Cross infection studies with Heliothis zea using nuclear-polyhedrosis viruses from Trichoplusia ni

Abstract

Histopathological studies of the larvae of Trichoplusia ni and Heliothis zea infected with two morphologically distinct nuclear-polyhedrosis viruses from T. ni were conducted. Large polyhedra containing bundles or packets of rods embedded within the polyhedron (multiple embedded virus = MEV) were found in nuclei of cells of the fat body, hypodermis, tracheal matrix, connective tissue, and midgut epithelium and in some of the hemocytes of T. ni. Smaller polyhedra containing single rods embedded within the polyhedron (single embedded virus = SEV) were found in the same tissues but not in the midgut epithelium. Trichoplusia ni MEV was transmitted to Heliothis zea. Large polyhedra were formed in the nuclei of Heliothis cells of the hypodermis and tracheal matrix, frequently of the midgut epithelium, and rarely those of the fat body. The latter observation is a significant digression from the massive involvement of the fat body in H. zea infected with its specific nuclear-polyhedrosis virus (a SEV type). No cross transmission was obtained to H. zea when treated with the T. ni SEV type. Similarly, no cross transmission was obtained in T. ni when treated with H. zea-specific nuclear-polyhedrosis virus.