Comparison of dung and soil fauna from pastures treated with and without ivermectin as an example of the effects of a veterinary pharmaceutical

Soil organisms in manure or organisms that colonize dung pats can be impacted by the application of veterinary medical products, especially parasiticides, to livestock. For this reason, the authorization process for veterinary medicinal products in the European Union and other countries includes a requirement for “higher-tier” tests when adverse effects on dung organisms can be detected in single-species toxicity tests. However, no guidance documents for the performance of higher-tier tests are available, so far. Therefore, an international research project was undertaken to develop and validate a proposed test method under varying field conditions of climate, soil, and endemic coprophilous fauna. The test took place at Lethbridge (Canada), Montpellier (France), Zurich (Switzerland), and Wageningen (The Netherlands). The aim of the project was to determine if fecal residues of a parasitide with known insecticidal activity (ivermectin) showed similar effects on insects breeding in dung of treated animals, coprophilous organisms in the soil beneath the dung, and rates of dung degradation.