One of the most dramatic examples of parasites controlling behaviour is the manipulation of ants infected by the fungus Ophiocordyceps unilateralis, causing them to bite into vegetation before dying.Most work so far has described the ant’s behaviour. I plan to study the process behind this behaviour from the fungal genome point of view. The environment experienced by the fungal parasite changes dramatically as it goes from infection to manipulation. Therefore, the transcriptome of this mind controlling fungus is expected to be highly heterogeneous. To test this hypothesis and elucidate the complex genetic mechanisms behind adaptive parasite manipulation of host behaviour I will use a single cell, whole transcriptome analysis protocol I pioneered and apply it to this emerging model. This will allow me to sample cells in different parts of the ant’s body during different phases of the lifecycle. I will combine this with LC/MS in fungal cells transferred between artificial ant environments to elucidate the fungal metabolites that are secreted in different parts within the host. Recently, it has been discovered that manipulated biting behaviour is synchronized at noon. This indicates that the fungal circadian clock might have a big influence on this parasitic behavioural control. Therefore, I will combine my findings with chronobiology to test the hypothesis if this heterogeneous activity is a function of circadian rhythm.An important additional objective of this proposal is advanced training facilitating my transition to independence.