NERC-FAPESP: Revealing an invasive plant-mammal-disease vector system in São Paulo State, Brazil

Plant invasions can have wide-ranging ecological impacts on native communities and ecosystems. In southern Brazil, tall, herbaceous invasive plants such as white ginger (Hedychium coronarium) and elephant grass (Cenchrus purpureus) could alter the distribution and abundance of capybara (Hydrochoerus hydrochaeris) within landscapes, by providing refuge and resting habitat, and potentially, food. Capybara carry the tick Amblyomma sculptum which is the disease-vector of the bacterium Rickettsia rickettsii; the agent of often-fatal Brazilian Spotted Fever (BSF) in people. Thus, there is potential for the invasive plants to increase disease risk in invaded areas, but the strength of the relationships between invasive plants, capybara and ticks remains unquantified. Understanding these dynamics and their generality will have significant consequences for understanding spatiotemporal patterns of tick-borne disease risk in this region. This project's overarching goal is to describe and understand the putative invasive plant-capybara-tick system in São Paulo state, which will form the basis of further investigation and forecasting of the human health risks posed by this system and its component species. Our project will be supported by three workshops: two at the University of São Paulo and a final project partner workshop at Durham University. At the start of the project, Workshop 1 will establish a network of researchers and protected area managers in the state focused on monitoring Hedychium, Cenchrus and their interactions with capybara and ticks. This network will form the basis of a data collection campaign to establish the distribution of the invasive plants and capybara. We will use these distribution data to select sites for tick abundance sampling and camera trap surveys, in paired invaded and uninvaded vegetation, to test if tick abundance and capybara occupancy are higher in invaded areas. Capybara and tick data will be collected in the second half of the project, after Workshop 2, when we will provide training in camera trap methods to estimate capybara occupancy, initiate a pilot study to confirm evidence of capybara presence from vegetation features in drone images, and finalise tick survey methods. After field data collection and analysis, we will review our key findings in Workshop 3 at the end of the project, discuss lessons learned and develop targeted grant applications to expand the project. Our project will bring together a unique combination of skills and experience of the project partners to form the basis of a long-lasting UK-São Paulo state collaborative network, focused on systems-based research of the impacts of invasive species.