Abstract: In order to understand the effects of night-interruption on diapause-averting by different geographic populations of the Asian corn borer, Ostrinia furnacalis (Guenée), the photoperiodic responses and effects of night-interruption experiments on diapause-averting in two populations of O. furnacalis from Nanchang (28°41′N， 115°53′E) and Harbin (44°56′N， 127°10′E) were investigated in the laboratory, in which the scotophases of L9∶D15 and L12∶D12 were interrupted by 1 h light pulse at 25 and 28℃, respectively. The results showed that the critical daylengths in Harbin population at 25 and 28℃ were 1 h 40 min and 2 h longer than those in Nanchang population, respectively. In all night-interruption experiments, the incidences of diapause in almost all positions of light pulse in Nanchang population were significantly lower than that in Harbin population. When the light pulse was used to interrupt L9∶D15 and L12∶D12, the incidence of diapause was lower at L9∶D15 than that at L12∶D12. Furthermore, the most highly photo-sensitive position occurred in the middle of scotophase at L9∶D15, whereas the most highly photosensitive position occurred in the early scotophase at L12∶D12. The effect of the light pulse on diapause-averting at 28℃ was greater than that at 25℃. These results further suggest that effect of night-interruption on diapause-averting may be different even in the same species depending on different geographic populations and the experimental conditions.

Key words: Ostrinia furnacalis, night-interruption experiment, light pulse, diapause induction, photoperiod, temperature, geographic population