Biological control of soil-borne phytopathogenic fungi and their mycotoxins by soil fauna A review
Yield loss through harmful fungi is a serious problem in crop production worldwide. Cereal residues like straw are frequently infected by Fusarium fungi, which produce mycotoxins like deoxynivalenol (DON). Mycotoxins lead to quality losses in cereal-based food and feed which endangers human and animal health. Especially under conservation tillage, when mulching techniques are applied to protect soil from erosion, run-off etc., residues should be efficiently degraded to protect the currently cultivated crop from fungal infection and mycotoxin contamination. The objective of this review is to give an overview on which role decomposing soil fauna plays in the fate of Fusarium fungi and there main mycotoxin DON in the soil system. Generally, soil fauna benefits from conservation tillage compared to conventional tillage. Results from experiments in the laboratory and field revealed that earthworms as primary and secondary decomposers as well as fungivorous collembolans and soil nematodes contribute to the ecosystem services of pathogen depression and toxin degradation with respect to Fusarium and DON. Fusarium seems to be an attractive food source. Furthermore, the mycotoxin DON does not cause any harm to the soil fauna tested. Key factors for the control of Fusarium development by antagonistic soil fauna are: (1) interaction with soil microorganisms; (2) interaction of soil fauna species; (3) soil texture; (4) residue exposure. Ecosystem services of antagonistic soil fauna are vital to crop production and the functioning of agroecosystems. They will be discussed in a broader context of soil health and conservation tillage.