Damayo, J. E. | bioRxiv Science

bioRxiv2026

Landscape viromics of introduced honeybees and bumblebees reveal distinct environmental and host-specific effects

Understanding how viral communities vary across co-occurring hosts and environments is essential for assessing species-specific viral risks under changing land use and climate. This is particularly relevant for managing introduced bees, which face persistent viral threats themselves, as well as transmitting plant viruses. Here, we compare RNA viromes of the long-established honeybee (Apis mellifera, introduced to Tasmania in 1831) and the more recent invader, the bumblebee (Bombus terrestris, invasive since 1992), across 14 Tasmanian sites - an island still free of the viral vector, Varroa destructor. Using a metatranscriptomic approach on total RNA from whole bees, we identified insect- and plant-associated viruses and inferred phylogenetic patterns of insect viral sharing, divergence, and potential cross-species transmission. We also assessed spatial and environmental drivers of viral composition, diversity, and richness. Geographic longitude, precipitation, temperature, and pasture percentage influenced the total, insect-, and plant-associated viromes of B. terrestris. In contrast, for A. mellifera, only precipitation and temperature were associated with insect and plant viral alpha diversity and community composition. Phylogenetic analyses revealed that Black Queen Cell virus in A. mellifera from Tasmania has diverged from mainland Australian sequences, and two distinct sub-strains of Lake Sinai virus 1 were shared by both bee species. Lake Sinai virus 3 showed evidence of interspecies transmission between A. mellifera and B. terrestris. Notably, this study provides the first detection of Moku virus in Australian bees and globally in bumblebees, suggesting potential interspecies transmission among social Hymenoptera. Overall, our findings demonstrate local viral diversification and reveal that B. terrestris viromes are more strongly shaped by environmental factors than those of A. mellifera, underscoring the importance of monitoring invasive pollinators as reservoirs and vectors of viral emergence.

evolutionary biology↗

bioRxiv2023

Virus replication in the honey bee parasite, Varroa destructor

Arthropod vectors such as mites and ticks introduce an alternative viral transmission route between their hosts. The ectoparasitic mite Varroa destructor is the leading threat to the health of Western honey bees (Apis mellifera) primarily through its action as a vector of viruses. However, it is unclear whether viruses transmitted by V. destructor actively infect and replicate in mites, which could facilitate increased transmission and select for more virulent strains. To better understand the role of V. destructor as a vector, we took advantage of differences between bee and mite antiviral RNA interference pathways to identify the host specificity of replicating viruses. We used small RNA sequencing of individual V. destructor mites to examine viral small interfering RNA (vsiRNA) profiles of Deformed wing virus genotypes (DWV-A and DWV-B), associated with colony declines, as well as nine other viruses present in our samples. We found active replication of six V. destructor-associated viruses, including a novel virus, Varroa destructor virus 9 (VDV-9), and replication of two honey bee associated viruses, including both DWV-A and -B genotypes, suggesting that mites are biological vectors for important bee pathogens. We show that the antiviral RNAi response can be used define the host range of viruses in host-parasite interactions, such as honey bees and their parasites, enabling a better understanding of the role of a vector in the evolution and spread of honey bee pathogens.

genetics↗