Environmental DNA-derived pathogen gene sequences can expand surveillance when pathogen titers are decoupled in eDNA and hosts

Abstract

Environmental DNA (eDNA) collection has emerged as a powerful and noninvasive wildlife population and pathogen-monitoring tool. Ranavirus is an emerging pathogen linked to die-offs in amphibian species. Applications of eDNA detection for ranavirus surveillance have shown promise, but it is unclear how reliably eDNA represents viral pressure on host populations. We evaluated the relationship of ranavirus titers in hosts and eDNA in four New York vernal pools from May to October 2016. We compared ranavirus titers in aquatic eDNA samples (n = 562) and liver samples (n = 362) of wood frog (Lithobates sylvaticus) and green frog (Lithobates clamitans) larvae from pools with past ranavirus die-offs. We detected low-quantity Ranavirus DNA (