Honey bee viruses in the yellow-legged hornet Vespa velutina (Lepelieter 1836): Prevalence, loads, and detection of replicative DWV and LSV forms

Apiaries in Galicia, northwestern Spain, are currently facing the invasive alien species Vespa velutina, which is well established in the region. The pressure on honey bee colonies is high, resulting in both economic and ecological losses. Honey bee colonies also face the challenge of viruses, which are becoming increasingly diverse. In recent years, honey bee viruses have been spreading across taxonomic groups beyond Apoidea, infecting the Vespoidea superfamily. This cross-species spillover has raised concerns in the scientific community due to the potential risk of viruses spreading in ecosystems. Currently, there is a lack of knowledge on this topic, and further research is needed to address this issue. This study employed qPCR and sequencing to investigate the prevalence, loads, and presence of replicative forms of important honey bee viruses in V. velutina individuals collected from 11 apiaries in Galicia. All V. velutina individuals tested positive for DWV, BQCV, AKI complex (ABPV, KBV, and IAPV), or LSV but not for CBPV. DWV showed the highest prevalence (97.0 %) and loads, with both DWV-A (67.4 %) and DWV-B (32.6 %) being detected. The AKI complex (46.3 %) and LSV (43.3 %) were also common, whereas BQCV (11.9 %) was rarer. LSV is detected for the first time in V. velutina. LSV-2 was the dominant strain (82.1 %), and two less frequent (17.9 %) unknown strains were also detected. All 44 screened V. velutina samples carried the replicative form of DWV, and six of these also carried the replicative form of LSV, raising for the first time the possibility of co-infection in the hornet. The detection of honey bee viruses in V. velutina, and the ability of these viruses to spread to other species, may indicate a potential risk of spillover in the apiaries.