Acquisition of Barley yellow dwarf virus alters host plant preferences of its aphid vector

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 prefers BYDV-infected compared to virus-free wheat and changes in virus-induced volatiles of plants mediate this response. Our objective was to evaluate simultaneously host plant preferences of viruliferous and nonviruliferous aphids, examining direct vs. indirect effects of virus acquisition. Two acquisition methods, feeding from plants and membrane feeding, were used to produce the viruliferous and nonviruliferous aphid treatments used in the bioassays. Choice tests were conducted using winter wheat plants (var. Lambert) that were inoculated with BYDV (using viruliferous aphids) or sham inoculated (using nonviruliferous aphids). 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 for 72-hrs. The proportions of aphids responding to the BYDV-inoculated plant treatment and the sham-inoculated plant treatment were examined using the GENMOD procedure (binomial distribution, logit link transformation) in SAS. Nonviruliferous aphids significantly preferred BYDV-infected plants, while viruliferous aphids significantly preferred virus-free plants. 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.