An Evo-Devo perspective on reproductive division of labour in wasps

The evolution of sociality in insects is an example of a so-called “major transition in evolution”, whereby previously solitary breeding insects went on to live in social groups. The question of what ancestral reproductive ground plans (RGPs) from solitary breeding insects have been co-opted in the evolution of their social behaviour is a topic of active study. Earlier, we have shown that conserved queen signals help to regulate the reproductive division of labour of insect societies and found that queen fertility and queen signal production can be under shared juvenile hormone (JH) control. In line with the RGP hypothesis, this shows that queen signals likely evolved from fertility cues produced as a byproduct of the ovarian cycle and associated hormone cycles of presocial insects. Likewise, patterns of division of labour among the workers, such as the nurse-forager transition, have sometimes been shown to be under JH control and were suggested to correspond to the multiple roles that JH may have played in regulating the behaviour of presocial ancestors. This “splitfunction hypothesis”, however, is as yet controversial, as it is also possible that this secondary function of JH was a later evolutionary innovation specific to social insects (“the novel function hypothesis”). Using a comparative analysis of Belgian and Neotropical wasps of different degree of sociality, the present project will test these two competing hypotheses on the origin of social behaviour in insects.