As part of an international study, we tested how well the Streambugs model can predict the impact of pesticides on aquatic ecosystems. We first further developed an existing model designed by the Swiss Federal Institute of Aquatic Science and Technology (Eawag). We tested this model using experimental data of mesocosm studies and compared the model output with other models. We were able to show which trends observed in the mesocosm studies were correctly represented by the model and where there is a need for further development. Our work contributes to the efficient use of models in environmental risk assessment.