Presentation Type

Presentation

Faculty Mentor’s Full Name

Douglas J. Emlen

Faculty Mentor’s Department

Division of Biological Sciences

Abstract

Insects produce sound in wildly-diverse ways, from the vibrating wings of chirping crickets to the pulsating tympanum of whining of cicadas. Beetles (order: Coleoptera) use sound in aggressive displays, alarm calls, and courtship sequences. Although all beetles appear to generate sounds using stridulation, where a plectrum, or pick, is rubbed against a pars stridens, or file, species differ in the size and location of these structures, resulting in a diverse mechanistic array of sound production within this order. The Japanese rhinoceros beetle, Trypoxylus dichotomus, was recently observed stridulating during courtship sequences; however, the mechanism of sound production, including the body parts involved and their fine structure, were unknown. I used videos of singing males, topical applications of nail polish to putative file structures, and light and scanning electron microscopy (SEM), to localize and characterize the stridulatory apparatus. Here, I show that the pars stridens is located on the inside apical tip of each elytron, and it is scraped by a plectrum located on the dorsal surface of the abdomen. By either pumping the abdomen forward and back, or swiping it side to side, males are able to produce two distinct types of acoustic signals. Future studies will explore the properties of the male courtship song and the details of female preference.

Category

Life Sciences

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Read First - Submission Contents

Singing Beetles_Presentation Only.pdf (112230 kB)
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Singing Beetles? Figuring out how male rhinoceros beetles produce their courtship songs.

Insects produce sound in wildly-diverse ways, from the vibrating wings of chirping crickets to the pulsating tympanum of whining of cicadas. Beetles (order: Coleoptera) use sound in aggressive displays, alarm calls, and courtship sequences. Although all beetles appear to generate sounds using stridulation, where a plectrum, or pick, is rubbed against a pars stridens, or file, species differ in the size and location of these structures, resulting in a diverse mechanistic array of sound production within this order. The Japanese rhinoceros beetle, Trypoxylus dichotomus, was recently observed stridulating during courtship sequences; however, the mechanism of sound production, including the body parts involved and their fine structure, were unknown. I used videos of singing males, topical applications of nail polish to putative file structures, and light and scanning electron microscopy (SEM), to localize and characterize the stridulatory apparatus. Here, I show that the pars stridens is located on the inside apical tip of each elytron, and it is scraped by a plectrum located on the dorsal surface of the abdomen. By either pumping the abdomen forward and back, or swiping it side to side, males are able to produce two distinct types of acoustic signals. Future studies will explore the properties of the male courtship song and the details of female preference.