@article{KrimmerMartinHolzschuhetal.2022,
  author    = {Krimmer, Elena and Martin, Emily A. and Holzschuh, Andrea and Krauss, Jochen and Steffan-Dewenter, Ingolf},
  title     = {Flower fields and pesticide use interactively shape pollen beetle infestation and parasitism in oilseed rape fields},
  series = {Journal of Applied Ecology},
  volume    = {59},
  journal   = {Journal of Applied Ecology},
  number    = {1},
  doi       = {10.1111/1365-2664.14051},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-258037},
  pages     = {263-273},
  year      = {2022},
  abstract  = {Pollen beetles (Brassicogethes spp.) are the main pests of oilseed rape (OSR, Brassica napus) in Europe and responsible for massive yield losses. Upcoming pesticide resistances highlight the need for other means of crop protection, such as natural pest control. Sown flower fields aim to counteract the decrease of insect biodiversity in agricultural landscapes by providing resources to ecosystem service providers. However, the optimal age and size of flower fields to increase natural pest control is still unclear. We conducted experiments on 31 OSR fields located along a gradient of landscape-scale semi-natural habitat (SNH). OSR fields were located adjacent to flower fields which differed in age, continuity and size, or adjacent to crop fields or calcareous grasslands. Pesticide-free areas were established to examine interactive effects of pesticide use and flower field characteristics. The abundance of pollen beetle adults and larvae, parasitism and superparasitism rates in OSR were recorded at increasing distances to the adjacent sites. Flower fields and calcareous grasslands increased pollen beetle parasitism when compared to OSR fields neighbouring crop fields. The threshold for effective natural pest control of 35\% could be reached in the pesticide-free areas of OSR fields adjacent to calcareous grasslands and flower fields maintained continuously for at least 6 years. In pesticide-sprayed areas, pollen beetle parasitism and superparasitism declined with increasing distance to the adjacent field. Furthermore, flower fields larger than 1.5 ha were able to improve pollen beetle parasitism more than smaller fields. Synthesis and applications. To promote natural pest control in oilseed rape (OSR), large flower fields should be maintained for several years, to create stable habitats for natural enemies. The continuous maintenance of flower fields should be preferred, as ploughing and resowing after 5-6 years decreased the positive effects of the flower fields on natural pest control in adjacent OSR fields. However, pesticide use can abrogate positive effects of flower fields on pollen beetle parasitism. This study highlights that sown flower fields have the potential to increase natural pest control in OSR, but this potential is depending on its age, continuity and size and can be hindered by pesticide use.},
  language  = {en}
}
@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}
}