Enantioselectivity of new chiral triazole fungicide mefentrifluconazole: Bioactivity against phytopathogen, and acute toxicity and bioaccumulation in earthworm (Eisenia fetida)

Elaborating the environmental behavior of mefentrifluconazole, a novel triazole fungicide, in stereoselective level is of paramount importance for the application of the pesticide in agriculture. In this study, the enantioselective bioactivity, acute toxicity and stereoselective bioaccumulation of mefentrifluconazole in earthworm (Eisertia fetida) were investigated. Bioactivity tests against four pathogens revealed that R-( - )-mefentrifluconazole exhibited approximately 11-113 times higher bioactivity than its S-( + )-mefentrifluconazole. However, the LC50 of S-( + )-, rac- and R-( - )mefentrifluconazole to earthworm was measured to be 4.1, 11.4 and 7.3 mu g/cm(2), respectively, indicating active ingredient R-( - )-mefentrifluconazole is less toxic than its racemate and S-form. Accumulation of mefentrifluconazole in earthworms was non-enantioselective and negatively related to its adsorption onto soils. The concentration of mefentrilluconazole in in situ pore water (C-IPW) and CaCl2 extraction (C-CaCl2) was closely related to its accumulation in earthworms, suggesting that C-IPW and C-CaCl2 could be appropriate indicators for estimation of the bioavailability of mefentrilluconazole in soil. Conclusively, our study provides necessary information for the risk assessment of mefentrifluconazole in agriculture.