A NUCLEAR AND A CYTOPLASMIC POLYHEDRAL VIRUS DISEASE OF THE SPRUCE BUDWORM

Abstract

The spruce budworm, Choristoneura fumiferana (Clem.), is susceptible to two polyhedral virus diseases. The first, previously described, is characterized by the formation of polyhedra within the nuclei of tracheal matrix, fat, hypodermal, and blood cells. The polyhedra contain mostly rod-shaped particles 260 × 28 millimicrons. The second is a new type and is characterized by the formation of polyhedra in the cytoplasm of mid-gut cells. The polyhedra contain only spherical particles from 28 to 80 mμ in diameter. Both diseases occurred in the same insect but it was possible to separate the cytoplasmic disease from the nuclear disease by extracting groups of the cytoplasmic polyhedra from the mid-gut with a micromanipulator before the nuclear disease developed.