THE EFFECT OF METAMORPHOSIS ON THE MULTIPLICATION OF AN INSECT VIRUS

Abstract

The prepupal stage of the European spruce sawfly is immune to infection by a polyhedral virus disease. The virus multiplies only in the nuclei of the digestive cells of the mid-gut epithelium and during metamorphosis these are replaced by embryonic cells not susceptible to infection although they develop into digestive cells eventually. The prepupal mid-gut, a temporary gut, is composed entirely of embryonic cells. New digestive cells appear later in the pupal and adult stages and these rapidly become infected with virus.