Association of slugs with the fungal pathogen Epichloë typhina (Ascomycotina: Clavicipitaceae): potential role in stroma fertilisation and disease spread

Epichloë spp. are endophytes of grasses, and form epiphytic external stromata on flowering tillers. E. typhina was first noticed infecting Dactylis glomerata (= orchardgrass, cocksfoot) stands in the Willamette Valley in 1996, and soon became the primary factor limiting the longevity of seed production fields. Several species of slugs are present in these fields, and we investigated their role in E. typhina biology. Pre‐dawn surveys of D. glomerata fields in 2009 and 2010 found Prophysaon andersoni and Arion subfuscus slugs feeding on the fungal stromata. When unfertilised and fertilised immature stromata predominated, approximately 80% of the individuals of these two species that were seen on plants were found on the stromata. As the majority of stromata reached maturity the presence of these species on stromata declined to between 20–40%. The common agricultural slug pest, Deroceras reticulatum, was on stromata only 20% of the time early in the season, and declined to