Un-muddying the waters: associations between soil properties and Galba truncatula presence on farmland, with implications for fluke control

Abstract The mud snail Galba truncatula is the primary intermediate host of Fasciola hepatica and Calicophoron daubneyi in Europe. Understanding its ecology is essential for identifying farm risk areas and preventing infection. However, the role of soil properties in determining suitable habitats is currently not well understood. This study surveyed 146 water-saturated habitats on 16 Welsh farms to examine the association between soil characteristics and G. truncatula presence. Habitats were searched for G. truncatula , habitat features were recorded and soil cores were analysed for pH, organic matter (OM) and texture (clay, sand, silt). Generalized additive models were used to identify soil factors that were significantly associated with the predicted probability of G. truncatula presence. The log ratio of clay vs (silt plus sand) was found to have a significant positive association, likely due to smaller, denser particles resulting in poorer drainage. The association between soil pH and G. truncatula presence was non-linear, where the likelihood of presence decreased below a threshold of 5.51, and above which limited effects were observed. Soil OM was significantly negatively associated with G. truncatula presence, a finding that may be the result of multifaceted interactions between OM and oxygen, calcium and dietary algal availability. These results demonstrate that soil properties play a significant role in determining G. truncatula habitat suitability beyond moisture availability. Soil properties should therefore be considered when developing land management and grazing strategies to sustainably control fluke and when spatially assessing fluke transmission risk and developing farm-level fasciolosis risk models.