Grassland parasites and community dynamics under climate change

Global warming is affecting a wide range of organisms, including parasites of plants and animals. Most studies of the biological effects of climate change, however, consider physiological processes and single species responses, despite the fact that inter-species interactions are known to strongly influence outcomes of climate change at community level. This limitation could undermine predictions of future impacts of parasites on natural and agricultural ecosystems. This project will investigate how linked species in grassland-soil communities are affected by climate change, and how outcomes are influenced by interactions between species. This will enhance understanding of the effects of climate change on grazing system productivity and resilience. The project will focus on nematodes, which are major parasites of grazing livestock, and of grass itself. With rising anthelminthic resistance, the agricultural industry is looking towards more holistic strategies to alleviate infection pressure, and these will benefit from better understanding of the ecological context of parasite transmission.

The specific aims of this project are to investigate how biotic interactions alter nematode parasite transmission in different grassland communities. This will be addressed using a combination of mesocosms, altered in situ environment experiments, and predictive modelling. Once key interactions have been determined, the project will investigate how they are affected under climate change. The impact of abiotic factors such as temperature and moisture will be considered in both their direct impacts, such as parasite thermal responses, and their indirect impacts through community interactions.

The general approach will be to: (i) calibrate thermal response curves for key species in each functional group (including plant-parasitic and animal-parasitic nematodes, grass, and grazers); (ii) compare curves and identify 'winners and losers' under elevated temperature scenarios; and (iii) run dynamic models to compare outcomes under seasonally varying climates and climate change. Existing data on the climate-dependence of these groups will underpin model calibration and validation, complemented by additional experiments as needed. Following calibration, models will be tested and validated against longitudinal data on species responses under baseline and warmed field conditions. Work will be based primarily at Queen's University Belfast and CASE partners, the Agri-Food and Biosciences Institute (AFBI).

Project results will enhance understanding of how the effects of different thermal responses among species in ecological communities are modified by the linkages between them to determine net impacts on ecosystem function. Outputs will illustrate how non-linear responses to climate change might affect natural and managed grassland systems. Model sensitivity analysis will map key species responses and vulnerabilities within the system, and support rational prioritisation of areas for future research. Scenario analysis will explore likely responses in terms of the stability and productivity of natural grassland systems, and rational adaptive management on livestock farms. Consequences of parasite adaptation to warming could also be explored through the model, and response curves compared among populations from different climatic zones.

This project has potential benefits for the agricultural industry, by underpinning the design of more sustainable and resilient parasite control in grazing systems. Alleviation of reliance on chemical treatment of nematodes would slowing the development of resistance and hopefully provide alternative control options for farmers. This will benefit consumers, by helping to provide affordable food with decreased environmental impacts.