|Harrison, Robert - Bob|
|KEENA, MELODY - Forest Service (FS)|
Submitted to: Journal of Invertebrate Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/29/2016
Publication Date: 6/1/2016
Citation: Harrison, R.L., Rowley, D.L., Keena, M.A. 2016. Geographic isolates of Lymantria dispar multiple nucleopolyhedrovirus: Genome sequence analysis and pathogenicity against European and Asian gypsy moth strains. Journal of Invertebrate Pathology. 137:10-22.
Interpretive Summary: The gypsy moth is a serious pest of trees and forests in the United States since its introduction from Europe in the late 1800s. Asian strains of gypsy moth spread faster and are more damaging to trees than the European strains of gypsy moth already established in North America, posing a potential invasive threat to American forests. An environmentally safe insecticide for suppressing gypsy moth outbreaks has been developed from a gypsy moth virus. In this study, isolates of the gypsy moth virus from the United States, Europe, Russia, and Asia were examined to see how they differ genetically from each other and from the specific virus isolate used to make the gypsy moth insecticide. It was found that gypsy moth viruses isolated from Asia formed a group that was separate from gypsy moth viruses isolated from other parts of the world. Also, in laboratory bioassays against Asian gypsy moth larvae, the virus isolate composing the gypsy moth insecticide was less effective than other virus isolates. The information in this study contributes to progress towards improving gypsy moth virus-based insecticides, and will be of interest to those in academia, government, and industry who work with this group of insect viruses or with gypsy moth and its management to protect forest and shade trees.
Technical Abstract: Geographic isolates of Lymantria dispar multiple nucleopolyhedrovirus: Genome sequence analysis and pathogenicity against European and Asian gypsy moth strains. To evaluate the genetic diversity of Lymantria dispar nucleopolyhedrovirus (LdMNPV) at the genomic level, the genomes of three isolates of LdMNPV from Massachusetts, USA (LdMNPV-Ab-a624), Spain (LdMNPV-3054), and Japan (LdMNPV-3041) were sequenced and compared with four other previously determined LdMNPV genome sequences. The LdMNPV sequences were co-linear and contained the same homologous repeats (hrs) and clusters of baculovirus repeat orf (bro) gene family members in same relative positions in their genomes. Of 146 non-bro ORFs present in the genome of the representative isolate LdMNPV 5-6, 135 ORFs were found in every other LdMNPV genome, including the 37 core genes of family Baculoviridae, 26 genes common to subsets of the four baculovirus genera, and 33 additional ORFs conserved in the Autographa californica multiple nucleopolyhedrovirus-C6 genome. Phylogenetic inference with an alignment of the baculovirus core gene nucleotide sequences grouped isolates 3041 and 2161 (Korea) separately from a cluster containing isolates from Europe, North America, and Russia. Bioassays were carried out with a selection of isolates against larvae from six colonies of the European gypsy moth (Lymantria dispar dispar) and the Asian gypsy moth (L. dispar asiatica and L. dispar japonica). LdMNPV isolates 2161 (Korea), 3029 (Russia), and 3041 (Japan) exhibited a greater degree of pathogenicity against neonate larvae than LdMNPV from a sample of Gypchek. This study expands our knowledge of the genetic diversity of LdMNPV and provides information on the activity of LdMNPV isolates against the Asian gypsy moth, a potential invasive pest of North American trees and forests.