Single-stranded RNA viruses infecting the invasive Argentine ant, Linepithema humile

Abstract

Social insects host a diversity of viruses. We examined New Zealand populations of the globally widely distributed invasive Argentine ant (Linepithema humile) for RNA viruses. We used metatranscriptomic analysis, which identified six potential novel viruses in the Dicistroviridae family. Of these, three contigs were confirmed by Sanger sequencing as Linepithema humile virus-1 (LHUV-1), a novel strain of Kashmir bee virus (KBV) and Black queen cell virus (BQCV), while the others were chimeric or misassembled sequences. We extended the known sequence of LHUV-1 to confirm its placement in the Dicistroviridae and categorised its relationship to closest relatives, which were all viruses infecting Hymenoptera. We examined further for known viruses by mapping our metatranscriptomic sequences to all viral genomes, and confirmed KBV, BQCV, LHUV-1 and Deformed wing virus (DWV) presence using qRT-PCR. Viral replication was confirmed for DWV, KBV and LHUV-1. Viral titers in ants were higher in the presence of honey bee hives. Argentine ants appear to host a range of' honey bee' pathogens in addition to a virus currently described only from this invasive ant. The role of these viruses in the population dynamics of the ant remain to be determined, but offer potential targets for biocontrol approaches.Social insects carry a range of viruses that can have a major effect on host population dynamics. Perhaps the best known viral community is from honey bees, which has been the focus of considerable study due to their economic importance. A range of different factors are likely to contribute to colony collapse and bee declines in general, with viruses frequently considered key players 1, 2 . A recent review noted honey bees host 24 viruses, primarily in the Dicistroviridae and Iflaviridae families 3 . Of these, the Deformed wing virus (DWV) has been suggested as a likely candidate for the majority of global honey bee colony losses during the past 50 years 4 . Such viruses, however, are not restricted to honey bees. There is increasing evidence that these 'honey bee' viruses are common in a wide range of insect hosts [5][6][7] . Other social insects have been found to carry their own unique suites of viral pathogens. For example, over the last decade four viruses have been described from the red imported fire ant (Solenopsis invicta) 8 . These were the first viruses fully described from ants. Three of these viruses are positive-sense, single-stranded RNA (ssRNA) viruses, with one (Solenopsis invicta virus-1, SINV-1) assigned taxonomically to the Dicistroviridae family, one (Solenopsis invicta virus-3, SINV-3) in a proposed new family, Solinviviridae 9 and the third currently unclassified (Solenopsis invicta virus-2, SINV-2) 8, 9 ; The fourth virus is a DNA virus, and has been placed in the family Parvoviridae 10 . One of the three ssRNA viruses, SINV-3, shows promise as a biocontrol agent as it can cause significant mortality in laboratory fire ant colonies 11 . Metatranscriptomic and pyrosequencing techniques have proven particula...

Long‐term record of Argentine ant invasions reveals enduring ecological impacts

“…This latter finding agrees with our earlier resurvey (Holway 1995) as well as with studies conducted in Bermuda where the Argentine ant has persisted at particular sites over an approximately 30-yr period (Haskins and Haskins 1965, 1988, Crowell 1968, Lieberburg et al 1975. Such differences could include abiotic conditions, pathogens, pesticides, or other factors (Cooling et al 2011, Gruber et al 2017. Such differences could include abiotic conditions, pathogens, pesticides, or other factors (Cooling et al 2011, Gruber et al 2017.…”

Social environment affects the transcriptomic response to bacteria in ant queens

“…Insects, including L. humile , are known to harbor RNA viruses (Gruber et al, ; Shi et al, ) which may have an effect on host gene expression (Doublet et al, ; Gerth & Hurst, ). We studied whether viruses are present and potentially have an effect on the gene expression patterns by assembling all the reads that could not be mapped to the L. humile genome by using default settings in Trinity v2.5.1, and by doing database searches with the obtained contigs against National Center for Biotechnology Information (NCBI Resource Coordinators, ) RefSeq virus databases “viral.1.protein.faa” and “viral.2.protein.faa” (accessed 7 January 2018) using BLASTX 2.6.0+ with an e‐value threshold of 10 −4 .…”

“…Insects, including L. humile, are known to harbor RNA viruses (Gruber et al, 2017;Shi et al, 2016) which may have an effect on host gene expression (Doublet et al, 2017;Gerth & Hurst, 2017 faa" (accessed 7 January 2018) using BLASTX 2.6.0+ with an evalue threshold of 10 −4 . Contigs that matched insect viruses and that had a query coverage of at least 400 amino acids were used in the following steps.…”

Foodborne Transmission of Deformed Wing Virus to Ants (Myrmica rubra)

“…However, there are only few studies on virus transmission between honeybees and ants. DWV and Kashmir Bee Virus (KBV) presence plus replication was detected in invasive argentine ants (Linepithema humile) as well as presence of Black queen cell virus (BQCV) in Linepithema humile and Anoplolepis gracilipes [37][38][39]. Further, DWV and other honeybee viruses (BQCV, Israeli acute paralysis virus and Sacbrood virus) were detected in Camponotus sp.…”