Molecular mechanisms of task allocation in workers of the red imported fire ant, Solenopsis invicta
The red imported fire ant Solenopsis invicta is an invasive pest in the USA, eastern Asia and Australia that causes billions worth of damage where it has been introduced. In the insect colony, workers perform tasks based on their age as well as the subcaste, where the younger workers as well as the members of the smaller subcastes of workers tend to remain in the nest and tend to the brood while the older ants as well as the members of the larger subcastes of workers leave the nest to perform activities such as foraging. In eusocial insects, juvenile hormone has been identified to be a catalyst for behavioral changes among the worker caste, but the involvement of this hormone in S. invicta task allocation has not been investigated. Here, we conducted RNAseq analysis to identify genes associated with worker division of labor by comparing the expression profiles of foragers and nurses from the medium subcaste. Additionally, we evaluated the changes in the transcriptome of nurses in response to the application of the juvenile hormone analog, S-hydroprene. We found 816 differentially expressed genes between foragers and nurses and 100 differentially expressed genes between nurses treated with acetone and nurses treated with S-hydroprene. Here, we focused on the differentially expressed genes between foragers and nurses that were associated with different molecular pathways such as energy metabolism, glycolysis, juvenile hormone synthesis and metabolism, and immunity. Our results showed that the juvenile hormone analog induced changes in worker gene expression, some of which were as expected if the juvenile hormone is involved in regulating the shift from nursing to foraging in S. invicta workers. This analysis and data from this experiment can provide a slew of potential target genes to be used for control of this invasive pest. Overall design: Performed transcriptomic analyses of fire ant worker samples taken from Illumina NovaSeq