TY - CHAP A1 - Weiss, Fabio A1 - Linde, Andreas T1 - How precise are size-weight equations for estimating carabid biomass and how could they be improved? T2 - 22. Tagung der Deutschen Gesellschaft für allgemeine und angewandte Entomologie e.V. (DGaaE) 2023 in Bozen, Italien N2 - Insect biomass has been used as an ecological indicator in the past, but in recent years has become a key metric in the study of insect population trends, especially since first reports about the so-called insect decline (e.g. “Krefeld study” of 2017). However, measuring insect biomass can be methodologically challenging, and very labour intensive. For many datasets, weight measurements are not available and the original samples may have already been lost. Size-weight equations provide a straightforward method for estimating insect biomass when the insect’s body length is known. If insects have been determined to species level one can also use the average body length given in literature. Based on the correlation between the body length and the weight of an insect, there is a variety of size-weight equations for different groups of insects. They are widely used in insect research, but have rarely been tested with independent data. We evaluated two size-weight models for carabid beetles, by Szyszko (1983) and Booij et al. (1994), drawing on previously published independent data by comparing model predictions with actual measurements of biomass, using relative deviation graphs and observed versus predicted from regression. Moreover, we also tested if the inclusion of additional taxonomic parameters, in this case subfamily, can improve results. We found that both models produced systematically biased results: Szyszko´s model gave more accurate results for larger species, while the model of Booij et al. did so for smaller species. This bias is most likely caused by the different origin of the respective training data. This underlines the restricted applicability of such models. We demonstrate that additional taxonomic parameters have the potential to increase the accuracy of size-weight equations and represent a potential solution to the issue of restricted applicability. As actual biomass measurements for carabids are scarce, data availability is limited to only few subfamilies. Until data on more subfamilies become available, we recommend a combined use of both evaluated models: Szyszko’s model for carabids ≥ 11.8 mm, and the model of Booij et al. for carabids < 11.8 mm, respectively. KW - insect decline KW - insect biomass KW - insect monitoring KW - Carabidae Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:eb1-opus-3966 ER -