquito species which use the acute hearing capabilities of their antennae for different purposes. Ae. aegypti males seek out potential mates by listening for female wingbeats, and U. lowii females (which need a blood meal to lay eggs) hunt for frogs to prey on by listening for their calls.
“Structural variation, as well as material properties in the antennae, are critical to modulating the vibrational response characteristic of the antenna and consequently, to determine hearing traits used for different biological purposes,” the team said in a study recently published in Acta Biomaterialia.
Mosquito antennae have a main antennal shaft, or flagellum, and a secondary segment that contains the Johnston’s Organ—thought to be the most complex known insect organ capable of responding to mechanical stimuli. The main antennal shaft is made of smaller segments, each covered in long, thin sensory hairs called fibrillae. When a sound hits the flagellum and these hairs, both vibrate, so the mosquito hears different frequencies. In the secondary segment of the antenna, physical vibrations from the flagellum are transduced into electrical signals in the Johnston’s Organ, and these signals are then zapped to the brain.
How mosquitoes were able to tune in to certain sounds while tuning out the sound of their own flying (and any other background noise) has never been investigated before now. But using computational models based on the antennae of live specimens, Zavattieri and Bernal’s team were able to analyze the segments and hairs of the antenna models and then test for which sounds these structures were most receptive to.
Vibration in Ae. aegypti male antennae turned out to be most prominent when female wingbeats were played, even with the sounds of male wingbeats in the way. Ur. lowii male antennae didn’t respond much, since they chase females by following their pheromones. Similarly, Ur. lowii female antennae vibrated most when frog calls were played (they especially crave barking tree frogs). For Ae. aegypti females, the volume on these calls had to be ramped up for them to have any reaction at all, since they primarily use their sense of smell to find unknowing animals for their next meal.
While the entire range of frequencies that mosquitoes are capable of detecting is still unknown, Zavattieri thinks that this investigation could inform the next generation of noise-cancelling devices and soundproofing materials. It could enable, for example, the development of sensors that can pick out faint noises amid the roar of city traffic, or hear sounds of distress that would otherwise be drowned out by natural disasters.
“In times of crisis—such as earthquakes or other disasters—these sensors become invaluable, swiftly detecting faint signals of distress and guiding rescue efforts to those in need,” he said in a recent press release.
Antenna models are now being 3D-printed in various sizes, using different materials to see which will work best for different applications. Keep an ear—or an antenna—out for them in the future.
Elizabeth Rayne is a creature who writes. Her work has appeared in Ars Technica, SYFY WIRE, Space.com, Live Science, Den of Geek, Forbidden Futures and Collective Tales. She lurks right outside New York City with her parrot, Lestat. When not writing, she can be found drawing, playing the piano or shapeshifting.
