Abstract: The paper studies the date of diapause termination and relationship between postdiapause development and temperatures in overwintering pupae of cotton bollworm, Helicoverpa armigera (Hubner), under both natural and controlled conditions in Nanjing. The results show that, in the area, overwintering pupae end diapause in about mid-December and subsequently remain in quiscence from late December to early March when spring temperatures are below the threshold for development. Postdiapause development resumes in mid-March and eyespots move gradually from late March to early April when temperatures reach about 10℃- 412℃. It was also found that, during postdiapause development, pupae show great differences in development rate, temperature threshold and protein concentration in haemolymph in the stage previous to eyespots movement, compared with the stage following eyespots movement and nondiapausing pupae.

Key words: Helicoverpa armigera, overwintering pupae, diapause termination, post- diapause development