[Properties of the nuclear polyhedrosis virus].

Four passages of Barathra brassicae L nuclear polyhedrosis virus (NPV) in Heliothis armigera Hbn caterpillars were carried out. B. brassicae NPV was found to be highly infective for caterpillars of both species. When H. armigera caterpillars were infected with B. brassicae NPV, reproduction of the latter occurred alongside with the induction of H. armigera latent virus. In subsequent passages the latent virus replaced the foreign NPV. It was noted in mixed infection that in the 2nd passage the activity of NPV decreased apparently due to interference of the viruses.