Sequences encoding a novel toursvirus identified from southern and northern corn rootworms (Coleoptera: Chrysomelidae)

Authors: LIU, SIJUN - Iowa State University; Sappington, Thomas; Coates, Brad; BONNING, BRYONY - University Of Florida

Submitted to: Viruses
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/7/2022
Publication Date: 2/15/2022
Publication URL: https://handle.nal.usda.gov/10113/7685437
Citation: Liu, S., Sappington, T.W., Coates, B.S., Bonning, B.C. 2022. Sequences encoding a novel toursvirus identified from southern and northern corn rootworms (Coleoptera: Chrysomelidae). Viruses. 14(2). Article 397. https://doi.org/10.3390/v14020397.
DOI: https://doi.org/10.3390/v14020397

Interpretive Summary: Northern corn rootworm (NCR) and southern corn rootworm (SCR) are significant pests of maize in the United States, causing severe economic losses. Given the resistance of corn rootworms to many current control methods, efforts are underway to devise novel virus-based management tactics for these pests. One way to discover viruses that may infect a pest insect species is to look for virus-derived sequences embedded within genome sequence data from the insect. Using this approach, a novel toursvirus was identified from both NCR and SCR. Toursviruses are generally considered to be in the family of Ascoviridae. By comparing the DNA sequence of the new toursvirus to those of ascoviruses and to those of the few toursviruses that have been described for other insects, we were able to clarify how such viruses from different host invertebrates are related to one another. Knowing these relationships will help predict the potential of the toursvirus to infect individual rootworms and to suppress populations. This information will be used by university, government, and industry scientists in their search for, and development of, possible biocontrol agents that can suppress populations of rootworms and other beetle pests of crops.

Technical Abstract: The corn rootworm complex is responsible for over $2B in annual corn losses and control costs, but management is increasingly difficult because of increasing development of resistance to management tactics. The use of pathogenic viruses could provide a new way of suppressing pest populations. To assess the potential for virus-based suppression of corn rootworms, we continue to examine the associated viromes, drawing on both genomic and transcriptomic sequence data. We report the discovery and annotation of a novel toursvirus based on sequences derived from both southern and northern corn rootworm. The data indicate that the toursvirus isolates from the two rootworm species derive from the same or similar viruses. The toursvirus is named Diabrotica toursvirus 3 (DiTV3), and is the first Ascoviridae virus isolated from Coleoptera. Based on phylogenetic analyses of sequences from a DNA polymerase and a capsid protein, we propose that the genus Toursvirus be separated from Ascoviridae, and a new family Toursviridae created within the order Pimascovirales. Pimascovirales would then contain four families: Ascoviridae, Iridoviridae, Marseilleviridaes and Toursviridae.