Temporal dynamics of trematode intermediate snail host environmental DNA in small water body habitats

Environmental DNA (eDNA) surveying has the potential to become a powerful tool for sustainable parasite control. As trematode parasites require an often aquatic or amphibious intermediate snail host to fulfil their lifecycle, water based eDNA analysis can be used to screen habitats for intermediate snail host presence and inform trematode infection risk areas. The aim of this study was to identify climatic and environmental factors associated with the detection of Fasciola hepatica intermediate snail host Galba truncatula eDNA. 14 potential G. truncatula habitats were surveyed over a 7-month period, with eDNA detected using a filter capture, extraction, and PCR protocol with data analysed using generalized estimation equation models.

G. truncatula eDNA was increasingly detected in habitats where G. truncatula were visually detected, as temperature increased, and water pH decreased (P < 0.05). Rainfall was positively associated with increased eDNA detection in watercourse habitats of a slight slope, whereas increased rainfall was associated with decreased eDNA detection in watercourse habitats with a steeper slope (P < 0.001). This study is the first to identify environmental and climatic factors associated with trematode intermediate snail host eDNA detection. The factors identified should be recorded and used to evaluate results of future eDNA surveys of small water body habitats.