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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Invasive Insect Biocontrol & Behavior Laboratory » Research » Publications at this Location » Publication #376552
Research Project: Urban Small Farms and Gardens Pest Management

Location: Invasive Insect Biocontrol & Behavior Laboratory

Title: Insecticidal properties of isolates of Spodoptera frugiperda multiple nucleopolyhedrovirus against corn-strain and rice-strain fall armyworm, and complete genome sequences of three isolates from the USA and Colombia

Author
item POPHAM, HOLLY J. - Agbitech
item Rowley, Daniel
item Harrison, Robert - Bob

Submitted to: Journal of Invertebrate Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/17/2021
Publication Date: 7/1/2021
Citation: Popham, H.R., Rowley, D.L., Harrison, R.L. 2021. Insecticidal properties of isolates of Spodoptera frugiperda multiple nucleopolyhedrovirus against corn-strain and rice-strain fall armyworm, and complete genome sequences of three isolates from the USA and Colombia. Journal of Invertebrate Pathology. https://doi.org/10.1016/j.jip.2021.107561.
DOI: https://doi.org/10.1016/j.jip.2021.107561

Interpretive Summary: The fall armyworm is an important insect pest of corn, sorghum, rice, and wheat. This insect is usually found in North and South America, but in recent years it has spread to Africa and Asia. The use of chemical insecticides to kill this pest can have negative ecological, environmental, and health consequences. Naturally occurring insect viruses have been used in the past to kill insect pests like the fall armyworm without the problems associated with chemical insecticides, and an insect virus-based product is currently available for use against fall armyworm in the USA and Brazil. In this study, different isolates of a fall armyworm virus were evaluated in bioassays against two different strains of fall armyworm, and isolates with superior insecticidal activity were identified. Features of the genome sequences of three of these isolates were characterized and described. This information will be of interest to those in academia, government, and industry who are trying to develop environmentally-friendly forms of insect control.

Technical Abstract: The fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) is a destructive crop pest native to North and South America that recently has spread to Africa and Asia. Isolates of Spodoptera frugiperda multiple nucleopolyhedrovirus (SfMNPV) have potential to be developed as low-risk biopesticides for management of fall armyworm, and a commercially available formulation has been developed for control of fall armyworm in North America. In this study, the pathogenicity (LC50) and virulence (LT50) of several SfMNPV isolates towards larvae of both corn-strain and rice-strain fall armyworm were assessed. Bioassays with corn-strain larvae revealed that the isolates could be organized into fast-killing (LT50 < 67 hours post-infection) and slow-killing (LT50 > 68 hours post-infection) groups. Rice-strain larvae exhibited narrower ranges of susceptibility to baculovirus infection and survival times in bioassays with different isolates. Two SfMNPV isolates with rapid speeds of kill (SfMNPV-459 from Colombia and SfMNPV-1197 from Georgia, USA) along with an isolate that killed corn-strain at relatively low concentrations (SfMNPV-281 from Georgia) were selected for the complete determination of their genome sequences. The SfMNPV-1197 genome sequence shared high sequence identity with genomes of a Nicaraguan isolate (SfMNPV-B and -G), while SfMNPV-281 grouped with SfMNPV-3AP2 from Missouri, USA by phylogeny. SfMNPV-459 contained homologs of two ORFs that were unique to another Colombian isolate, SfMNPV-ColA. However, isolates 459 and ColA were not placed in the same clade in phylogenetic trees. This study identifies isolates with superior properties for control of fall armyworm and adds to our knowledge of the genetics of SfMNPV.