The effects of endogenous and exogenous factors on mating behaviour were investigated to clarify the mechanisms of mating initiation, as one of the fundamental studies on the rice stem borer, Chilo suppressalis. The periodicity of mating behaviour is controlled basically by an endogenous circadian rhythm, and it is further affected by exogenous factors, such as temperature, day length, light intensity, light wave length and so on. Seasonal variations of mating behaviour can be observed under field conditions. The time of the onset of mating behaviour in August was delayed about 2 hours compared with that of June. Such variation of mating periodicity can be ascribed to the change in the hours of female calling and male pheromone response under different conditions among the seasons. Some of the important behavioural and physiological phenomena concerning mating initiation of Chilo suppressalis are discussed.
