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Soil fauna effects on degradation of Fusarium graminearum mycotoxins in contaminated plant residues at different temperature regimes

Friederike Meyer-Wolfarth: Johann Heinrich von Thuenen-Instiute of Biodiversity

<div>Infection of cultivated plants with toxigenic fungal pathogens may lead to increased mycotoxin levels in crop products and residues. By leaching from host tissue of infected plants, mycotoxins can enter soil and water as potential environmental contaminants. In agroecosystems, fungivorous soil fauna can be antagonistic to pathogen infection and mycotoxin contamination and act as biological and chemical regulators. Therefore, a microcosm-study with earthworms (<em>Aporrectodea caliginosa</em>) and collembolans (<em>Proisotoma minuta</em>) was conducted in a climate chamber to assess their biocontrol-impact on the fungal plant pathogen <em>Fusarium graminearum</em> and the content of its mycotoxins deoxynivalenol (DON) and zearalenone (ZEN) in maize stubbles, soil, and leaching water. Soil fauna was exposed to artificially infected maize stubbles highly contaminated with DON (10,462 µg kg<sup>-1</sup>) and ZEN (2,780 µg kg<sup>-1</sup>) at 17°C or 25°C. After 6 weeks, maize, soil, and leaching water samples were analysed for mycotoxins via liquid chromatography coupled to high resolution mass spectrometry. First results indicate significant faunal effects of both introduced species on DON reduction in residual maize. At 25°C, DON was reduced most in mixed faunal treatment compared to the non-faunal control. A faunal effect on ZEN reduction was not observed. The introduced soil fauna contributes to the natural self-regulation in the soil system. However, their biocontrol potential is influenced by temperature.</div>

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