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Title: Genetic and biological variation among nucleopolyhedrovirus isolates from spodoptera frugiperda (lepidotpera: noctuidae)

item Rowley, Daniel
item Farrar, Robert
item Blackburn, Michael - Mike
item Harrison, Robert - Bob

Submitted to: Virus Genes
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/18/2010
Publication Date: 6/1/2010
Citation: Rowley, D.L., Farrar, R.R., Blackburn, M.B., Harrison, R.L. 2010. Genetic and biological variation among nucleopolyhedrovirus isolates from spodoptera frugiperda (lepidotpera: noctuidae). Virus Genes. 40:458-468.

Interpretive Summary: A moth called the fall armyworm is an important pest of corn. The use of chemical insecticides to kill this pest can have negative ecological, environmental, and health consequences. Baculoviruses are a group of insect viruses that can be used to kill insect pests without the problems of chemical insecticides. In this study, a large number of baculoviruses that potentially can kill the fall armyworm were examined. A method for quickly identifying and gathering information on baculoviruses was used to document genetic differences among the viruses. Doses of the viruses required to kill fall armyworm and the length of time that fall armyworm insects survived after being infected with the different viruses were also determined. The information in this study contributes to the progress towards developing baculoviruses that can be used as biopesticides against fall armyworm. Baculoviruses have a wide range of applications in addition to their use as biopesticides, and this study will be of interest to scientists in academia, government, and industry who work with this group of viruses.

Technical Abstract: A PCR-based method was used to identify and distinguish among 40 uncharacterized nucleopolyhedrovirus (NPV) isolates from the moth Spodoptera frugiperda that were part of an insect virus collection. Phylogenetic analysis was carried out with sequences amplified from two strongly conserved loci (polh and lef-8) and two less conserved SfMNPV-specific loci (hr4 and hr5) from the 40 isolates in the collection and from eight previously studied S. frugiperda NPV (SfMNPV) isolates. Phylogenetic inference from the sequence data could distinguish between several of the individual isolates and between different groups of isolates from Georgia (USA) and Colombia, South America. Sequencing and phylogenetic analysis detected a relatively high degree of larva-to-larva sequence divergence occurring among isolates of SfMNPV collected from the same field in Missouri, USA. Restriction endonuclease analysis of viral DNA from larvae infected with five isolates from Georgia, Missouri, Louisiana, Florida (USA), and Colombia allowed for further comparison with other previously reported isolates of SfMNPV. Bioassays with these five geographically distinct isolates detected minor differences in virulence. This study highlights the use of PCR to rapidly distinguish and characterize large numbers of historical baculovirus isolates from the same host using minimal quantities of material.