Morphometric traits of shells determine external attack and internal utilization marks in the Roman snail in eastern Germany

Abstract

Abstract. Overexploitation, habitat destruction and a changing climate threaten populations of the Roman snail (Helix pomatia Linnaeus, 1758), which has led to a high protection status in Germany. Vertebrate and invertebrate predators, including parasites and facultative parasitoids, further cause pressure on populations. Given the conservation concern for H. pomatia and its rarity in the study region (Cottbus, Germany), we studied how predators and facultative parasitoids utilize H. pomatia shells with a focus on non-invasive field methods. As previous studies indicated that shell size may affect prey selection by predators, morphometric traits were measured in eight subpopulations. We identified the total number and percentage of H. pomatia shells that showed external attack marks by predators and internal utilization marks by Diptera pupae and related those utilization patterns to the morphometric traits of shells. A large proportion of the shells in local subpopulations showed signs of external attack and internal utilization, and both utilization forms were positively correlated. External attacks by predators were more frequent in larger shells and internal utilization by Diptera was more common in shells with higher body density. These results suggest a considerable pressure by predators and potential facultative parasitoids on H. pomatia populations in the study area. Future research should focus on the relationship between snails from the family Helicidae and flies from the genus Discomyza. Conservation programmes should consider abiotic habitat conditions together with potential trophic interactions to maximize the success of conservation strategies.

Exploring the predation of large land snails using preyed shell remains from rock anvil sites in a tropical limestone rainforest in Malaysia

“…This non-invasive method for studying predation could have a lot of potential, but it also has its limitations ( Tluste et al 2020 ). First, although the analysis of empty preyed shells is a powerful method, predators that eat the whole snail could be a problem for assessing selection by predators ( Němec and Horsák 2019 ).…”

“…It is known that the marks left by predators on the shells of marine and freshwater molluscs include injuries and scars at the aperture ( Ebbestad et al 2009 , Kröger 2011 ), on the shell whorls ( Dietl and Hendricks 2006 , Stafford et al 2015 , Sime and Kelley 2016 , Harper 2016 , Tluste et al 2020 ) and as boreholes ( Kowalewski 2004 , Sime and Kelley 2016 , Harper 2016 ). On the other hand, traces of predation on land snail shells include boreholes ( Liew and Schilthuizen 2014 ), remains of diptera pupae on the inside of the shell ( Tluste et al 2020 ) and breakage on the aperture and shell whorls ( Němec and Horsák 2019 , Hayashi and Sugiura 2021 ).…”

Sausage technology for food sustainability: recipe, color, nutrition, structure

“…Snails (land and freshwater) are a food product that can solve the problem of future global food shortages [47]. However, Roman and other edible snails are threatened with extinction in Europe due to overexploitation, habitat destruction, climate change, and the impact of predators and parasites [48]. To preserve snails in nature, it is necessary to expand their cultivation under Heliciculture conditions and investigate changes in natural and farm habitats [49].…”

Entomological Investigation of the Main Entomatic Adversities for Terrestrial Gastropods Helix aspersa Müller (Mollusca Gastropoda Pulmonata): A Preliminary Study in Sardinian Heliciculture Farms

“…The knowledge on the predatory arthropod fauna present in snail farms remains insufficient, and most of the studies have been carried out on specimens in the wild [ 12 , 13 ].…”

“…Some of these studies carried out on other species of snails have analyzed the lesions present on the shells in an attempt to trace the predator [ 12 ]; to date, the extent to which predatory actions affect the snail population and the selection of prey by predators and parasites have not been confirmed [ 13 ]. Furthermore, there is a lack of specific data on the predatory species found in the Italian territory.…”