Multihost saprobes are facultative pathogens of bullfrog Lithobates catesbeianus eggs

Abstract

Pathogens that infect more than one host species create complex linkages in ecological communities. We tested whether saprobes that grow on multiple host species in aquatic systems can be facultative pathogens of amphibian eggs. We isolated oomycetes from dead arthropods, vertebrates, plant leaves, and frog eggs that coexisted in a small pond. Analysis of internal transcribed spacer regions of rDNA (ITS1-5.8S-ITS2) indicated that several of the strains colonized more than one substrate, including bullfrog Lithobates catesbeianus eggs. In a controlled experiment, isolates from 7 different host species were pathogenic to L. catesbeianus eggs. These results demonstrate that dead organisms can serve as reservoirs for facultative pathogens. © Inter-Research 2012.