title: Stable isotope signatures reflect dietary diversity in European forest moths.
abstract: BACKGROUND
  Information on larval diet of many holometabolous insects remains incomplete. Carbon (C) and nitrogen (N) stable isotope analysis in adult wing tissue can provide an efficient tool to infer such trophic relationships. The present study examines whether moth feeding guild affiliations taken from literature are reflected in isotopic signatures.
  
  
  RESULTS
  Non-metric multidimensional scaling and permutational analysis of variance indicate that centroids of dietary groups differ significantly. In particular, species whose larvae feed on mosses or aquatic plants deviated from those that consumed vascular land plants. Moth δ(15)N signatures spanned a broader range, and were less dependent on species identity than δ(13)C values. Comparison between moth samples and ostensible food sources revealed heterogeneity in the lichenivorous guild, indicating only Lithosia quadra as an obligate lichen feeder. Among root-feeding Agrotis segetum, some specimens appear to have developed on crop plants in forest-adjacent farm land. Reed-feeding stem-borers may partially rely on intermediary trophic levels such as fungal or bacterial growth.
  
  
  CONCLUSIONS
  Diagnostic partitioning of moth dietary guilds based on isotopic signatures alone could not be achieved, but hypotheses on trophic relationships based on often vague literature records could be assessed with high resolution. Hence, the approach is well suited for basic categorization of moths where diet is unknown or notoriously difficult to observe (i.e. Microlepidoptera, lichen-feeders).
authors.affiliation: Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, 1030 Vienna, Austria.
authors.forename: Marc-Oliver
authors.initials: MO
authors.lastname: Adams
authors.affiliation: Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, 1030 Vienna, Austria ; Biology Center, Institute of Entomology, University of South Bohemia and Czech Academy of Sciences, Branišovska 31, 37005 Česke Budějovice, Czech Republic.
authors.forename: Carlo Lutz
authors.initials: CL
authors.lastname: Seifert
authors.affiliation: Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, 1030 Vienna, Austria.
authors.forename: Lisamarie
authors.initials: L
authors.lastname: Lehner
authors.affiliation: Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, 1030 Vienna, Austria.
authors.forename: Christine
authors.initials: C
authors.lastname: Truxa
authors.affiliation: Department of Microbiology and Ecosystem Science, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Wanek
authors.affiliation: Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, 1030 Vienna, Austria.
authors.forename: Konrad
authors.initials: K
authors.lastname: Fiedler
keywords: Larval diet; Trophic position; δ13C; δ15N