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To study the variability in induction and duration of diapause of different populations of Helicoverpa armigera, test insects of five populations of different locations were reared tor two generations and diapausing parameters and development period worked out. The average diapause duration for Ludhiana (76.3 days), Muktsar (102.3 days) and Ferozepur (105.5 days) being statistically at par were grouped as one type. The proportion of pupae those went into diapause was 72.3, 80.2 and 60.6 per cent for Ludhiana, Ferozepur and Muktsar, respectively. Whereas, the other two populations of Mansa and Hoshiarpur did not go into diapause under similar set of conditions, thus designated as a different group. The total development of Ludhiana population (98.4 days) was significantly faster than Ferozepur (132.4 days) and Muktsar (127./days) populations. The weight of diapausing pupae of Ferozepur (203.2 mg), Muktsar (210.0 mg) and Ludhiana (221.8 mg) populations were statistically at par. The reduction to the extent of 2.1 to 10.1 per cent in weight of diapausing pupa over non-diapausing one was obtained. The heterogeneity related to diapause observed in different populations suggests location specific studies in H. armigera.
Generations, Helicoverpa armigera, Population, Variability
