Metabolite-Based Resistance in Wheat Varieties to Aphid Virus Vectors: Progress and Future Opportunities

Cereal aphids Sitobion avenae and Rhopalosiphum padi are vectors for the barley yellow dwarf virus (BYDV) which, in addition to direct aphid damage, causes severe yield loss in wheat. Insecticides have commonly been used to control these pests. The advent of insecticide resistance spreading across aphid populations and the push to reduce insecticide use, however, requires new approaches to control aphid numbers. Screening studies have identified wheat varieties with natural product-based aphid resistance, which can act as an alternative to insecticides. Resistance induced by natural products include volatile organic compound-mediated (antixenotic) and development-modifying (antibiotic) processes. Full characterisation of these resistance mechanisms is still required and associated challenges, such as the influence of biotic and abiotic interactions, need to be addressed prior to their implementation into integrated pest management (IPM) or engineered into modern elite wheats. In this review, current literature on natural product-based S. avenae and R.padi resistance in wheat is discussed, outlining current knowledge gaps and challenges and highlighting future work required.