Environmentally dependent host-pathogen and vector-pathogen interactions in the barley yellow dwarf virus pathosystem

1. Understanding environmentally dependent variation in interspecific interactions is needed for evaluating how agroecosystems respond to abiotic stressors, including climate change. Both biotic and abiotic conditions shape crop responses to stress events, but interactions between environmental conditions and insect borne plant pathogens remain poorly understood. 2. We tested the hypothesis that drought stress, as applied by experimental water deprivation, drives conditional outcomes in host–pathogen and host–vector interactions using a cereal–aphid–virus association and greenhouse experiments. 3. Under conditions of ample water supply, infection of wheat plants with Barley yellow dwarf virus (BYDV) resulted in reduced above-ground growth, seed set, seed yields and seed germination compared with plants exposed only to non-infected (non-viruliferous) aphids or control plants not subjected to aphid infestation. However, when water was chronically limiting, infection with Barley yellow dwa...