Impact of natural vegetation on barley yellow dwarf virus (BYDV) epidemiology

The cereal aphid-borne barley yellow dwarf virus (BYDV) is a significant threat to small grains worldwide, with the BYDV-PAV strain being particularly damaging in the United States. The bird cherry-oat aphid, Rhopalosiphum padi L. (Hem., Aphididae), is the most efficient vector of BYDV-PAV. Bird cherry-oat aphids and BYDV are known to colonize a broad range of annual and perennial grassy hosts, including small grains and forage crops such as tall fescue (Festuca arundinacea). The most commonly planted tall fescue in the US hosts the endophytic fungus Epichloë coenophiala. Although this relationship enables the perennial forage crop to withstand biotic and abiotic stresses, the “common tall fescue” is also known for its toxicity to livestock. The “novel endophyte” varieties have been developed and promoted to reduce the toxic effects on animals. However, little is known about how replanting common toxic tall fescue with novel endophyte varieties could impact aphid-plant-BYDV interactions and, subsequently, BYDV epidemiology. The present greenhouse study compares aphid preference for, performance on, and BYDV transmission success from different types of tall fescue to winter wheat. Our initial results suggest that the aphids prefer wheat over the novel endophyte and the endophyte-free tall fescue types. The aphids, however, did not show any preference between the common toxic tall fescue and wheat. Aphid reproduction and transmission bioassays are ongoing, and results will be presented and discussed. The findings will shed light on the ecological implications of grazing land management practices or BYDV epidemiology and contribute to sustainability in integrated production systems.