PRODUCTION OF AGROTIS-SEGETUM GRANULOSIS-VIRUS IN DIFFERENT LARVAL INSTARS OF A-SEGETUM (LEP, NOCTUIDAE)

Virus yields from Agrotis segetum larvae infected in the third, fourth and fifth instar with an A. segetum granulosis virus (AsGV) were dete rmined in terms of numbers of inclusion bodies. The number of inclusio n bodies produced per larva was found to be inversely related to the i nstar of inoculated larvae. A greater yield of virus was obtained from larvae that had moulted after ingestion of virus inoculum than from t hose which died without moulting. Female larvae produced more virus th an male larvae. The viruses obtained from third and fourth instar larv ae had the highest regression line slopes with significant differences with respect to original inoculum. In general, the viral products wer e more virulent than the original inoculum but the differences were si gnificant for viruses produced in larvae that died in the inoculation instar. The virus obtained from fifth instar larvae showed a significa ntly higher virulence when it was produced in male rather than female larvae.