Mating behavior of the rice stem borer moth, Chilo suppressalis Walker (Lepidoptera: Pyralidae). IV. Threshold-light-intensity for mating initiation under various temperatures

The effects of light-intensity and temperature on mating of the rice stem borer moth, Chilo suppressalis Walker, were investigated. The threshold-light-intensity for mating initiation varies with temperature. At as high a temperature as 30°C, mating was inhibited by a feeble light greater than 5 lux, but the threshold-light-intensity for mating initiation shifted higher rapidly with decreasing temperature, such as ca. 65 lux at 25°C, ca. 180 lux at 20°C, ca. 600 lux at 15°C. Also, mating was initiated by decrease of temperature within certain restricted light-intensity without light-off stimulation. This phenomenon seems to be evidence for the previous description that the threshold-light-intensity for mating initiation is varied by temperature. These results suggest that one of the resons of the seasonal variation of mating time is attributed to changing sensitivity of moths to light according to temperature to which they are exposed.