Infections of a single host by multiple pathogens are common in nature but relatively poorly studied compared to single infections. In potatoes and other solanaceous plants, coinfection by multiple strains of Potato virus Y, an insect-transmitted plant virus, has resulted in the emergence of damaging recombinant strains in recent decades. These emerging viruses have adapted rapidly to agroecosystems and dominated virus populations over extensive geographical areas. Our research is focused on understanding the ecological factors that allow recombinant virus strains to emerge, spread rapidly, and become dominant. We have investigated the drivers of virus emergence at multiple scales, within landscapes, within fields, within individual hosts, and within vectors.
Results/Conclusions
We find that landscape composition and structure, vector community composition, transmission dynamics, and within-host processes all influence virus epidemiology and the prevalence of both parental strains and recombinant strains. Compared to more heterogeneous landscapes, simplified agricultural landscapes are associated with higher virus prevalence, virus amplification, and dominance by recombinant strains. Within hosts, virus strains co-localize in single epidermal leaf cells, where recombinant strains tend to outcompete parental strains. Within vectors, when more than one strain is acquired, recombinant strains are transmitted preferentially over parental strains regardless of the order they were acquired. Agricultural management practices, such as removing plants with severe disease symptoms, also select for recombinant viruses. Taken together, these processes operating at multiple scales help to explain the rapid rise of recombinant strains in this disease system.