Brain and antennal transcriptomes of host ants reveal potential links between behaviour and the functioning of socially parasitic colonies

Social ant parasites are characterised by exploiting the social behaviour of their hosts. Why exactly hosts direct their altruistic behaviour towards these parasites and their offspring remains largely unstudied. One hypothesis is that hosts do not perceive their social environment as altered and accept the parasitic colony as their own. We used the ant Leptothorax acervorum, host of the dulotic, obligate social parasite Harpagoxenus sublaevis to shed light on molecular mechanisms underlying behavioural exploitation by contrasting tissue-specific gene expression in young host ants. Therefore, host pupae were experimentally (re-)introduced into parasitic colonies, their natal, or another conspecific colony. After the emerged host workers were about 10 weeks old, we recorded their behaviour and then sampled them for sequencing of antennal and brain gene expression to analyse genes affected by the social environment the ants lived in as well as those genes that correlate with the behaviours performed the hour before sampling.