One problem, many solutions: Female reproduction is regulated by chemically diverse pheromones across insects

Abstract The reproductive division of labour in social insects is a fascinating phenomenon regulated by diverse chemical signals that vary substantially in structure. Is this diversity an example of one problem (reproductive regulation) and many potential solutions (diverse chemicals)? Or are there hidden shared elements in the pheromonal regulation of reproduction across insects? To address this question, I will first discuss the phenomenon of reproductive division of labour in social insects, particularly, the reproductive conflicts among females and the means by which these conflicts are resolved. I will then focus on the use of pheromones, a mode of communication that has broadly diversified among social insects that live in large complex societies. I will summarize the different approaches to define semiochemicals in the context of the reproductive division of labour and review the state of knowledge of compounds regulating insect reproduction, both solitary and social, demonstrating the structural diversity as well as the potential conservation of the mechanisms regulating signal production and perception. Lastly, I will discuss the different hypotheses underlying the evolution of pheromones regulating reproduction in insects. Our current understanding of reproductive signalling, while extensive within single species, is still limited by the paucity of comparative studies across the Insecta as a whole, and further investigations are sorely needed.