The impact of axenic strains of fungi and oomycetes on the preference of Gammarus roeselii for leaf litter

摘要: The interaction of microbial colonization with leaf litter breakdown by the shredder Gammarus roeselii was studied in littoral large Lake Constance. In a first step we selective feeding gammarids on from three different treatments. Littoral exposed, tap water and autoc1aved leaves were offered to G. standard food-choice assays under laboratory conditions. We found highly exposed indicating that conditioning is 'affecting shredders behaviour. Neither C, N, P nor protein ergosterol content positively correlated relative consumption rates leaves. For more detailed study oomycetes fungi iso­ lated Based sequence internal transcribed spacer (ITS) regions rDNA, identified single strains Fusarium sporotrichoides, Microdochium sp., Ascomycete Cylindrocladiella parva; two Cylindrocarpon sp.; Pythium sp. Subsequently, food choice conducted using isolated offering autoclaved colonized strain. Three (c. parva, 94-2057 sp.) preferred roeselii, while F. sporotrichoides avoided. Leaves each oomycete isolates (Pythium neither pre­ ferred rejected roeselii. Our results suggest behaviour affected abundance specific fungal strains. Thus, whether acts as repellent or an attractor for depends community