Virulence of nucleopolyhedroviruses from Orgyia pseudotsugata and Orgyia leucostigma (Lep., Lymantriidae) for early instars of the white‐spotted tussock moth, Orgyia thyellina

Abstract

The white‐spotted tussock moth, Orgyia thyellina, was found in Auckland, New Zealand, in 1995. An eradication campaign against this potential pest is currently underway, but in the event that it is unsuccessful, agents for population suppression will be required. As no pathogens were available from O. thyellina, two nucleopolyhedroviruses (NPVs) from Orgyia pseudotsugara (OpMNPV ‘VirtussTM’) and Orgyia leucostigma (OrleSNPV) were imported from Canada and tested for virulence against O. thyellina. At 105 polyhedral inclusion bodies per cm2 and above, 100% mortality was achieved with first to second instar larvae by 15 days. Molecular comparison of sequences from the pol gene region of each virus demonstrated that they were from different genotypic groups of NPVs.