Research Objectives

• Develop general mathematical theory to examine the joint effects of host community structure and resource supply to the hosts on generalist vector-transmitted pathogens.
• Parameterize the models we develop with data on native and introduced grasses in Pacific grasslands to predict effects of global change on disease dynamics.
• Test the model predictions using field experiments in north-central California and Corvallis Oregon.

Study Species

Collaborators

The pacific coastal grasslands are classic examples of biological invasions. The native perennial grasses have been almost completely displaced by introduced annual grasses, visible in the foreground.

I am collaborating with a group of six theoreticians and grassland ecologists to predict the effects of environmental change and host diversity on the dynamics of insect-vectored generalist pathogens. We are developing mathematical theory of generalist vector-transmitted pathogens that explicitly incorporates host competition for abiotic resources. We are testing the predictions of this theory using geographic-scale field experiments in Mediterranean-type grasslands with an aphid-vectored plant virus, barley yellow dwarf (BYDV). The experimental sites are on a precipitation gradient. We are specifically interested in the changes in the host community driven by the historical replacement of native perennial grasses by introduced annuals. We hypothesize that annual and perennial grasses may have complementary effects on pathogen persistence in the system. Our ultimate goal is to develop a general theoretical framework to predict the effects of human activities on a variety of host communities and pathogens. This project was funded by the NSF Ecology of Infectious Disease program through 2010.