PATHOGENICITY OF THE IRELAND STRAIN OF NUCLEAR POLYHEDROSIS VIRUS TO SPRUCE BUDWORM, CHORISTONEURA FUMIFERANA, LARVAE

Abstract

The spruce budworm, Choristoneura fumiferana (Clem.), nuclear polyhedrosis virus (CfMNPV) has been studied extensively for its potential use as a bio-insecticide (Cunningham 1995). Recent advances in recombinant DNA technology have been impetuous in the genetic engineering of this virus to increase its virulence and (or) speed of action. This aspect of research has been concentrated on the modification of a plaque purified (Ireland strain) isolate obtained from the wild-type virus population (Arif et al. 1984). To assess any improvement in the effectiveness against the target pest, the virulence of the unaltered virus must first be determined. Bioassay results that have been previously reported by Kaupp and Ebling (1990) were conducted on the wild-type virus found in nature which consists of a mixture of viruses (Arif et al. 1994). Results of bioassays conducted to determine dose–response and time–response of fifth-instar spruce budworm larvae to the Ireland strain of CfMNPV are reported here.