Ivana Majić

Between July and September 2021, researchers collected 100 specimens of the Spanish slug, Arion vulgaris, and dissected their cadavers to examine them for parasitic nematodes. Molecular techniques were used to identify the nematodes, which confirmed the presence of Oscheius myriophilus, marking the first recorded instance of this nematode in a gastropod host. To test the virulence of Slovenian strains of O. myriophilus and Phasmarhabditis papillosa and their effects on the feeding behavior of the Spanish slug, grey field slug (Deroceras reticulatum), and vineyard snail (Cernuella virgata), laboratory bioassays were conducted using nematodes grown in vivo. Nematodes were applied at various doses ranging from 10 to 500 nematodes/gastropod. The results showed that O. myriophilus and P. papillosa caused significant mortality (82.5% ± 2.5% at 15 °C) of the Spanish slug while being less effective against the vineyard snail and grey field slug. Nematodes were more virulent at a lower temperature (15 °C) than at the higher temperature (20 °C) tested in the experiment. Additionally, both nematode species significantly reduced gastropod herbivory. The potential use of O. myriophilus and P. papillosa as biological control agents against gastropods is discussed.