D3510: Field phenology and virus transmission from blueberry aphids in Oregon

The appearance and spread of a blueberry virus complex in the Pacific Northwest was documented in 2022 and 2023, comprising Scorch (BlScV, Carlavirus), blueberry virus-L (BlVL, Luteovirus), and Blueberry virus-S (BlVS, Carlavirus). The mechanisms and vectors of transmission of these viruses remain undefined, but based on other crop systems and preliminary studies, it is hypothesized that these viruses are transmitted by winged adults of blueberry aphids. The detailed phenology of the life stages of blueberry aphids and virus infection rates is currently unknown in Oregon; it is unclear when winged adults are more abundant in blueberry fields, and therefore more likely to transmit viruses. It is also unknown which aphid species present in blueberry fields transmit these viruses. We sampled aphids weekly in five blueberry fields in the Willamette Valley of Oregon through visual search and pan trapping. Using RT-PCR, aphid samples were tested for the presence of all three viruses, and identified to genus using morphological characteristics. Preliminary results from late summer 2023 showed that BlVL was prevalent in approximately 40% of aphid samples collected, but BlSc and BlVS was not detected in aphids. Furthermore, we found six different genera of aphids from pan traps in blueberry fields. Here we also report aphid phenology and virus infection rates from 2024 monitoring. These results help elucidate the ecology and management of virus vectors in blueberry farms in Oregon.