Nudivirus sequences identified from the southern and western 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: 2/2/2021
Publication Date: 2/9/2021
Citation: Liu, S., Sappington, T.W., Coates, B.S., Bonning, B.C. 2021. Nudivirus sequences identified from the southern and western corn rootworms (Coleoptera: Chrysomelidae). Viruses. 13(2). Article 269. https://doi.org/10.3390/v13020269.
DOI: https://doi.org/10.3390/v13020269

Interpretive Summary: Western corn rootworm (WCR), and to a lesser extent southern corn rootworm (SCR), are significant pests of maize in the United States, causing severe economic losses. Given the resistance of WCR to many current control methods, efforts are underway to devise novel virus-based management tactics for this pest. 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, two novel nudiviruses were identified, one each from WCR and SCR. The nudivirus genome sequence from SCR was nearly complete, while the one found in WCR was only partial. By comparing the DNA sequences of these two new nudiviruses with those described for other insects, including the only other known nudivirus from a beetle, we were able to clarify how such viruses from different host invertebrates are related to one another. 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: Analysis of genome sequence data revealed the presence of nudivirus-derived sequences from U.S. populations of both southern corn rootworm (SCR, Diabrotica undecimpunctata howardi Barber) and western corn rootworm (WCR, Diabrotica virgifera virgifera LeConte). A near complete nudivirus genome sequence was assembled from sequence data for an SCR population with relatively high viral titers. A total of 147,179 bp was assembled from five genome fragments that encode 109 putative ORFs including 20 nudivirus core genes. In contrast, genome sequence recovery was incomplete for a second nudivirus from WCR, although sequences derived from this virus were present in three geographically dispersed populations. Only 48,989 bp were assembled with 48 putative ORFs including 13 core genes, representing about 20% of a typical nudivirus genome. On phylogenetic analysis, both corn rootworm nudiviruses grouped with the third known nudivirus of beetles, Oryctes rhinoceros nudivirus in the genus Alphanudivirus. On the basis of phylogenetic and additional analyses, we propose further taxonomic separation of nudiviruses within Alphanudivirus and Betanudivirus into two subfamilies and five genera. Identification of nudivirus-derived sequences from two species of corn rootworm highlights the diversity of viruses associated with these agricultural insect pests.