Phytophthora survives the digestive system of the invasive slug Arion vulgaris.
Decline of European beech (Fagus sylvatica) due to Phytophthora spp. has become an increasing problem in Europe, including Norway, the northernmost distribution of this beech species in the world. Observations of the invasive slug Arion vulgaris in a Phytophthora-infested beech forest in southeastern Norway, led to investigation of A. vulgaris as a potential vector for Phytophthora spp. Thus, the primary goal of this work was to reveal if Phytophthora plurivora and P. cambivora isolated from beech in Norway may survive passing through the digestive system of the slugs. The slugs were allowed to feed on hyphal mats of Phytophthora for 6 days. Faeces from the slugs were examined for the presence of mycelium using both light microscope and Phytophthora specific PCR (polymerase chain reaction). Faeces were also directly dropped or transferred onto Phytophthora selective agar to investigate if the hyphae were viable. The experiments showed that A. vulgaris slugs were capable of ingesting and excreting hyphae of P. cambivora and hyphae and oospores of P. plurivora. Hyphae from both species proved to be viable when faeces were excreted directly on the agar.