The route of Flupyradifurone (BYI 02960) degradation in soil was studied using different radiolabel positions, [pyrindinyl-methyl-14C = PYM], [pyridine-2,6-14C = PYR], [furanone-4-14C = FUR] and [ethyl- 1-14C = ETH] BYI 02960. The data gathered in the aerobic soil metabolism studies demonstrated that BYI 02960 is degraded in soil. When using the PYM label in four different European aerobic soils no major metabolites were detected. All formed metabolites were regarded as transient, which was confirmed by the high mineralization rate to 14CO2, i.e. up to 58.6% of AR from [PYM-14C] BYI 02960. The portions of not extractable residues (NER) were comparatively low throughout the study (max 16.8% of AR) in case of [PYM-14C] BYI 02960. As minor transformation products BYI 02960-chloro (max. 1.8%) and BYI 02960-des-difluoroethyl (max. 0.4%) were identified (for structures see Figure B.8.1.3-01). In studies with the FUR label (four European and two US soils) similar results were obtained with regard to the formation of NER (maximum 34.1% of AR) and extensive mineralization to 14CO2 (up to 38.9% of AR). With the exception of 14CO2 no major metabolites were formed in any of the soils. Degradation, amount of NER as well as of 14CO2 formed in sterilised soil was significantly less than in non-sterile soils, indicating a biological component to the degradation/mineralization and formation of non-extractable residues from BYI 02960. Additionally, soil fractionation showed that even with extraction using strong base, BYI 02960 related residues remain bound to the solid (humin) fraction indicating very strong and irreversible binding to soil. When using [ETH-14C] BYI 02960 in three aerobic soils one major metabolite, identified as difluoroacetic acid (max. 33.9% of AR), and one very minor metabolite was detected and quantified. Again, significant amounts of 14CO2 (up to 42.3% AR) were measured, indicating that mineralization of the test item and/or its metabolites occurred. The maximum amount of NER was relatively low at 17.9% of AR. The biotransformation of [PYR-14C] BYI 02960 was studied in one aerobic EU and two US soils. The mineralization to 14CO2 was significant (max. 57.4, 20.2 and 36.1% of AR) with the formation of minor metabolites in two soils. However, in one US soil, one major metabolite, which was identified as 6-chloronicotinic acid, was formed at maximum of 17.1%. NER formation was in the range of max. 11.3 to 25.5% of AR in the three soils. Considering the results from laboratory soil metabolism studies the major routes of degradation of BYI 02960, under aerobic conditions, are: cleavage of the difluoroethyl group producing difluoroacetic acid (DFA), cleavage of the molecule at the pyridinylmethylene bridge with subsequent oxidation to 6- CNA, mineralization to CO2 and formation of non-extractable residues. Degradation under anaerobic conditions and due to photolysis on the soil are not relevant routes for BYI 02960.