Recent research suggests that pathogens can have profound effects on community structure. One such case is indicated by a series of empirical and modeling studies that suggests barley yellow dwarf viruses (BYDV's) could be responsible for the conversion of California's native perennial grasslands to exotic annual grasslands. Few studies, however, have addressed the role of BYDV's in the invasion of native perennial grasslands by invasive perennial grasses, as is common in California coastal systems. Coastal grasslands host their own unique vectors and vector-specific BYDV strains. I ask how common coastal native and invasive perennial grass species affect the growth and reproduction of the aphid vector species Sitobion avenae, and how effective S. avenae is at acquiring BYDV from those common species and transmitting BYDV to those common species using a series of greenhouse and laboratory manipulations and RNA extraction and RT-PCR for virus diagnosis. I also test how the density of Holcus lantaus, an invasive grass species that provides late season habitat for S. avenae, affects prevalence of BYDV in the two most abundant native grass species with field tissue collection and laboratory diagnosis.
Results/Conclusions
Results suggest that S. avenae prefer to feed on the native species regardless of their previous host species. Native grass species, however, are less susceptible to BYDV infection both in the controlled greenhouse experiments and in ambient field measurements, though H. lanatus presence does increase incidence of BYDV in the focal native grass species. These findings indicate that we need to understand the direct and indirect effects of BYDV transmission to fully understand native-invasive grass dynamics in the California coastal prairie system.