Garden Gastropods : using citizen science to understand the diversity, role and impact of slug and snail species in British gardens

Abstract

Slugs and snails are important horticultural pests. However, little is known about the diversity of slug and snail species in British gardens and which species were responsible for causing damage to plants or which may be beneficial. This project sought to fill this information gap by using citizen science and laboratory studies to understand more about the slugs and snails found in British gardens. A range of slug and snail species were tested in the laboratory to identify which are damaging to Hosta plants. Large omnivorous species contributed the most damage, with other slug and snail species demonstrating a preference for senescent material. An assortment of refuge trap materials with bait were tested in the field to identify which were most effective at detecting slug and snail species. Little difference was found between material types, with presence of bait attracting the most slugs and snails. The RHS Cellar Slug Survey asked members of the public to submit records of the declining Limacus flavus and expanding Limacus maculatus. L. maculatus was found to be widespread and dominant, while L. flavus was rarely encountered with an irregular geographic distribution. The Slugs Count project recruited 60 volunteers from across mainland Britain to carry out systematic surveys of slugs in their gardens for a full year. Over 22,700 slugs were collected and identified by participants, with 97% of these received and verified in the lab. Participants were found to overestimate species richness 60% of the time. This study shows there has been wide scale change in the British garden slug fauna since the last detailed study in the 1940s (Barnes & Weil, 1944 & 1945), with non-native species becoming increasingly dominant in our gardens. Potential implications to ecosystems and the likelihood of further slug introductions due to increased trade and climate change are discussed.