Dung Coleoptera communities in a modified wetland landscape in Argentina

Wetlands are being increasingly affected by anthropogenic activities worldwide. In the Lower Delta of the Paraná River, one of the most important wetlands in Argentina, a high stocking rate livestock system with intensive hydrological management has been implemented in recent decades. This implied the construction of structures that modify surface and subsurface watercourses, altering the function and structure of this wetland landscape. In addition, the use of veterinary antiparasitics during cattle raising represents a risk to the environment and the biodiversity. This work aims to compare dung Coleoptera communities in fields with different livestock management in the Lower Delta of the Paraná River. Fields were differentiated according to hydrological management (low, n=3; high, n=3) and ivermectin application within 60 days prior to sampling (yes, n=3; no, n=3). Sampling was performed during summer 2021 and autumn 2022. In the laboratory, all Coleoptera were separated and identified to the lowest possible taxonomic level, differentiating morphospecies. A total of 548 adult individuals belonging to five families and 24 morphospecies were identified. Total abundance of Coleoptera was higher in fields with low hydrological management. Species richness was slightly higher in fields with low hydrological management. This greater equity suggests a more stable morphospecies complex and an assemblage that is more resilient to disturbances. Conversely, ivermectin application did not modify the assemblage composition. The results reflect the composition of the dung community associated with livestock production under modified conditions in a wetland landscape, and the need to implement environmentally sustainable production strategies.