Selection of light or darkness, locomotor, and stridulatory activities in the cricket, Gryllus bimaculatus Degeer (Orthoptera: Gryllidae)

Male crickets, Gryllus bimaculatus Degeer, turned lights on or off in a chamber by a seesaw device: (1) during a 12 h, and (2) during a 24 h day. The crickets in (1) and the last-instar nymph in (2) turned the lights on and off at irregular intervals and duration. The selection rate for darkness was greater than that for light by an average exceeding 80%. The locomotor activity of the nymph in (1) was arrhythmic. In (1) the adults stridulated and were active in continuous darkness during the 12 h, while, in contrast in (2) they turned on the light and stridulated without switching the light off. The locomotor and stridulatory activities of the adult crickets in (2) were free-running. These activities resulted in a free-running rhythm of selection for light or darkness in (2). Under the conditions of the present experiments, the circadian pacemaker functioned in the same way in light and dark cycles as in constant light conditions.