THE PERSISTENCE OF A NUCLEAR POLYHEDROSIS VIRUS IN THE HABITAT OF THE HOST INSECT, TRICHOPLUSIA NI II.: POLYHEDRA IN SOIL

Abstract

AbstractThe viral activity of soil treated with polyhedra of the cabbage looper, Trichoplusia ni (Hübner), was determined at intervals by bioassay. Soil in plots treated in 1961 at a rate of 6.4 × 1010 polyhedra per square meter of surface contained about 25% of the original infective virus more than 5 years after treatment. A similar rate of decline in viral activity occurred in plots treated with polyhedra in 1963. Viral activity of soil retained under artificial conditions decreased more rapidly.Field and laboratory tests showed that foliage of cruciferous plants grown in soil treated with polyhedra was contaminated with the virus, probably largely by virus-laden soil being splashed onto foliage by rain.