Epidemiology of Barley Yellow Dwarf: A Study in Ecological Complexity

Abstract

Most pathosystems encompass intermeshed biological relationships between a pathogen and its hosts in a shared environment. If additional biological entities such as vectors of the pathogen are integral components, as with many plant virus systems, the complexity increases substantially. When the virus is widespread in several crop and perennial plant species, has a number of distinct variants, or the variants are spread selectively by several vector species, the complexity of the ecological interactions is even greater. All of these elements, when interacting concurrently, create exceptionally complex ecological pathosystems. The disease complex known as barley yellow dwarf epitomizes such systems. Investigating virus variants, their plant hosts and vectors, and elucidating the confounding resultant interactions in diverse and fluctuating environments in different regions of the world is an extremely difficult task, but one that must be undertaken to gain an understanding of the pathosystem. To do so