Abstract: Studies on the effect of temperature and illumination on the diapause induction of cotton bollworm (Helicoverpa armigera) population in Jiangsu show that temperature below 24℃ and illumination of < 12h were optimal for diapause induction. The critical length of illumination at 20,22,24 and 26℃ were 13h and 43min, 13h and 8min, 12h and 4min, and 12h and 7min, respectively. The fifth and sixth instar larvae were the sensitive stages of diapause indution. Their critical length of illumination was about 13h, which occurs in mid-September in Nanjing region, and the temperature in early September was found to be greatly related with the diapause rate.

Key words: Helicoverpa armigera, Diapause induction, Sensitive stage, community production, saturation threshold, climate warming, biomass allocation, alpine meadow, nitrogen addition