Microbial pesticides: challenges and future perspectives for non-target organism testing

Biopesticides have received increasing global attention as environmentally friendly alternatives, allowing for more sustainable pest and disease control. In order to be registered or authorized for use, safety studies need to be submitted for regulatory risk assessments. However, it has been frequently reported that, in particular, microbial pesticides have a number of challenges when it comes to non-target organism testing. For instance, study results from such tests are often difficult to interpret or they lack consistency and accuracy. Reasons for this can be found firstly in the heterogeneity and resulting complexity of microbe-based pesticides comprising different taxonomic groups (e.g., bacteria, fungi, and viruses), and secondly in the lack of appropriate guidance for testing these different microbial agents considering their unique biological properties. The present review gives an overview of the available test guidelines by reflecting the current regulatory background in the area of environmental risk assessment of microbial pesticides and describes general and specific issues associated with safety studies on terrestrial vertebrates, aquatic organisms, bees, non-target arthropods other than bees, meso- and macro-organisms in soil, and non-target terrestrial plants. Proposals for improvement of existing test guidelines or guidance documents are provided and further discussed.