Diversity-disease relationships in natural microscopic nematode communities

Abstract

High host biodiversity can reduce parasite prevalence, a phenomenon widely studied in macroscopic organisms and termed the ‘dilution effect of disease’. Data from host-parasite dynamics in microbial communities is lacking but is essential to assess the stability of microbial communities under global change. Here, we study diversity-disease effects in wild nematode communities by profiting from the molecular tools available in the well-studied model nematodeCaenorhabditis elegans. Nanopore sequencing was used to characterize nematode community diversity and composition whereas parasites were identified using experimental assays based on fluorescent staining or fluorescent reporter strains. Our results indicate biotic stress is abundant in wild nematode communities. Dilution-disease effects were observed based on the presence of microsporidian parasites and by activation of the Intracellular Pathogen Response. Together, this provides the first demonstration of diversity-disease effects in microbial communities and establishes the use of nematode communities as model systems for disease dilution.