How Queen Ants Live 500% more, Solved! and Is Oridonin better than Rapamycin?

Insulin signaling in the long-lived reproductive caste of ants

Long live the queen

A trade-off between reproduction and lifespan occurs across most living organisms. An exception is insects such as ants, in which reproductive activity is limited to one or a few “queens” that live much longer than nonreproductive “ workers. ” Studying a pseudo-queen state of the ant Harpegnathos saltator, Yan et al. found that the insulin and insulin-like growth factor signaling pathway was activated to promote reproduction, which also shortened life span. The authors propose that one branch of this pathway, mediated by the protein kinase Akt, is suppressed in the fat body and some ovarian tissues. Increased production of a protein that binds insulin-like molecules in the hemolymph might account for the difference that allowed the longer life span of the pseudo-queen. —LBR

Abstract

In most organisms, reproduction is correlated with shorter life span. However, the reproductive queen in eusocial insects exhibits a much longer life span than that of workers. In Harpegnathos ants, when the queen dies, workers can undergo an adult caste switch to reproductive pseudo-queens (gamergates), exhibiting a five-times prolonged life span. To explore the relation between reproduction and longevity, we compared gene expression during caste switching. Insulin expression is increased in the gamergate brain that correlates with increased lipid synthesis and production of vitellogenin in the fat body, both transported to the egg. This results from activation of the mitogen-activated protein kinase (MAPK) branch of the insulin signaling pathway. By contrast, the production in the gamergate developing ovary of anti-insulin Imp-L2 leads to decreased signaling of the AKT/forkhead box O (FOXO) branch in the fat body, which is consistent with their extended longevity.