Abstract
Environmental DNA (eDNA) surveying has potential to become a powerful tool for sustainable parasite control. As trematode parasites require an intermediate snail host that is often aquatic or amphibious to fulfil their lifecycle, water-based eDNA analyses can be used to screen habitats for the presence of snail hosts and identify trematode infection risk areas. The aim of this study was to identify climatic and environmental factors associated with the detection of Galba truncatula eDNA. Fourteen potential G. truncatula habitats on two farms were surveyed over a 9-month period, with eDNA detected using a filter capture, extraction and PCR protocol with data analysed using a generalized estimation equation. The probability of detecting G. truncatula eDNA increased in habitats where snails were visually detected, as temperature increased, and as water pH decreased (P < 0.05). Rainfall was positively associated with eDNA detection in watercourse habitats on farm A, but negatively associated with eDNA detection in watercourse habitats on farm B (P < 0.001), which may be explained by differences in watercourse gradient. This study is the first to identify factors associated with trematode intermediate snail host eDNA detection. These factors should be considered in standardized protocols to evaluate the results of future eDNA surveys.
Highlights
Environmental DNA surveys have become powerful tools to identify and monitor the presence of species in aquatic environments (Thomsen and Willerslev, 2015)
221 samples were collected across 14 habitats during the study, 48% of which were positive for G. truncatula Environmental DNA (eDNA)
The successful application of eDNA analyses on farms requires an understanding of the dynamics of eDNA concentration across space and time and how these interact with local environmental factors (Harrison et al, 2019)
Summary
Environmental DNA (eDNA) surveys have become powerful tools to identify and monitor the presence of species in aquatic environments (Thomsen and Willerslev, 2015). Water-based eDNA analysis techniques have been developed and applied to detect rare and invasive species and infectious pathogens in aquatic environments, which have led to changes in policy and management (Bass et al, 2015; Thomsen and Willerslev, 2015). Recent research has identified spatial patterns in trematode parasite eDNA with the aim of informing strategies to reduce transmission (Hashizume et al, 2017; Sengupta et al, 2019) and to evaluate parasite infection intensity in host populations (Huver et al, 2015). Identifying areas where these intermediate snail host species are present is essential to evaluate trematode epidemiology and inform control strategies
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