Circadian rhythm of light sensitivity in the beetle Coccinella septempunctata (Coleoptera,Coccinellidae): Effects of illumination and temperature

Beetles Coccinella septempunctata L. are active only during daylight. It is demonstrated that sensitivity to light, the photopreferendum, and locomotor activity are regulated by endogenous circadian oscillators. The percentage of beetles that became active during the first 10 min after light-on was determined. Sensitivity to light (100, 1000 or 7000 lx) reached the maximum in the daytime (period of activity) and the minimum at night (resting period) irrespective of temperature (17 or 26°C). Illumination and temperature serve as modifying factors for the pattern and amplitude of the circadian rhythm of light sensitivity.