Mosquito mating ritual sounds can help make drones quieter

Researchers at Johns Hopkins University have discovered that mosquitoes flap wings not only to fly, but also to produce noise and to direct that sound toward a possible companion. These findings, says a news release by JHU, about mosquito wings’ aerodynamics could help create quieter drones.

A team from the Whiting School of Engineering of Johns Hopkins University explains in a research paper co-authored with University of North Carolina at Chapel Hill biology professor Tyson L. Hedrick and published in Bioinspiration and Biomimetics, the acoustics and aerodynamics of the mosquito mating ritual via computer modeling. The team includes associate research professor Jung-Hee Seo and mechanical engineering professor Rajat Mittal, who is an expert in computational fluid dynamics.

“The same wings that are producing sound are also essential for them to fly,” said Mittal. “They somehow have to do both at the same time. And they’re effective at it. That’s why we have so much malaria and other mosquito borne diseases.”

The research by the team reveals that “everything about mosquitoes seems perfectly adapted for accomplishing this sound-based communication.”

The paper says, “Thus, understanding the strategies and adaptations employed by insects such as mosquitoes to control their aeroacoustic noise could eventually provide insights into the development of quiet drones and other bioinspired micro-aerial vehicles.”

Mittal said that as well as developing quieter propellers for drones, the research’s conclusions will possibly help understand how sound can be exploited to interrupt the mating ritual, likely resulting in non-toxic ways to disrupt breeding and reduce mosquito populations.

“We continue to pursue that side of the research,” Mittal further said. “At the right frequency the mosquitoes have a hard time flying and can’t complete their mating ritual.”

The male mosquito makes a high-frequency buzzing sound in an attempt to connect with the low-frequency hum of a female mosquito. The team found that to do so, the mosquito has to flap its slender, long wings at high frequencies while rotating them fast at the end of each blow.

Mittal said that unlike other flying insects of their size, mosquitoes have modified their anatomy and flight physiology to solve the “complex multifactorial problem” of attempting to fly and flirt simultaneously.

The paper reports, “The wing tones as well as the aerodynamic forces for flight are highly directional and mosquitoes need to simultaneously control both for the successful completion of a mate-chase.”

According to the research, the fast movement of the wings “generate additional lift force” to help mosquitoes stay aloft. But this very movement also assists in pointing the “wing tone” toward a forward direction, which is important for going after possible companion.

Mittal explained, “If I’m talking to you and I turn my back, you’ll have a hard time hearing me. They have to be able to direct their sounds properly.”

The fast rotation and truncated range, or amplitude, is much quicker and shorter compared to winged insects of the similar size, such as fruit flies. The paper says that is the reason mosquitoes, unlike fruit flies, have a “wing tone buzz” that is “particularly annoying to humans.”

Mittal concluded, “[the] long and slender wing is perfect for making sounds. Fruit flies, which are similar in size to mosquitoes, have short and stubby wings. Furthermore, mosquitoes are flapping at much higher frequencies than fruit flies. There is a reason for this. Higher frequencies are better at producing sounds.”

Image credit - Rajat Mittal [via EurekAlert! and the American Association for the Advancement of Science (AAAS).  https://www.eurekalert.org/multimedia/pub/216315.php]