Mosquitoes make a lot of noise and are very annoying, but why is this? The answer is complicated and is often a mystery. There are several theories. They include the Flight tones, Detection range, and Male-female acoustic interactions.
Flight tones
Mosquitoes have a unique ability to communicate with each other using their flight tones. Male mosquitoes change their flight tones throughout the day. At dusk, they beat their wings 1.5 times faster than females. They also restrict this flight tone adjustment to specific times of the day, such as during swarming. This acoustic communication allows male mosquitoes to find females more efficiently.
These flight tones can be used to differentiate between male and female mosquitoes, which is particularly useful in the case of swarming. The frequencies were measured by recording and analyzing wingbeat tracks from male and female mosquitoes. The wingbeat frequency of males was correlated with its spatial location.
Male-female auditory interactions
Mosquitoes’ loud songs are a result of bidirectional auditory interactions between male and female individuals. In pairs, male and female mosquitoes emit a common fundamental flight tone, matching at a frequency of 1200 hertz, a factor that exceeds the known upper limit of hearing in mosquitoes. This finding suggests that mosquitoes’ auditory systems differ between sexes, and the shared tone frequencies are important for mating.
The male mosquitoes have special auditory organs located on their flagellar wings, which act as amplifiers for female wingbeat sounds. These organs are thought to function as a potential target for vector control.
Detection range
Unlike humans, mosquitoes can detect human presence in an area by sight. They use their sight to identify suitable hosts, and are attracted to humans by CO2 emissions. In areas without sunlight, mosquitoes can detect thermal heat from their host within a one-meter range.
Researchers from the University of Washington found that certain species of mosquitoes respond to different colors, and will fly toward certain colors, but ignore others. They believe this could help explain how mosquitoes find humans. Human skin has a strong red-orange “signal” that mosquitoes use to find their hosts.
Using a simple reproducible system, they were able to compare the responses to various compounds in full-field and semi-field environments. This knowledge can help us develop better malaria control strategies, and it contributes to our understanding of olfactory behaviour in mosquitoes. In addition, the approach could be extended to other arthropods.
Male-female acoustic interactions
The sound produced by mosquitoes is the result of male-female acoustic interaction. When a male mosquito hears the sound of a female mosquito beating her wings, he generates a phantom tone in response. This noise is produced continuously and can be heard as far as ten feet away.
Male-female acoustics interact to influence mating behavior. When males fly in a swarm, the females hear the sound of the males’ flight. This sounds much louder than the females’ swarming sounds. This demonstrates that the sound is a male attractant, but odor plays no role in the attraction.
The researchers collected acoustic data at a few sites, including the Stanford University campus in Palo Alto, California, and the Centre ValBio in Ranomafana, Madagascar. They collected field acoustics by tracking mosquitoes while they flew in free flight. They also collected live recordings by trapping mosquitoes in a Ziploc bag. The primary microphone is placed against the Ziploc bag, but this is not a perfect solution, since the Ziploc bag has a brushed surface that introduces noise.
Female acoustic interactions
In order to investigate the acoustic interactions of mosquito swarms, researchers have conducted experiments with single-sex swarms. They used artificial flight tone stimuli to mimic the alternating playback of female baseline swarm tone frequencies and mating interaction tones. They sampled audio spectrograms at intervals of 60 s to measure fundamental flight tone frequencies and amplitudes. This information can be used to design effective reproductive control strategies.
The amplitude of flight tones varied with distance and direction. The tones were loudest ahead and behind the mosquitoes and quieter to the right and left. The tones exhibited quadratic phase coupling. The data were analyzed using Raven Pro software and spectral analysis to identify the fundamental flight tone frequencies.
