Abstract
When insects communicate by sound, or use acoustic cues to escape predators or detect prey or hosts they have to localize the sound in most cases, to perform adaptive behavioral responses. In the case of particle velocity receivers such as the antennae of mosquitoes, directionality is no problem because such receivers are inherently directional. Insects equipped with bilateral pairs of tympanate ears could principally make use of binaural cues for sound localization, like all other animals with two ears. However, their small size is a major problem to create sufficiently large binaural cues, with respect to both interaural time differences (ITDs, because interaural distances are so small), but also with respect to interaural intensity differences (IIDs), since the ratio of body size to the wavelength of sound is rather unfavorable for diffractive effects. In my review, I will only shortly cover these biophysical aspects of directional hearing. Instead, I will focus on aspects of directional hearing which received relatively little attention previously, the evolution of a pressure difference receiver, 3D-hearing, directional hearing outdoors, and directional hearing for auditory scene analysis.
Highlights
In insect taxa which use acoustic signals for intraspecific communication, the recognition of the acoustic signals is crucial for their fitness, since it enables species identification and prevents hybridization (Gerhardt and Huber 2002; Greenfield 2002; Bradbury and Vehrencamp 2011)
Ears evolved in insects without acoustic signals, indicating that other functions of hearing may include the detection of cues from predators, or the detection of hosts in the case of parasitoids
In the case of particle velocity receivers such as the antennae of mosquitoes, or filiform hairs on the cerci directionality is no problem because such receivers are inherently directional
Summary
In insect taxa which use acoustic signals for intraspecific communication, the recognition of the acoustic signals is crucial for their fitness, since it enables species identification and prevents hybridization (Gerhardt and Huber 2002; Greenfield 2002; Bradbury and Vehrencamp 2011). Insects equipped with bilateral pairs of tympanate ears could principally make use of binaural cues for sound localization, like all other animals with two ears Their small size and interaural distance result in only minute interaural time differences (ITDs). Evolutionary modifications of anatomical structures (see below) resulting in the proper amplitude and phase shifts between internal and external pressure components could create highly directional ears despite unfavorable ratios of body size to the wavelength of sound. The interaural distance of 520 μm would create no more than 1.45 μs of ITD, and significant diffractive effects cannot play a role given the unfavorable ratio of body size to wavelength of sound (Robert et al 1996) Despite these limitations, the flies show very accurate acoustic localization behavior in flight (see below) and while walking (Mason et al 2001; Müller and Robert 2001). Future studies will show whether this reflects species differences or the influence of a more or less complex structured environment
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
