The effects of generalist pathogens on hosts in a community context will be mediated both by epidemiological traits (e.g. vector preference) and variation among host species in traits such as resistance and tolerance to infection. The dilution hypothesis suggests that host community composition can alter the prevalence of a generalist pathogen, and therefore its importance on host fitness. Specifically, when hosts that are highly competent pathogen reservoirs are grown with less competent hosts, the presence of the less competent host(s) could slow the spread of the pathogen through the more competent host as well. To test the dilution hypothesis, we grew bi-cultures of eight annual grass species that are hosts to the vector transmitted generalist barley yellow dwarf virus (BYDV) in mesocosms exposed to or protected from viral inoculation. All of these simple communities consisted of the most competent host, Avena fatua, and other hosts that vary in their competence.
Results/Conclusions
