Family before work: Task reversion in workers of the red imported fire ant, Solenopsis invicta in the presence of brood

Among social insects, task allocation within group members remains one of the paramount pillars of social functionality. Division of labor in many eusocial insects is maintained by behavioral flexibility in workers that allow the colony to respond efficiently to its needs. Workers, typically over time as they age, shift from intranidal nurses, to extranidal foragers. If the needs of the colony change, either from the needs of the adults or the brood therein, workers behaviorally shift to compensate for the need of a particular task. These cues that either accelerate workers towards a behavior associated with older workers or regressing back into the nest is not clearly understood in social insects outside of honey bees. In this study, we evaluated how brood and the different brood types can affect worker task reversion and acceleration in the red imported fire ant Solenopsis invicta. Through observation of worker behaviors performed over multiple time-points per day, we revealed that worker task reversion and acceleration does occur. Furthermore, we determined that the “type” of brood is important to influence the rate at which this occurred, with larvae having the strongest effect. Finally, the workers that had their behavior affected by the presence of brood retained their behavioral phenotypes for the remainder of the experiment, rather than shifting back to their original behavior intermittently. This study shows how the needs of brood within a social insect colony can influence the behavior workers perform, reversing the age polyethism that is common among social insect systems