scholarly journals Mosquito sound communication: are male swarms loud enough to attract females?

2021 ◽  
Vol 18 (177) ◽  
Author(s):  
Lionel Feugère ◽  
Gabriella Gibson ◽  
Nicholas C. Manoukis ◽  
Olivier Roux
Keyword(s):  
Long Range ◽  
Particle Velocity ◽  
Sound Source ◽  
Large Male ◽  
Anopheles Coluzzii ◽  
Source Power ◽  
Sound Communication ◽  
Sound Levels ◽  
Sound Sensitivity ◽  
Species Specific

Given the unsurpassed sound sensitivity of mosquitoes among arthropods and the sound source power required for long-range hearing, we investigated the distance over which female mosquitoes detect species-specific cues in the sound of station-keeping mating swarms. A common misunderstanding, that mosquitoes cannot hear at long range because their hearing organs are ‘particle-velocity’ receptors, has clouded the fact that particle velocity is an intrinsic component of sound whatever the distance to the sound source. We exposed free-flying Anopheles coluzzii females to pre-recorded sounds of male An. coluzzii and An. gambiae s.s. swarms over a range of natural sound levels. Sound levels tested were related to equivalent distances between the female and the swarm for a given number of males, enabling us to infer distances over which females might hear large male swarms. We show that females do not respond to swarm sound up to 48 dB sound pressure level (SPL) and that louder SPLs are not ecologically relevant for a swarm. Considering that swarms are the only mosquito sound source that would be loud enough to be heard at long range, we conclude that inter-mosquito acoustic communication is restricted to close-range pair interactions. We also showed that the sensitivity to sound in free-flying males is much enhanced compared to that of tethered ones.

scholarly journals Mosquito sound communication: assessment of ecologically relevant ranges

2020 ◽  
Author(s):  
Lionel Feugère ◽  
Gabriella Gibson ◽  
Nicholas C. Manoukis ◽  
Olivier Roux
Keyword(s):  
Large Male ◽  
Sound Level ◽  
Anopheles Coluzzii ◽  
Source Power ◽  
Sound Communication ◽  
Communication Assessment ◽  
Sound Levels ◽  
Close Range ◽  
Sound Sensitivity ◽  
Species Specific

AbstractGiven the unsurpassed sound sensitivity of mosquitoes among arthropods and the sound-source power required for long-range hearing, we investigated the distance over which female mosquitoes might identify species-specific cues in the sound of mating swarms. We exposed free-flying Anopheles coluzzii females to pre-recorded sounds of male An. coluzzii and closely related An. gambiae s.s. swarms over a range of natural sound-levels, based on a reference recording. Sound-levels tested were related to equivalent distances between the female and the swarm for a given number of males, enabling us to infer distances over which females can hear large male swarms. We show that even for the loudest swarms, a female hears an individual male at the edge of the swarm sooner than she would hear the swarm as a whole, due to the exponential increase in sound level at close-range. We conclude that inter-mosquito acoustic communication is restricted to close-range pair interactions.

scholarly journals Behavioural measurements of hearing-sensitivity in swarming Anopheles coluzzii mosquitoes reveal an unprecedentedly low threshold

2021 ◽  
Author(s):  
Lionel Feugère ◽  
Olivier Roux ◽  
Gabriella Gibson
Keyword(s):  
Particle Velocity ◽  
Hearing Threshold ◽  
Dynamic Responses ◽  
Anopheles Coluzzii ◽  
Single Female ◽  
Flight Pattern ◽  
Constant Frequency ◽  
Hearing Sensitivity ◽  
Natural Behaviour ◽  
Sound Levels

