D3067: The role of flower-visiting insects in the spread of pollen-borne viruses in peach orchards

Prunus necrotic ringspot virus (PNRSV) and prune dwarf virus (PDV) are pollen-borne viruses of stone fruits, including peaches, which can cause substantial yield loss and orchard decline. PNRSV and PDV are predominantly transmitted through grafting and vegetative propagation, but in-orchard spread and seed transmission can also occur via pollen. Honeybees and thrips have been implicated in the horizontal transmission of PDV, PNRSV, and other related ilarviruses in other crops. Although both horizontal and vertical (i.e., seed) transmission of both viruses occurs through pollen, the role of flower-visiting insects in their transmission in peaches is not well understood. I hypothesize that major pollinators of peaches could facilitate the transmission of both viruses during pollination. To test this hypothesis, I set blue vane traps and blue sticky cards in healthy and virus-infected peach orchard blocks to capture flower-visiting insects for virus detection and to shortlist potential candidates. Preliminary data suggest that honeybees and carpenter bees are predominant pollinators of peach in South Carolina. Additionally, bees collected in this survey carry virus-infected pollen during bloom. Specifically, bees collected from PNRSV, and PDV infected blocks have been tested positive for the respective viruses in their pollen. Controlled greenhouse experiments will be conducted to understand the underlying mechanism in virus acquisition and localization, vector biology, and virus-vector-host interactions. Additionally, I will investigate the effect of dual PNRSV-PDV infection on pollen transmission and pollinator efficiency. Understanding the transmission and spread of peach viruses will be useful in developing sustainable strategies to manage viral diseases.