Biodiversity on Earth ultimately depends on the origin of species by natural selection. Important driving forces of diversification are the evolutionary processes between parasites and their hosts.The obligate ectoparasitic Laboulbeniales fungi are associated with arthropods. Only some ant species are known hosts, and of only five species of these fungi. Of these five species, only Rickia wasmannii and Laboulbenia camponoti were known from Europe, until recent records of the exotic L. formicarum. These fungi are understudied in Europe and the few references about them are mostly records from new regions. Publications about the physiological and behavioural effect of these fungi on their ant hosts are not available but I hypothesise their strong evolutionary effect on the ants and vice versa. Based on the relatively easy laboratory culturing of ant colonies and to the large proportion of infected individuals within infected ant nests, ants are excellent model organisms to study the interaction of Laboulbeniales fungi with their hosts. Such general principles can potentially help also understand the adaptation mechanisms of other parasite populations to their hosts.My aim is to provide hitherto missing basic knowledge about the ant-Laboulbeniales system, and to foster deeper study of this interaction. My research will include distribution mapping, investigation of the transmission between ant colonies and testing the physiological and behavioural effect of these fungi on ant colonies. The results can be relevant for conservational questions (e.g. the rarity of R. wasmannii and L. camponoti, if they need any protection; or the effect of the exotic L. formicarum on the native ant species).This project will enable me to introduce new methods (e.g. GC-MS) and the research atmosphere acquired in Copenhagen (during a Marie Curie IEF), to learn new methods (e.g. SEM), and to collaborate with researchers across Europe, which will benefit my research career.