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Workers of the Indian jumping ant carefully groom and inspect larvae to determine whether they are developing as queens or workers. Credit: Clint Penick

A queen’s path to the top of the hive is based on a bit of destiny – special pheromones – but also a bit of luck in timing, according to a new study in the journal Animal Behaviour.

The Indian jumping ants larvae marked with a so-called “princess pheromone” are the ones that have the capacity to develop into queens and start new colonies, according to the North Carolina State University team of researchers.

But if the larvae give off the scent at the wrong time for development, worker ants actually chew on it, stressing it so that it instead reverts into just another worker, according to the paper.

“Signals like the princess pheromone are essential to social insects,” said Clint Penick, lead author, and a postdoctoral researcher. “Ants have to have a way to ensure that there are enough workers in the colony, otherwise all larvae could develop as queens and the insect ‘society’ would break down.”

Harpegnathos saltator workers somehow identified the larvae with queen potential – despite them looking identical, the biologists noted.

A detailed investigation of the wax layer on the larvae’s cuticle and compared them to common workers’ wax layers.

The chemical composition was completely different – especially the presence of the princess pheromone.

“Gas chromatography revealed significant difference in cuticular hydrocarbon profiles of queen and worker larvae that could be induced by treatment with a juvenile hormone analogue,” they write.

The scientists also tested their findings by treating worker larvae with the triggering hormone, to also produce the “princess” stuff. Other workers then treated the workers – even if they were males – as queens, they report.

The pheromone-hierarchy findings could also carry over into other colony-based insects, they hypothesize.

“Given that H. saltator is from one of the older lineages of any, this mechanism is likely to be fairly common in social insects – but more work needs to be done to determine whether princess pheromones are present in other species,” they conclude.

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