AbstractBackgroundMale and female mosquitoes of many species mate in swarms consisting of males and uninseminated females; males form station-keeping swarms and mating chases ensue as soon as a male detects the flight tones of a female. The auditory organs of mosquitoes have been reported to be the most sensitive among arthropods, enabling them to track their flying mate by the sound of the female’s flight tones during mating chases. Previous studies on hearing thresholds have mainly used electrophysiological methods, which unfortunately limit the natural behaviour of the mosquitoes. This study explores male auditory behavioural sensitivity to female flight tones.MethodsWe developed a behavioural method for measuring hearing sensitivity in swarming male mosquitoes. Free-flying male Anopheles coluzzii mosquitoes were released in a large arena (∼2 m high × 2 m × 1 m) with a visually conspicuous object on the ground that stimulates swarming behaviour consisting of elliptical flight pattern over the object. Males were exposed to a range of natural and synthetic played-back sounds of female flight emanating from a speaker located at the same height as the swarm centre and 0.9 m away from it. We monitored the responses of males to female sound by recording the flight-tone and flight-dynamic responses of males. Calibrated sound-levels were measured at the swarm centre; the changing distances between the speaker and the flying males as well as other measurement uncertainties were taken into account to estimate the sound levels that males were effectively exposed to.ResultsWe show that the mean male behavioural threshold of particle-velocity hearing lies between 13-20 dB SVL (95%-CI). A conservative estimate of 20 dB SVL (i.e., less than a particle velocity of 0.5 µm/s) is already 12 to 26 dB less than most of the published electrophysiological measurements on Johnston’s organ sensilla. Our results confirm, under laboratory conditions, the high behavioural hearing-sensitivity of swarming mosquitoes recently found with swarming Aedes communis in the field, and suggest a hearing threshold at least two times lower than that of published results (26 dB SVL or 1 µm/s particle-velocity). In addition, we established that 1) the first harmonic of Anopheles coluzzii female flight sound is sufficient for males to detect her presence, 2) males respond with a greater amplitude to single-female sounds than to group-female sounds and 3) males respond to the playback of single-female sound as much as to pure-sound at a constant frequency and amplitude.

scholarly journals A Drosophila female pheromone elicits species-specific long-range attraction via an olfactory channel with dual specificity for sex and food

BMC Biology ◽  
2017 ◽  
Vol 15 (1) ◽  
Author(s):  
Sebastien Lebreton ◽  
Felipe Borrero-Echeverry ◽  
Francisco Gonzalez ◽  
Marit Solum ◽  
Erika A. Wallin ◽  
...  
Keyword(s):  
Long Range ◽  
Female Pheromone ◽  
Dual Specificity ◽  
Species Specific

scholarly journals Rat primary auditory cortex is tuned exclusively to the contralateral hemifield

2013 ◽  
Vol 110 (9) ◽  
pp. 2140-2151 ◽  
Author(s):  
Justin D. Yao ◽  
Peter Bremen ◽  
John C. Middlebrooks
Keyword(s):  
Auditory Cortex ◽  
Sound Source ◽  
Cortical Neurons ◽  
Free Field ◽  
Primary Auditory Cortex ◽  
Homogeneous Population ◽  
Spatial Sensitivity ◽  
Spatial Tuning ◽  
Sound Levels

The rat is a widely used species for study of the auditory system. Psychophysical results from rats have shown an inability to discriminate sound source locations within a lateral hemifield, despite showing fairly sharp near-midline acuity. We tested the hypothesis that those characteristics of the rat's sound localization psychophysics are evident in the characteristics of spatial sensitivity of its cortical neurons. In addition, we sought quantitative descriptions of in vivo spatial sensitivity of cortical neurons that would support development of an in vitro experimental model to study cortical mechanisms of spatial hearing. We assessed the spatial sensitivity of single- and multiple-neuron responses in the primary auditory cortex (A1) of urethane-anesthetized rats. Free-field noise bursts were varied throughout 360° of azimuth in the horizontal plane at sound levels from 10 to 40 dB above neural thresholds. All neurons encountered in A1 displayed contralateral-hemifield spatial tuning in that they responded strongly to contralateral sound source locations, their responses cut off sharply for locations near the frontal midline, and they showed weak or no responses to ipsilateral sources. Spatial tuning was quite stable across a 30-dB range of sound levels. Consistent with rat psychophysical results, a linear discriminator analysis of spike counts exhibited high spatial acuity for near-midline sounds and poor discrimination for off-midline locations. Hemifield spatial tuning is the most common pattern across all mammals tested previously. The homogeneous population of neurons in rat area A1 will make an excellent system for study of the mechanisms underlying that pattern.

