Consequences of the colonisation of leaves by fungi and oomycetes for leaf consumption by a gammarid shredder

摘要: Summary 1. Leaf litter breakdown by shredders in the field is affected leaf toughness, nutritional value and presence of secondary compounds such as polyphenols. However, experiments involving use single fungal strains have not supported assumption that parameters determine food selection perhaps because a failure to test for high consumption prior isolation strains, overrepresentation hyphomycetes or potential effects accompanying bacteria. In this study, we used bacteria-free, actively growing fungi oomycetes isolated from conditioned which shredder had already shown rates. 2. Black alder (Alnus glutinosa) was exposed littoral zone Lake Constance autumn, subsamples were analysed Gammarus roeselii under standard conditions at regular intervals. On dates with rate leaves, 14 isolated, freed bacteria grown on autoclaved leaves. 3. Six eight measured leaves significantly correlated rates, colinearity among hampering identification causal relations between feeding activity. 4. When litter, toughness colonised always lower than control content protein, N P increased. There pronounced strain-specific parameters. Consumption rates also differed significantly, nine fourteen isolates consumed higher controls none proving be deterrent. Protein polyphenol rates. Oomycete-colonised similar but quality fungi-colonised leaves. 5. We argue direct attractant repellent G. roeselii are important. found indirect role operating via