Long live queens! But why?
By Dr Nathan Woodling
Ovaries might change growth cues
to extend lifespan!
A queen takes the throne.
By Dr Andrew Holmes
Insulin surges, eggs grow.
A switch extends life.
Reproduction is linked to reduced lifespan in many animals, yet ant queens have a far greater longevity compared to workers in their colony – black garden ant queens can live up to 30 times longer than the 1-year lifespan of their workers. Ant queens have the same genome as their workers, and in some species of ant they aren’t reared differently but switch caste following the death of the current queen.
The Indian jumping ant (Harpegnathos saltator) exhibits this switching behaviour. When a queen dies, workers duel each other, with the winners transitioning into pseudo-queens known as gamergates. These gamergates begin laying fertile eggs and their lifespan is substantially increased – from 7 months to 4 years. Gamergates can even transition back into the worker caste if replaced by another queen, their lifespan reverting back to 7 months.
How is ant lifespan so mutable?
New research by Yan et al. (2022) points to an insulin-suppressing protein as a possible answer.
The researchers compared gene expression during caste switching and found that ants that switch from worker to gamergate produce more insulin. The increased insulin results in a change in the balance of activity between the two main insulin signalling pathways, MAPK (which controls metabolism and egg formation) and AKT (which controls ageing).
On transitioning to a gamergate, the MAPK insulin signalling pathway’s activity increases, inducing ovary development and the production of eggs. But this also results in the production of an insulin-suppressing protein (Imp-L2) which blocks the AKT insulin signalling pathway, increasing longevity.
IMP-L2 essentially acts as a switch between a worker being short-lived and sterile compared to a queen being long-lived and fertile.
Original research:
http://dx.doi.org/10.1126/science.abm8767
A note about the sciku:
Nathan and Andrew independently wrote their sciku about this research and discovered the coincidence when Nathen posted his poem on Twitter. The two different approaches to writing about the same subject demonstrate why sciku are such a consistently interesting medium for exploring and sharing research.
Author bios:
Dr Nathan Woodling is a lecturer in molecular biosciences at the University of Glasgow. You can follow him on Twitter here: @NathanWoodling.
Dr Andrew Holmes is a former researcher in animal welfare and the founder and editor of The Sciku Project. You can follow him on Twitter here: @AndrewMHolmes.