THE EFFECT OF METAMORPHOSIS ON NUCLEAR-POLYHEDROSIS VIRUS INFECTION IN CERTAIN LEPIDOPTERA.

In Lepidoptera, the course of nuclear-polyhedrosis virus infection is interrupted at periods of rapid cell proliferation such as those that occur during the formation of the pupa and adult. Embryonic regenerative cells appear to be resistant to virus attack but they become susceptible after they have begun to differentiate. Thus, the new structures they form must be infected and killed before the insect will die. In this way, the incubation period of the disease is increased. When larvae were fed polyhedra 3 to 5 days before pupation, significant mortality occurred during the pupal stage.