Directional vibration sensing in the termite Macrotermes natalensis

Area of Science:

• Animal Behavior
• Sensory Biology
• Bioacoustics

Background:

• Insects' ability to localize vibration sources is known, but the mechanism for directional perception on solid substrates remains unclear.
• The termite Macrotermes natalensis uses vibrational drumming for communication, especially during predator attacks, triggering colony defense responses.

Purpose of the Study:

• To investigate how Macrotermes natalensis soldiers perceive directional vibratory signals for colony defense.
• To determine the specific cues used by termites for localizing vibration sources on solid substrates.

Main Methods:

• Field observations of termite recruitment towards vibrational signals.
• Arena experiments using natural nest material to assess vibration localization.
• Controlled experiments with movable platforms to manipulate time-of-arrival differences in vibratory stimuli applied to termite legs.

Main Results:

• Macrotermes natalensis soldiers were effectively recruited towards the source of vibrational signals in field and arena settings.
• Soldiers demonstrated the ability to localize the vibration source on natural nest material.
• A time-of-arrival difference as small as 0.2 ms was sufficient for soldiers to detect the direction of the vibration source.
• Soldiers exhibited positive tropotaxis towards the earlier stimulated platform, indicating a preference for the direction of the initial vibration.

Conclusions:

• Macrotermes natalensis soldiers utilize time-of-arrival differences in vibrations as a primary cue for directional sensing on solid substrates.
• This study provides the first evidence of time-of-arrival delay perception and vibrotropotaxis in insects on solid substrates, crucial for effective colony defense.