Flight muscle resting potential and species-specific differences in chill-coma.

Area of Science:

• Insect physiology
• Environmental stress response
• Neurobiology

Background:

• Insect flight muscles exhibit temperature-dependent electrical activity.
• Chill-coma is a critical temperature-induced state affecting insect survival.
• Understanding the physiological basis of chill-coma is vital for predicting insect responses to climate change.

Purpose of the Study:

• To investigate the relationship between resting potential decline and the onset of chill-coma in insects.
• To compare the temperature thresholds for chill-coma induction in different insect species.
• To analyze changes in muscle action potentials (MAPs) preceding chill-coma.

Main Methods:

• Electrophysiological recordings of flight muscle resting potentials and MAPs.
• Controlled temperature experiments to induce chill-coma.
• Comparative analysis across Apis mellifera (honeybee) and Drosophila melanogaster (fruit fly) species.

Main Results:

• Resting potentials in both species decrease with falling temperatures, triggering spontaneous MAPs that signal chill-coma onset.
• Drosophila melanogaster enters chill-coma at a significantly lower temperature (7.0°C) than Apis mellifera (workers: 10.6°C, queens: 10.2°C, drones: 12.8°C).
• MAP amplitude decreased while duration increased with falling temperatures prior to chill-coma in both species.

Conclusions:

• Insect chill-coma onset is directly related to the temperature-dependent decline in muscle resting potential.
• Species-specific differences in chill-coma temperature thresholds correlate with their ability to maintain resting potential at low temperatures.
• These findings provide insights into insect thermoregulation and vulnerability to cold stress.