Prevalence and distribution of two polycipiviruses in wild black garden ants (Lasius niger L.) in the Netherlands

Metagenomic studies have revealed diverse viruses in insects. Yet, our understanding of the ecology of insect viruses, especially in ants, remains limited, despite the insects' ecological importance. Viruses of the family Polycipiviridae are increasingly recognized as widespread yet poorly characterized components of ant viromes. In this study, we investigated the prevalence and genetic diversity of Lasius niger virus 1 (LniV-1) and Myrmica scabrinodis virus 1 (MsaV-1) in wild colonies of the black garden ant (Lasius niger L.) across the Netherlands. We surveyed 40 wild L. niger colonies, sampled at geographically distinct locations, using RT-PCR to assess viral prevalence and genetic diversity. Viral prevalence was estimated at both colony and individual levels. Amplicons were sequenced to explore potential correlations between geographic distribution and genetic diversity for both viruses. In addition, complete or almost complete viral genome sequences were obtained and assembled for one MsaV-1 genome from Groningen, The Netherlands, and one MsaV-1 and one LniV-1 from Vienna, Austria. In the Netherlands, LniV-1 was detected in 17.5% of colonies, whereas MsaV-1 was detected in 27.5%, including evidence of co-infection at the colony level. Neither the geographical distribution of infected colonies nor the inferred phylogenies for both viruses showed strong geographic structuring. The prevalence in workers within colonies was variable, ranging from 10 to 60%. These findings suggest that polycipiviruses are common in natural L. niger populations and may transmit via both horizontal and vertical routes. This study provides baseline data on ant-virus interactions in natural environments, advancing understanding of viral ecology in social insects and informing future research on virus transmission dynamics in natural ecosystems.