scholarly journals Neural population encoding and decoding of sound source location across sound level in the rabbit inferior colliculus

2016 ◽  
Vol 115 (1) ◽  
pp. 193-207 ◽  
Author(s):  
Mitchell L. Day ◽  
Bertrand Delgutte
Keyword(s):  
Inferior Colliculus ◽  
Sound Source ◽  
Auditory Pathway ◽  
Relevant Information ◽  
Sound Level ◽  
Neural Population ◽  
Linear Transformations ◽  
Tuning Curves ◽  
Azimuthal Position ◽  
Sound Levels

At lower levels of sensory processing, the representation of a stimulus feature in the response of a neural population can vary in complex ways across different stimulus intensities, potentially changing the amount of feature-relevant information in the response. How higher-level neural circuits could implement feature decoding computations that compensate for these intensity-dependent variations remains unclear. Here we focused on neurons in the inferior colliculus (IC) of unanesthetized rabbits, whose firing rates are sensitive to both the azimuthal position of a sound source and its sound level. We found that the azimuth tuning curves of an IC neuron at different sound levels tend to be linear transformations of each other. These transformations could either increase or decrease the mutual information between source azimuth and spike count with increasing level for individual neurons, yet population azimuthal information remained constant across the absolute sound levels tested (35, 50, and 65 dB SPL), as inferred from the performance of a maximum-likelihood neural population decoder. We harnessed evidence of level-dependent linear transformations to reduce the number of free parameters in the creation of an accurate cross-level population decoder of azimuth. Interestingly, this decoder predicts monotonic azimuth tuning curves, broadly sensitive to contralateral azimuths, in neurons at higher levels in the auditory pathway.

scholarly journals Insect Repellents Mediate Species-Specific Olfactory Behaviors in Mosquitoes

2020 ◽  
Author(s):  
Ali Afify ◽  
Christopher John Potter
Keyword(s):  
Mosquito Species ◽  
Behavioral Responses ◽  
Anopheles Coluzzii ◽  
Olfactory Neurons ◽  
Insect Repellents ◽  
Olfactory Responses ◽  
Behavioral Studies ◽  
Lemongrass Oil ◽  
Mosquito Repellents ◽  
Species Specific

Abstract Background: The species-specific mode of action for DEET and many other mosquito repellents is often unclear. Confusion may arise for many reasons. First, the response of a single mosquito species is often used to represent all mosquito species. Second, behavioral studies usually test the effect of repellents on mosquito attraction towards human odorants, rather than their direct repulsive effect on mosquitoes. Third, the mosquito sensory neuron responses towards repellents are often not directly examined. Methods: Here, we used a close proximity response assay to test the direct repulsive effect of six mosquito repellents on Anopheles coluzzii , Aedes aegypti , and Culex quinquefasciatus mosquitoes. Additionally, we used this behavioral assay and calcium imaging recordings of antennae to test the response of An. coluzzii mosquitoes towards two human odorants (1-octen-3-ol and benzaldehyde) at different concentrations, and mixtures of the repellents lemongrass oil and p-menthane-3,8-diol (PMD) with DEET. Results: We found that An. coluzzii mosquitoes were repelled by lemongrass oil and PMD, while Ae. aegypti and Cx. Quinquefasciatus mosquitoes were repelled by lemongrass oil, PMD, eugenol, and DEET. In addition, we found that high concentrations of 1-octen-3-ol and benzaldehyde were repellent, and activated more olfactory receptor neurons on the An. coluzzii antenna than lower concentrations. Finally, we found that changes in olfactory responses to repellent mixtures reflected changes in repulsive behaviors. Conclusions: Our findings suggest that different species of mosquitoes have different behavioral responses to repellents. We further suggest that high-odor concentrations may recruit repellent-sensing neurons, or generally excite many olfactory neurons, yielding repellent behavioral responses. Finally, we show that DEET can decrease the neuronal and behavioral response of An. coluzzii mosquitoes towards PMD but not towards lemongrass oil. Overall, these studies can help inform mosquito repellent choice by species, guide decisions on effective repellent blends, and could ultimately identify the olfactory neurons and receptors in mosquitoes that mediate repellency.

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