@article{BoetzlKonleKrauss2019,
  author    = {Boetzl, Fabian A. and Konle, Antonia and Krauss, Jochen},
  title     = {Aphid cards - useful model for assessing predation rates or bias prone nonsense?},
  series = {Journal of Applied Entomology},
  volume    = {144},
  journal   = {Journal of Applied Entomology},
  number    = {1-2},
  doi       = {10.1111/jen.12692},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-204798},
  pages     = {74-80},
  year      = {2019},
  abstract  = {Predation on pest organisms is an essential ecosystem function supporting yields in modern agriculture. However, assessing predation rates is intricate, and they can rarely be linked directly to predator densities or functions. We tested whether sentinel prey aphid cards are useful tools to assess predation rates in the field. Therefore, we looked at aphid cards of different sizes on the ground level as well as within the vegetation. Additionally, by trapping ground-dwelling predators, we examined whether obtained predation rates could be linked to predator densities and traits. Predation rates recorded with aphid cards were independent of aphid card size. However, predation rates on the ground level were three times higher than within the vegetation. We found both predatory carabid activity densities as well as community weighted mean body size to be good predictors for predation rates. Predation rates obtained from aphid cards are stable over card type and related to predator assemblages. Aphid cards, therefore, are a useful, efficient method for rapidly assessing the ecosystem function predation. Their use might especially be recommended for assessments on the ground level and when time and resource limitations rule out more elaborate sentinel prey methods using exclosures with living prey animals.},
  language  = {en}
}
@article{KernerKraussMaihoffetal.2023,
  author    = {Kerner, Janika M. and Krauss, Jochen and Maihoff, Fabienne and Bofinger, Lukas and Classen, Alice},
  title     = {Alpine butterflies want to fly high: Species and communities shift upwards faster than their host plants},
  series = {Ecology},
  volume    = {104},
  journal   = {Ecology},
  number    = {1},
  doi       = {10.1002/ecy.3848},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-312015},
  year      = {2023},
  abstract  = {Despite sometimes strong codependencies of insect herbivores and plants, the responses of individual taxa to accelerating climate change are typically studied in isolation. For this reason, biotic interactions that potentially limit species in tracking their preferred climatic niches are ignored. Here, we chose butterflies as a prominent representative of herbivorous insects to investigate the impacts of temperature changes and their larval host plant distributions along a 1.4-km elevational gradient in the German Alps. Following a sampling protocol of 2009, we revisited 33 grassland plots in 2019 over an entire growing season. We quantified changes in butterfly abundance and richness by repeated transect walks on each plot and disentangled the direct and indirect effects of locally assessed temperature, site management, and larval and adult food resource availability on these patterns. Additionally, we determined elevational range shifts of butterflies and host plants at both the community and species level. Comparing the two sampled years (2009 and 2019), we found a severe decline in butterfly abundance and a clear upward shift of butterflies along the elevational gradient. We detected shifts in the peak of species richness, community composition, and at the species level, whereby mountainous species shifted particularly strongly. In contrast, host plants showed barely any change, neither in connection with species richness nor individual species shifts. Further, temperature and host plant richness were the main drivers of butterfly richness, with change in temperature best explaining the change in richness over time. We concluded that host plants were not yet hindering butterfly species and communities from shifting upwards. However, the mismatch between butterfly and host plant shifts might become a problem for this very close plant-herbivore relationship, especially toward higher elevations, if butterflies fail to adapt to new host plants. Further, our results support the value of conserving traditional extensive pasture use as a promoter of host plant and, hence, butterfly richness.},
  language  = {en}
}
@article{VikukFuchsKrischkeetal.2020,
  author    = {Vikuk, Veronika and Fuchs, Benjamin and Krischke, Markus and Mueller, Martin J. and Rueb, Selina and Krauss, Jochen},
  title     = {Alkaloid Concentrations of Lolium perenne Infected with Epichlo{\"e} festucae var. lolii with Different Detection Methods—A Re-Evaluation of Intoxication Risk in Germany?},
  series = {Journal of Fungi},
  volume    = {6},
  journal   = {Journal of Fungi},
  number    = {3},
  issn      = {2309-608X},
  doi       = {10.3390/jof6030177},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-213171},
  year      = {2020},
  abstract  = {Mycotoxins in agriculturally used plants can cause intoxication in animals and can lead to severe financial losses for farmers. The endophytic fungus Epichlo{\"e} festucae var. lolii living symbiotically within the cool season grass species Lolium perenne can produce vertebrate and invertebrate toxic alkaloids. Hence, an exact quantitation of alkaloid concentrations is essential to determine intoxication risk for animals. Many studies use different methods to detect alkaloid concentrations, which complicates the comparability. In this study, we showed that alkaloid concentrations of individual plants exceeded toxicity thresholds on real world grasslands in Germany, but not on the population level. Alkaloid concentrations on five German grasslands with high alkaloid levels peaked in summer but were also below toxicity thresholds on population level. Furthermore, we showed that alkaloid concentrations follow the same seasonal trend, regardless of whether plant fresh or dry weight was used, in the field and in a common garden study. However, alkaloid concentrations were around three times higher when detected with dry weight. Finally, we showed that alkaloid concentrations can additionally be biased to different alkaloid detection methods. We highlight that toxicity risks should be analyzed using plant dry weight, but concentration trends of fresh weight are reliable.},
  language  = {en}
}
@article{BeerJoschinskiSastreetal.2017,
  author    = {Beer, Katharina and Joschinski, Jens and Sastre, Alazne Arrazola and Krauss, Jochen and Helfrich-F{\"o}rster, Charlotte},
  title     = {A damping circadian clock drives weak oscillations in metabolism and locomotor activity of aphids (Acyrthosiphon pisum)},
  series = {Scientific Reports},
  volume    = {7},
  journal   = {Scientific Reports},
  number    = {14906},
  doi       = {10.1038/s41598-017-15014-3},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-170020},
  year      = {2017},
  abstract  = {Timing seasonal events, like reproduction or diapause, is crucial for the survival of many species. Global change causes phenologies worldwide to shift, which requires a mechanistic explanation of seasonal time measurement. Day length (photoperiod) is a reliable indicator of winter arrival, but it remains unclear how exactly species measure day length. A reference for time of day could be provided by a circadian clock, by an hourglass clock, or, as some newer models suggest, by a damped circadian clock. However, damping of clock outputs has so far been rarely observed. To study putative clock outputs of Acyrthosiphon pisum aphids, we raised individual nymphs on coloured artificial diet, and measured rhythms in metabolic activity in light-dark illumination cycles of 16:08 hours (LD) and constant conditions (DD). In addition, we kept individuals in a novel monitoring setup and measured locomotor activity. We found that A. pisum is day-active in LD, potentially with a bimodal distribution. In constant darkness rhythmicity of locomotor behaviour persisted in some individuals, but patterns were mostly complex with several predominant periods. Metabolic activity, on the other hand, damped quickly. A damped circadian clock, potentially driven by multiple oscillator populations, is the most likely explanation of our results.},
  language  = {en}
}