Molecular and social regulation of worker division oflabour in fire ants
Résumé
Reproductive and worker division of labour (DOL) is a hallmark of social insect societies.Despite a long-standing interest in worker DOL, the molecular mechanisms regulatingthis process have only been investigated in detail in honey bees, and little isknown about the regulatory mechanisms operating in other social insects. In the fireant Solenopsis invicta, one of the most studied ant species, workers are permanentlysterile and the tasks performed are modulated by the worker’s internal state (age andsize) and the outside environment (social environment), which potentially includes theeffect of the queen presence through chemical communication via pheromones. However,the molecular mechanisms underpinning these processes are unknown. Using awhole-genome microarray platform, we characterized the molecular basis for workerDOL and we explored how a drastic change in the social environment (i.e. the suddenloss of the queen) affects global gene expression patterns of worker ants. We identifiednumerous genes differentially expressed between foraging and nonforaging workersin queenright colonies. With a few exceptions, these genes appear to be distinct fromthose involved in DOL in bees and wasps. Interestingly, after the queen was removed,foraging workers were no longer distinct from nonforaging workers at the transcriptomiclevel. Furthermore, few expression differences were detected between queenrightand queenless workers when we did not consider the task performed. Thus, the socialcondition of the colony (queenless vs. queenright) appears to impact the molecularpathways underlying worker task performance, providing strong evidence for socialregulation of DOL in S. invicta.
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