Diverse single-stranded DNA viruses associated with honey bees (Apis mellifera)

Honey bees (Apis mellifera) research has increased in light of their progressive global decline over the last decade and the important role they play in pollination. One expanding area of honey bee research is analysis of their microbial community including viruses. Several RNA viruses have been characterized but little is known about DNA viruses associated with bees. Here, using a metagenomics based approach, we reveal the presence of a broad range of novel single-stranded DNA viruses from the hemolymph and brain of nurse and forager (worker divisions of labour) bees belonging to two honey bees subspecies, Italian (Apis mellifera linguistica) and New World Carniolan (Apis mellifera carnica). Genomes of 100 diverse viruses were identified, designated into three groupings; genomoviruses (family Genomoviridae) (n = 4), unclassified replication associated protein encoding single-stranded DNA viruses (n = 28), and microviruses (family Microviridae; subfamily Gokushovirinae) (n = 70). Amongst the viruses identified, it appears that nurses harbour a higher diversity of these viruses comparative to the foragers. Between subspecies, the most striking outcome was the extremely high number of diverse microviruses identified in the Italian bees comparative to the New World Carniolan, likely indicating an association to the diversity of the bacterial community associated with these subspecies.