PhD Student Texas A&M University College Station, Texas
The red imported fire ant Solenopsis invicta Buren provides an interesting system to examine factors underlying worker task allocation and transition as they are highly eusocial insect where workers are unable to reproduce whilst still expressing genes associated with reproduction such as vitellogenins (vg). In eusocial insects, levels of juvenile hormone (JH) can be associated with task performed in workers.
In this study, we examined the role of a JH analog on behaviors associated with task in S. invicta workers. Workers performing nursing behaviors were sampled from colonies and treated with JH analog S-Hydroprene over a 7-day period. Dosed nurses were observed to see 1) response to light as a proxy for foraging, and 2) where they would congregate within a micro colony. After observation, worker RNA was purified and expression of genes differentially expressed between nurses and foragers were measured. We saw no differences in worker response to light among treatments, but nurses treated with S-Hydroprene were significantly more attracted to protein and carbohydrate sources rather than brood within microcolonies compared to controls. Changes in expression in response to the JH-analog were measured for some but not all the tested genes.
These findings indicate that while the role of JH in S. invicta workers remains unclear, it can affect nurse worker behavior to become more like that of a forager. Further work is needed characterizing the molecular basis of worker task transition in fire ants, and advancements will provide possible alternative methods for regulation for this pest species.
