Daniel J Leybourne 

Cereals are some of the most important global crops that contribute directly and indirectly to the production of food for human consumption. Cereal aphids can cause significant damage to wheat, barley, and oats, particularly via the transmission of plant viruses that cause devastating plant diseases, such as yellow dwarf disease. Yellow dwarf disease is caused by two related viruses within the Luteoviridae: Barley Yellow Dwarf Virus (BYDV, Luteovirus) and Cereal Yellow Dwarf Virus (CYDV, Polerovirus). High levels of yellow dwarf disease infection can result in yield losses of c. 20%, rising to 80% if infection is high. There are multiple B/CYDV species, some B/CYDV species are primarily vectored by one aphid species whereas others can be transmitted by multiple vectors.

Biological diversity within a given vector species (e.g., genotype, biotype) can influence virus transmission efficiency. However, it is unclear what biological factors drive this variation within a given vector species. Understanding how biological variation in vector populations influences virus transmission efficiency can help to identify biological traits that underpin successful transmission in competent vector populations. Here, the available literature on B/CYDV transmission efficiency is synthesised and significant variation in B/CYDV transmission efficiency is detected between different populations for several vector species. Three biological mechanisms that potentially underpin this variation are proposed.