Yellow dwarf viruses: aphid transmission efficiency and cereal host range.

Abstract

Yellow dwarf viruses (YDVs) are transmitted by aphids and can significantly reduce grain yield in cereals worldwide. While barley yellow dwarf virus PAV (BYDV PAV) has long been present in Australia, the YDV species barley virus G (BVG) and barley yellow dwarf virus PAS (BYDV PAS) were reported for the first time more recently. Little data about the transmission and host range of BVG has been published worldwide, while epidemiological information about BVG and BYDV PAS in an Australian context is limited. Therefore, glasshouse experiments were conducted to examine the efficiency of the bird cherry-oat aphid (Rhopalosiphum padi), corn leaf aphid (Rhopalosiphum maidis), rose grain aphid (Metopolophium dirhodum) and Russian wheat aphid (Diuraphis noxia) to transmit BVG, BYDV PAS and BYDV PAV. BYDV PAS and BYDV PAV were transmitted at similar rates by each of the four aphid species. Although BVG was most efficiently transmitted by the corn leaf aphid, it was also transmitted, albeit less efficiently, by the bird cherry-oat aphid. Significantly, in our study, the corn leaf aphid transmitted BVG at a much higher rate (63%) using single-aphid inoculations than had previously been reported by others (7%). Varying levels of susceptibility were observed in host range experiments, and four additional BVG hosts were identified. Russian wheat aphid did not transmit any of the viruses examined. These results have implications for YDV management while also demonstrating the complexity and specificity of the relationships between YDVs, the aphids that transmit them and the plant hosts that they infect.