@phdthesis{Heitmann2024, author = {Heitmann, Nadja}, title = {Ground-dwelling arthropods as mobile linkers for the phytopathogenic fungi Fusarium and Alternaria}, doi = {10.26127/BTUOpen-6917}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus4-69179}, school = {BTU Cottbus - Senftenberg}, year = {2024}, abstract = {Actively moving animals connect populations by transporting other organisms and their propagules, such as seeds or spores. These animals are also known as genetic mobile linkers and can alter the genetic structure of populations. So far, the mobile link concept is rarely considered in studying the spatio-temporal patterns of plant diseases, although many of the causal agents are dispersed by arthropods. This study identifies the potential of ground-dwelling arthropods, especially carabid beetles, as mobile linkers for Fusarium, Alternaria and other filamentous fungi between crop fields and kettle holes. These small water bodies are surrounded by permanent semi-natural vegetation and are essential habitats for many arthropod groups. Many Fusarium and Alternaria species are relevant crop pathogens but are also often found in the litter layer and on weeds. Both fungal genera are often associated with various arthropod species and some Fusarium species are spread by arthropods in different cropping systems. However, it is not known whether beneficial arthropods also spread Fusarium and Alternaria, although an interaction within the litter layer is highly likely. Furthermore, carabid beetles are highly mobile and frequently move between arable and semi-natural habitats. At first, I quantified the interaction of carabid beetles and fungi by using pitfall traps in wheat fields close to the kettle hole margins and screened the beetles with molecular and microbiological approaches for fungal propagules (Chapter 3). The results showed that, carabid beetles frequently interacted with Fusarium, Alternaria and always with filamentous fungi in general. Furthermore, smaller carabid species showed a lower fungal load than larger ones. Thereupon, I aimed to identify the limitations of this dispersal mechanism by comparing the Fusarium community composition in the litter of the kettle hole margin, the crop field soil and the body surface of ground-dwelling arthropods. (Chapter 4). I detected three distinct Fusarium communities with the highest Fusarium species richness on the arthropods, which consisted of Fusarium species from both habitats. Therefore, the results indicate a non-selective transport mechanism of Fusarium propagules that neither promotes nor hinders certain species. At last, we analyzed the spillover effects of carabid beetles from kettle holes into adjacent crop fields with directional pitfall traps (Chapter 5). The distance to the kettle hole and the beetles' ingoing or outgoing movement direction did not significantly affect the carabid community. In contrast, the activity density was 1.6 and species richness was 1.1 times higher in early summer than in late spring. The taxonomical and functional composition also differed between the seasons. These results indicate that carabid beetles and other ground -welling arthropods might be relevant mobile linkers for Fusarium, Alternaria and other fungi and that seasonality might affect this mechanism.}, subject = {Ground-dwelling arthropods; Mobile linker; Mycobiota; Spillover; Semi-natural habitats; Bodenbewohnende Arthropoden; Mobile linker; Pilzgemeinschaft; Ausbreitung; Naturnahe Habitate; Bodenarthropoda; Fusarium; Habitat; Soll ; Verbreitungs{\"o}kologie}, language = {en} }