Viral transmission dynamics during pollination: A temporal assessment of RNA viral transmission associated with honey bees (Apis mellifera) and almond pollen during a mass monoculture bloom

California is renowned for its robust agricultural landscape, producing 80% of the global almond supply and nearly all domestic almonds. This requires pollination services from over 60% of nationwide commercial migratory honey bee operations to meet production demands.
The Western Honey Bee (Apis mellifera) is the preferred pollinator of almonds in industrial agriculture. However, in 2025, honey bees are estimated to have experienced a 70% overwintering loss, drastically higher than the 40%-50% losses seen in previous years. Compounding stress, including that caused by pathogens leading to disease, can have negative impacts on overall honey bee health and contribute to colony loss. Some known RNA viral pathogens infecting bees include: Sacbrood Virus (SBV), Deformed Wing Virus (DWV), and Kashmir Bee Virus (KBV).
RNA viruses have high mutation rates, which creates the possibility for rapid adaptation to facilitate spillover to new species of bees and the potential for cross-kingdom spillover. Interestingly, both honey bees and plants are infected by a number of single-stranded RNA viruses. Insect-infecting viruses can be pollen-associated, as seen in pollens' capacity to vector (DWV) between infected and susceptible hosts via pollination.
Little is known about the pollen virome, its mechanisms for interspecies transmission, or to what extent pollinators and plants share viruses. This work aims to advance our understanding of the almond pollen virome and its potential for transmitting known viruses between plants and pollinators.