A modelling framework to estimate vector dispersal and disease spread in an important agricultural pathosystem
Cereals are some of the most agriculturally important crops grown worldwide. Cereal aphids are small sap-feeding insects that infest cereals and vector devastating cereal pathogens, principally the yellow dwarf viruses, with severe infection reducing yields by 20 - 80%. Currently, farmers are advised to apply insecticide if a single cereal aphid is found within the crop. However, this is an oversimplification of the biology and ecology of the vector-virus system: Each aphid species can transmit a range of yellow dwarf virus species with variable efficiency, and intra-species diversity within a vector species (genotype) can influence this further. Accounting for this variation in decision-making processes has the potential to help with developing bespoke management options based on the composition of the local vector-virus population, and represents a novel avenue that could be explored to develop more sustainable management strategies. Here we describe a stage-structured model that can estimate vector dispersal and disease spread. We use data for the two main cereal aphid species and the two yellow dwarf virus species of greatest concern in Europe to examine how diversity at each level of the vector-virus system impacts disease spread. More broadly, our modelling framework represents a tool that can be used to explore vector-virus-host interactions in greater detail, and we use cereal systems as a case study. Our modelling scenarios highlight diversity at each scale as an important factor. We show that the two main vector species have contrasting dispersal patterns, and that this interacts with virus transmission efficacy to influence disease spread; genetic variation within a vector population is a key driver behind disease spread and disease risk; and for vector species that transmit multiple virus species, the specific vector-virus species combination is a key risk factor to consider.