IRFP: Exploring the Impacts of Human Land Use on Parasite Transmission Dynamics in a Dung Beetle-Fecal Helminth Model System

Nichols Elizabeth S, New York NY

Investigators

Abstract

The International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad. This award will support a twenty-four-month research fellowship by Dr. Elizabeth Nichols to work with Prof. Kenneth Wilson at Lancaster University, Lancaster UK. Biotic interactions between parasitic and free-living taxa are fundamental to a range of ecosystem processes, including the mediation of parasitic disease transmission between species in a community. Parasites with complex life-cycles (e.g. helminthes (parasitic worms)) exert enormous fitness and economic costs on humans and livestock across the global tropics. However how environmental change affects the biotic interactions involved in parasite transmission remains poorly understood. The proposed project seeks to develop a novel dung beetle - fecal helminth model system to tease apart the mechanisms by which land-use change influences parasitic disease transmission, by impacting interactions between free-living species and parasitic helminths. As many dung beetles species broadly use the feces of different mammal species, beetle communities in tropical agricultural landscapes commonly interact with fecal helminths (parasitic worms) of two distinct transmission strategies: the fecal-oral helminths of wild and domestic herbivores, and the trophically transmitted helminths of wild and domestic carnivores (when they eat the adult beetles). Preliminary data indicates that dung beetle feces processing often decreases the rate of successful transmission for fecal-oral helminths, yet increases the transmission of trophic transmissions helminths, for which beetles commonly act as intermediate hosts. These strikingly different outcomes suggest that land-use changes that alter dung beetle community diversity may simultaneously suppress and maintain or amplify disease transmission across different mammal host species. In addition, the magnitude and direction of these effects may be predicted by a small set of dung beetle species' traits. This project combines field, experimental and modeling approaches to characterize the mechanistic relationships between dung beetle community regulation of parasite transmission, and the impacts of land-use change on transmission dynamics. At a basic level, the research will (1) enhance our understanding of the mechanisms underlying transmission dynamics and their response to land-use change, and (2) contribute to the development of a novel model system that can expands upon extant single-microparasite transmission models to assess how multiple complex life-cycle parasite species respond changes in free-living species diversity. The economic and health impacts of helminths (parasitic worms) in tropical agricultural landscapes are tremendous. At an applied level, this work will provide useful information on how environmental change in agricultural areas influences those species interactions tightly linked to ecosystem service outcomes, such as reduced disease transmission. In addition to these benefits, this research will help develop new international collaboration between the PI and research groups at Lancaster University, Lancaster UK, the Federal University of Lavras, Lavras Brazil, the University of São Paulo, São Paulo, Brazil, Barnard College, New York, USA, and the American Museum of Natural History, New York, USA.