Discussionĭue to the obvious trait filtering and resulting altered assemblages, we suggest not to use pitfall traps with extended plastic rim plates. Pitfall traps with extended plastic rim plates did not only perform poorly but also resulted in distinct carabid assemblages with less individuals of small species and a larger variation. Pitfall traps with guidance barriers were up to five times more effective than simple pitfall traps and trap samples resulted in more similar assemblage approximations. About 20 traps were active for 10 weeks and emptied biweekly resulting in 100 trap samples. We tested four pitfall trap types which have been used in previous studies for their effectiveness: a simple type, a faster exchangeable type with an extended plastic rim plate and two types with guidance barriers (V- and X-shaped).

The effects of different pitfall trap designs on the trapping outcome are poorly investigated however they might affect conclusions drawn from pitfall trap data greatly. Pitfall traps are commonly used to assess ground dwelling arthropod communities. It’s a matter of design-how pitfall trap design affects trap samples and possible predictions. Cite this article Boetzl FA, Ries E, Schneider G, Krauss J. For attribution, the original author(s), title, publication source (PeerJ) and either DOI or URL of the article must be cited. Licence This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. 2 Regierungspräsidium Karlsruhe, Referat 56-Naturschutz und Landschaftspflege, Karlsruhe, Germany DOI 10.7717/peerj.5078 Published Accepted Received Academic Editor Joseph Gillespie Subject Areas Agricultural Science, Conservation Biology, Ecology, Entomology Keywords Biodiversity estimation, Spiders, Carabid beetles, Ground dwelling predators, Staphylinid beetles, Sampling method, Inventory, Species richness Copyright © 2018 Boetzl et al.