Den svarthuvade snigelns (Krynickillus melanocephalus) substratpreferens vid äggläggning

Sammanfattning: Krynickillus melanocephalus was first seen in Sweden 2015. It is now labeled as an invasive species and it potentially poses a threat to the ecosystem, but the slug has not yet shown to have great negative impact in gardens and agricultural fields. There is limited ecological knowledge about the species. This study aims to increase the knowledge about habitat preference of the species during oviposition. Fifty slugs were placed in experimental arenas containing four compartments, each containing a different substrate: birch leaves, gravel, potting soil and sphagnum moss. The position of the slugs were recorded daily for three consecutive days. Further, position of laid eggs were recorded at two different times. Slugs showed a preference for leaves at oviposition, and 88 % of the eggs were laid in this substrate, and the fewest eggs were laid in moss (0,6 %). The slugs were found the most in contact with the leaves. The result has expanded our knowledge about the species, which is important to develop ways to hinder and slow down its invasion. Future research about substrate preference in this species should focus on how humidity and temperature may affect the substrate preference, as well as on movement behaviour during oviposition, perhaps by means of PIT telemetry. The study provides practical advice regarding how to deal with garden waste in areas that are inhabited by the species, where, in particular birch leaf compost should not be moved around.