Abstract: The characteristics of diapause termination for 13 populations of cotton bollworm, Helicoverpa armigera (Htibner), collected from various geographical regions in China, were investigated in the laboratory. The results showed that the developmental duration of diapausing pupae prolonged with the increase of latitude where the population was collected, for instance, that of Hengyang population (low latitude) and Hamipopulation (high latitude) were (15.6±4.9) days and (41.4±9.0) days at 30℃ respectively. The diapausing durations of the populatins from central and north China could besignificantly shortened by low temperature treatment, but it only played a slight role on the population from southern China. The developmental thresholds and effective accumulated temperatures of the vernalized diapause pupae of the populations from south,central, north and northwest China were 17.4℃ and 146.0 degree-day, 16.6℃ and 146.5 degree-day, 15.7℃ and 156.4 degree-day, and 15.7℃ and 167.7 degree-day, respectively.

Key words: cotton bollworm, diapause terminatiorl, geographical population