Biological Control of Soil-borne Phytopathogenic Fungi and their Mycotoxins by Soil Fauna

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.