Building around the tiered risk assessment approach, the PhD students in WP4 have developed and standardized assays to determine the toxicity of pesticides on AOM and AMF strains in vitro (DL. 4.1. and 4.2.). These constitute ready to implement Tier I – Single Species Tests that will be going through further ISO standardization as a main outcome of ARISTO. These results are described in two articles submitted in Environ. Sci. Technol (AOM) and Ecological Indicators (AMF). A booklet with detailed protocols for the cultivation of the tested AOM and AMF strains (DL 4.3.) and a database with EC50 values for a range of pesticides on AOM and AMF is provided (DL 4.4.). In WP5, the toxicity of pesticides on natural soil microbial assemblages was determined in lab and field trials (Tier II and III). Mesocosm experiments determined pesticide effects in the frame of climate change pressure with results indicating that AOM were affected mostly by drought/rewetting but not by pesticides. In parallel, a series of pot experiments identified potential off-target effects of a range of pesticides on the soil and intraradical AMF community. Finally, two field experiments were undertaken in France and Germany to define the impact of three selected pesticides on AOM and AMF natural soil assemblages. All these efforts are summarized in DL 5.1. and DL5.2. In WP6, ARISTO looked at the effects of pesticides across trophic levels and on microbial networks. Soil microcosm studies manipulated with different fractions of the soil microbiota showed for the first time the contribution of indirect effects on the soil microbiota. These results were published in the J. Hazard. Mat. (
https://doi.org/10.1016/j.jhazmat.2024.134231(s’ouvre dans une nouvelle fenêtre)). Parallel soil microcosms showed that the main driver of the bacterial community composition was the diversity of protists, and, if this is affected by the pesticides, then cascading effects on the bacterial community should be expected (DL 6.3). In WP7, fellows addressed open issues in ERA like the potential toxicity of pesticide mixtures and biopesticides on soil microbiota. Lab tests showed that abiotic stressors (e.g. heat or high moisture) combined with applications of pesticide mixtures have a compounded effect on the soil microbiota. Parallel soil microcosms showed that the OECD 216 test failed to identify effects of biopesticides on AOM which were clearly highlighted by q-PCR. This work was published in Pest Manag. Sci. (
https://doi.org/10.1002/ps.7961(s’ouvre dans une nouvelle fenêtre)). Furthermore, the use of Species Sensitivity Distributions (SSDs) using amplicon sequencing data was explored to obtain threshold values for risk assessment (HC5). Finally, in WP8, an in silico workflow for predicting and prioritizing pesticide transformation products according to their potential toxicity to AOM was developed (Zhang, Fenner, Bioinformatics, 39(7), 2023). Secondly, a model for predicting the toxicity of pesticides and their TPs on AOB was developed and validated with data from WP4. Finally, a graph neural network (GNN) model that had been pre-trained with lipophilicity data (logP) identified structural alerts linked to logP and toxicity towards nitrification (manuscript submitted to Env. Sci. Technol.).
