Genotypic variation among Douglas-fir tussock moth nucleopolyhedrovirus (OpNPV) isolates in the western United States

► We assessed genotypic diversity in nucleopolyhedroviruses infecting Orgyia pseudotsugata in western USA. ► Single NPV were much more common and more polymorphic than multiple NPV. ► About half of the total genetic OpSNPV variability was attributed to large-scale geographic differences. ► The majority of OpMNPV samples shared the same genotype.