Abstract: The developmental duration of larvae and pupae and the dynamics of different geographical populations of cotton bollworm in Beijing region were investigated in the laboratory and field. The results indicated that there was no significant difference of larval development among geographical populations, but the diapause dynamics between south and north populations in the nature environment showed a great variation, and the dates for attaining 50% diapause rate of pupae in the populations from Hunan Province and Siehuan Province were 30 d and 22 d later than that of Beijing population. Based on the analysis on developmental dynamics of the populations, cold hardiness of cotton bollworm and climate environment, it was suggested that Beijing area would be the north boundary of ecological region for north population of cotton bollworm, and it was impossible for south population to finish yearly life history in north China.

Key words: Helicoverpa armigera, geographical population, fitness