Viruliferous and nonviruliferous bird-cherry oat aphids exhibit differential responses to Barley yellow dwarf virus-infected plants

Barley yellow dwarf virus (BYDV) causes one of the most devastating diseases of cereals worldwide. BYDV is transmitted by aphids in a persistent circulative manner. The bird-cherry oat aphid (BCOA), Rhopalosiphum padi (L.), is an important vector of BYDV-PAV. Increased understanding of virus, plant, and vector interactions could improve disease management. Recent research showed nonviruliferous BCOA prefer BYDV-infected compared to virus-free wheat and changes in virus-induced volatiles of plants mediate this response. Our objective was to examine simultaneously host plant preferences of viruliferous and nonviruliferous aphids. Assays were conducted using winter wheat plants (var. Lambert) that were inoculated with BYDV (using viruliferous aphids) or sham inoculated (using nonviruliferous aphids). Plants were seeded simultaneously and bioassays conducted 40-46 days after inoculation. Aphids were exposed to the entire suite of host plant selection cues during bioassays. Viruliferous and nonviruliferous aphids were released simultaneously into separate arenas containing a single leaf attached to an intact plant from each plant-inoculation treatment, and monitored every 12-hrs for 72 hrs. The proportion of aphids responding to each plant treatment were examined using the GENMOD procedure with a binomial distribution and logit link transformation in SAS. Nonviruliferous aphids showed a significant preference for BYDV-infected plants compared to viruliferous aphids while viruliferous aphids significantly preferred virus-free plants compared to nonviruliferous aphids. This shift in preference from infected to noninfected plants following virus acquisition could accelerate the rate of virus spread. Ongoing work aims to determine the mechanisms causing these changes in aphid behavior and implications for virus spread.