Light curtails sleep in anesthetized hornets: extraretinal light perception

Area of Science:

• Insect physiology
• Photobiology
• Animal behavior

Background:

• Anesthesia in insects can induce a sleep-like state.
• Light perception in insects is not solely reliant on compound eyes.

Purpose of the Study:

• To investigate the effect of light on the sleep duration of anesthetized hornets (Vespa orientalis).
• To determine the influence of light intensity and spectral composition on hornet wake-up times.
• To explore the role of extraretinal light perception in this response.

Main Methods:

• Anesthesia of hornets (Vespa orientalis) using diethyl ether.
• Measurement of sleep duration in dark conditions and under varying light intensities and wavelengths.
• Comparison of wake-up responses to halogen and mercury lamps, with a focus on U.V. light.

Main Results:

• Polychromatic light significantly shortened sleep duration, with higher intensity leading to quicker wake-up.
• Mercury lamps, with higher U.V. output, induced shorter sleep times than halogen lamps.
• Near U.V. light (300-400 nm) was most effective in eliciting wake-up; longer wavelengths had minimal effect.
• Hibernating queens exhibited longer sleep times than workers and drones.

Conclusions:

• Light, particularly near U.V. wavelengths, acts as a potent stimulus for waking anesthetized hornets.
• The findings support the hypothesis of extraretinal light perception in Vespa orientalis.
• Differences in sleep duration between castes may relate to physiological states or light sensitivity.