Auditory thresholds in the American cockroach (Orthoptera: Blattidae): estimates using single-unit and...

Area of Science:

• Neuroethology
• Insect Physiology
• Acoustic Sensory Biology

Background:

• Commercial pest control strategies increasingly suggest ultrasound for insect population management.
• This raises critical questions about the auditory capabilities and sensory receptors of various insect species.

Purpose of the Study:

• To investigate the auditory sensitivity of the American cockroach (Periplaneta americana L.) to high-frequency sounds.
• To determine the upper limit of hearing in cockroaches and explore the neural mechanisms involved.

Main Methods:

• Recording neural unit discharges and compound-action potentials from the ventral nerve cord of Periplaneta americana L.
• Utilizing constant rise time tone pulses across a frequency range of 100 to 40,000 Hz.

Main Results:

• Cockroaches demonstrated insensitivity to sounds exceeding approximately 3,000 Hz.
• Analysis of response latency versus stimulus intensity suggested the cercal system operates via energy envelope detection.
• Decreased latency correlated with increased membrane depolarization rates in cercal dendrites.

Conclusions:

• The American cockroach possesses limited auditory sensitivity, with an upper hearing limit around 3,000 Hz.
• The cercal system's detection mechanism appears to be based on energy envelope detection.
• Findings challenge the broad applicability of ultrasound as a sole method for cockroach control.