Abstract

                                Attempts were made to establish new cell lines from the embryos of Helicoverpa armigera (Hübner) to study its susceptibility to baculoviruses. Three primary cell cultures were initiated from the embryo of H. armigera. Among the three cultures, HaE9 alone produced sufficient cell growth to allow subculturing and led to establishment. Population doubling time (PDT) of the cell line HaE9 ranged from 3.63 days to 4.75 days for five consecutive generations. Susceptibility studies of different baculoviruses revealed that HaE9 was permissive for HearNPV alone. Studies on the influence of incubation temperature regimes (26 o , 27 o and 28 o C) on cell infection and polyhedral occlusion body (POB) yield of HearNPV in HaE9 cell line revealed that the temperature regime of 27 o C could yield a maximum of 5.63 and 5.75x10 7 POB/ ml in 20 th and 21 st passage respectively. Bioassays with cell cultured viruses in comparison with in vivo produced virus had similar effects against 2 nd instar H. armigera larvae with LC 50 values of 0.029 and 0.017 POB/mm 2 , respectively.

Key words : Helicoverpa armigera, Cell line, Population doubling time, Temperature