Using an interdisciplinary approach to understand dynamics of pollen-borne viruses in peach orchards

Pollen-mediated virus transmission is an important but understudied area that poses significant challenges to the stone fruit production. Prunus necrotic ringspot virus (PNRSV) and prune dwarf virus (PDV) are pollen-borne ilarviruses affecting key stone fruit crops, including peaches, which can result in substantial yield losses. However, the role of pollinators in the dispersal of these viruses under orchard settings remains poorly understood. Our two-year survey of peach orchards revealed that bees carry PNRSV and PDV-positive pollen during bloom and move along orchard blocks. Interestingly, virus detection in bee pollen samples was consistent with the infection levels in respective orchard blocks, suggesting that virus-infected trees may act as an important source of inoculum for secondary spread. Since PNRSV is also present in wild Prunus spp. at the orchard borders, we further explored whether bees contribute to virus movement at the wild cherry-cultivated peaches interface. Both peach and wild Prunus pollen were consistently found in bee-collected samples throughout the bloom period. Interestingly, the odds of detecting PNRSV were about 7.8 times higher when wild Prunus pollen was present compared to when it was absent. Several bee genera, including Andrena, Bombus, and Habropoda, carried both peach and wild Prunus pollen during early and late bloom. Together, these results advance our understanding of pollen-borne virus ecology and have considerable implications for the management of pollinators and virus-inoculum sources to preserve orchard health.