Effects of Propagating Autographa californica Nuclear Polyhedrosis Virus and Its Trichoplusia ni Variant in Different Hosts 12

When polyhedra of Autographa californica passaged several times in Spodoptera exigua were passaged in Trichoplusia ni , the size of the polyhedra increased considerably. In addition, these polyhedra contained more virions per cross section of polyhedral inclusion body (PIB), contained a greater mean and mode of nucleocapsids per virion, and were more virulent to neonate T. ni . The polyhedra of T. ni after several passages in T. ni were not altered in size when passaged in S. exigua . However, these polyhedra had more virions per cross section of PIB, had a greater mean and mode of nucleocapsids per virion, and were more virulent to neonate T. ni than were PIBs of T. ni produced in T. ni larvae.