leptospermone and sulcotrione

The emergence of pesticides of natural origin appears as an environmental-friendly alternative to synthetic pesticides for managing weeds. To verify this assumption, leptospermone, a natural β-triketone herbicide, and sulcotrione, a synthetic one, were applied to soil microcosms at 0× (control), 1× or 10× recommended field dose. The fate of these two herbicides (i.e. dissipation and formation of transformation products) was monitored to assess the scenario of exposure of soil microorganisms to natural and synthetic herbicides. Ecotoxicological impact of both herbicides was explored by monitoring soil bacterial diversity and activity using next-generation sequencing of 16S rRNA gene amplicons and soil metabolomics. Both leptospermone and sulcotrione fully dissipated over the incubation period. During their dissipation, transformation products of natural and synthetic β-triketone were detected. Hydroxy-leptospermone was almost completely dissipated by the end of the experiment, while CMBA, the major metabolite of sulcotrione, remained in soil microcosms. After 8 days of exposure, the diversity and structure of the soil bacterial community treated with leptospermone was significantly modified, while less significant changes were observed for sulcotrione. For both herbicides, the diversity of the soil bacterial community was still not completely recovered by the end of the experiment (45 days). The combined use of next-generation sequencing and metabolomic approaches allowed us to assess the ecotoxicological impact of natural and synthetic pesticides on non-target soil microorganisms and to detect potential biomarkers of soil exposure to β-triketones.

Topics: Bacteria; Cyclohexanones; Environmental Monitoring; Herbicides; Mesylates; Metabolome; Phloroglucinol; RNA, Bacterial; RNA, Ribosomal, 16S; Soil Microbiology; Soil Pollutants

This study presents a novel approach for assessing the risk of agrochemicals in soil microcosms through the use of non-targeted metabolomics. The metabolome of treated soils was extracted and tested through LCMS profiling in order to generate an "Environmental Metabolic Footprint" (EMF). A dynamic characterization of pollution biomarkers was obtained through a multivariate statistical analysis of EMF data, where our results show the possible evolution towards a state of resilience. The EMF methodology was applied to two β-triketone herbicides in soil microcosms: one natural, leptospermone, and one synthetic, sulcotrione. In spite of a four-fold higher application dose, leptospermone exhibited a lower resilience time than did sulcotrione (ca. 30 days vs ca. 45 days respectively).

Topics: Cyclohexanones; Environmental Monitoring; Herbicides; Mesylates; Oils, Volatile; Phloroglucinol; Soil Microbiology; Soil Pollutants