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Ultrasound acoustic startle response in scarab beetles
T G Forrest1, H E Farris, R R Hoy
1Section of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA.
The Journal of Experimental Biology
|December 1, 1995
Summary
This study reveals that the scarab beetle Euetheola humilis possesses an auditory sense, enabling it to detect ultrasound. This hearing ability aids in predator evasion, particularly from bats.
Area of Science:
- Zoology
- Bioacoustics
- Insect Behavior
Background:
- Scarab beetles are primarily known for their non-auditory senses.
- Many nocturnal insects utilize auditory cues for predator detection.
- The auditory capabilities of scarab beetles remained largely unexplored.
Purpose of the Study:
- To investigate the presence and characteristics of an auditory sense in the night-flying scarab beetle, Euetheola humilis.
- To determine the functional significance of this auditory sense in the context of predator avoidance.
Main Methods:
- Field experiments involving ultrasound playback and beetle trapping.
- Laboratory behavioral assays to assess auditory sensitivity.
- Electromyographic recordings to analyze neural responses to auditory stimuli.
Main Results:
- Euetheola humilis demonstrated sensitivity to ultrasound frequencies (20-70 kHz) simulating bat echolocation.
- Beetles exhibited evasive maneuvers, including a head roll response, correlated with stimulus intensity.
- A short response latency (30-40 ms) was recorded, indicative of rapid predator detection.
Conclusions:
- Euetheola humilis possesses a functional auditory system for detecting airborne sounds.
- This auditory sense provides an effective mechanism for evading insectivorous bats.
- The findings highlight convergent evolution of ultrasound detection for predator avoidance in nocturnal insects.
