A histopathological study on the nuclear polyhedrosis of larva of Spodoptera litura

Abstract

Spodoptera larvae infected with nuclear polyhedrosis virus were obtained by feeding them on white-clover leaves dipped in polyhedral suspension. In the larvae, polyhedra first appeared in unmatured form, very rarely, in cells of three tissues, fat body, epidermis and tracheal matrix three days after the inoculation. Four days after, the polyhedra were recognized approximately 1/10 cells of the three tissues. The infected larvae were pink or beige, owing to coloration of the epidermis, especially in the outer surface. Five days after the inoculation, most cells of the three tissues showed the polyhedra. And the inclusion bodies appeared in some cells of testicular sheath and brains. The fat body began to break down, and the epidermis was speparated from the cuticle. The polyhedra were not recognized in nuclei of cells of muscle, epithelium of fore-, mid- and hind-guts, silk gland, Malpighian tubule. Six days after the inoculation, most of the larvae were killed by the polyhedrosis.