An insulin-suppressing protein may be responsible for the five-fold increase in longevity in queen ants compared to worker ants, noted a recent study.
Generally, species with a faster metabolism for reproduction are associated with a shorter life span. Ants are a notable exception to this generally accepted rule.
The queen ants, who are in charge of the colony’s reproduction, have a substantially longer lifespan than the worker ants despite having the same DNA, according to the study published in Science September 1, 2022.
For instance, a black garden queen ant can produce one million eggs and live for 30 years, unlike her sterile worker sisters, who only have one year’s lifespan.
Queen ants and worker ants are the two female groups in ant colonies. Queen ants lay eggs and worker ants stay in the nest and complete tasks like tending to the young.
Queen ants produce an anti-insulin protein that blocks a portion of the insulin chemical pathway in the body, responsible for ageing, noted the researchers from New York University.
Animals with more offspring often have shorter lifespans. This trade-off is assumed to be the result of the distribution of nutritional and metabolic resources among the offspring.
“Most manipulations of longevity in animals like mice or flies usually extend their lifespans by 10-20 per cent. Ants exhibit a remarkable 500 per cent increase in longevity, which makes studying them much more powerful,” said Claude Desplan, an author of the study.
Insulin, which aids in converting food into energy, is crucial to metabolism and ageing, according to some previous studies.
The laborious and energy-intensive process of laying eggs causes most animals to consume more and have higher insulin levels. But, this increased activity of the insulin pathway, which is necessary for reproduction, also shortens the life span.
The researchers observed Harpegnathos saltator ant, a native of India, whose queens often live for five years, but workers live for around seven months.
“Harpegnathos ants provide a unique opportunity to study how ageing and reproduction can be disconnected,” added Desplan.
A strange thing happens when a Harpegnathos queen dies in a colony. Female worker ants fight with their antennae to become the new queen. While still residing in a worker ant’s petite body, the winner transforms into a ‘pseudoqueen’ and alters their position in the ant colony.
Pseudoqueens extend their life span from seven months to four years and develop queen-like traits, such as the production of eggs. However, if another queen steps in to take their position, they revert to the status of a worker, stop laying eggs and reduce their lifetime to seven months.
“This interplay, which evolved in ants and perhaps in other insects, may contribute to the unusual longevity and many offspring in reproducing ants,” said Hua Yan, the study’s co-first author.
The researchers examined tissue samples from workers and pseudoqueens using bulk RNA-sequencing, concentrating on ant organs involved in metabolism and reproduction, such as the brain, fat body (an insect’s liver) and ovaries. The ants that changed from workers to pseudoqueens produced more insulin in their brains in order to create eggs, they noted.