A Newly Discovered Nuclear Polyhedrosis of the Small Blackish Cochlid, Scopelodes contracta WALKER

Symptomatological and histopathological features of a newly discovered nuclear polyhedrosis of the small blackish cochlid, Scopelodes contracta, were described. The virus was pathogenic to the fat body, hypodermis, trachea, and the muscle, but it was not pathogenic to the midgut, silkgland, and Malpighian tubes. The progression of the disease was similar to that of other nuclear polyhedrosis type. Electron micrographs revealed that each hypertrophied nucleus of infected cell contained a central chromatin mass having a micronet structure and a number of “naked” virus rods protruded from the strands of dense material of network into the spaces between the strands. Some of the mature virions were seen outside of the chromatin mass or in the minute polyhedra developing interior to the nuclear membrane. Simultaneously, development of fibril structure was seen both in the nucleus and in the cytoplasm, suggesting that the production of fibrillar masses was certainly related to the synthesis of polyhedral protein. The size of ovoid or irregular-shaped polyhedra varied from