Dietary preferences of Heteromurus nitidus (Collembola) among wheat fungal communities: Implications for bioregulation of two widespread pathogens

Soil invertebrates play a key role in agrosystems as providers of several ecosystem services. In particular, they regulate fungal communities in soils and could contribute to mitigate the impact of phytopathogenic fungi overwintering in crop residues. In this study, we investigated the food preferences of Heteromurus nitidus (Col-lembola) between phytopathogenic and non-pathogenic (or beneficial) fungi present in crop soils and grown in vitro. First, two fungi responsible for the most important diseases of wheat worldwide Zymoseptoria tritici and Fusarium graminearum, and eleven fungi previously served on wheat plants were offered in pathogenic/non-pathogenic pairs to springtails. We showed that Z. tritici was preferred over seven out of the eleven non-pathogenic fungi offered while F. graminearum was only preferred over four of them. Second, we assessed the impact of long-term consumption of these two phytopathogenic fungi by springtails on their population devel-opment and assessed how the development of the fungi was affected by the springtails that fed on them. During this long-term experiment, springtails were more abundant in populations fed with phytopathogenic fungus than in control populations after ten weeks. At the end of the experiment, mycelium of both fungi was reduced by springtail activity. These in vitro results suggest a potential of H. nitidus to act as a biological control agent as populations grew when fed on either fungus while reducing fungal development. This point should be confirmed by testing the fungus grown on host plant tissues and with experiments involving interactions with soil and its communities. Z. tritici appears to be a better candidate for such experiments as it was preferred in choice experiments.