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Naked mole-rat secrets laid bare at annual odour lecture

A double lecture on the way naked mole-rats and leaf cutting ants use smells to ‘talk’ was held at Queen Mary, University of London last week in front of Britain’s leading experts in the flavour and perfume industries.

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Naked Mole Rat © Chris Faulkes
Naked Mole Rat © Chris Faulkes

Presentations were made at the annual joint meeting of the British Society of Flavourists and the British Society of Perfumers by Dr Chris Faulkes of Queen Mary and Dr Adam Hart of the University of Gloucestershire on the way that aroma and chemicals influence behaviour in different species.

While leaf-cutting ants and mole-rats last shared a common ancestor over 700 million years ago, both have independently evolved a highly social system known as ‘eusociality’. In large colonies of both creatures, reproduction is monopolised by a single breeding queen, while non-workers help to rear her young.

Dr Faulkes and Dr Hart gave a fascinating insight into the differences and similarities in the way that both species use odourous chemical signals, or chemosignals, to communicate and maintain these complex societies.

Guests were invited to smell and identify a range of pheromones- the chemicals secreted by animals that influence the development and behaviour of others of the same species- as many are the same chemicals used in perfume, food and medicines. Tanks of naked mole-rats and ants were also on display at the event for a closer look at their behaviour.

Colonies of mole-rats commonly contain up to 100 individuals. Reproduction is monopolised by the queen and one or two males while the rest act as ‘workers’, maintaining the burrow, or ‘soldiers’ defending the colony against predators. While these small subterranean rodents can live for around 30 years in captivity, 98 per cent spend their lives infertile.

In some species of ants and honey bees, a queen will secrete pheromones to suppress ovarian development in inferior members of the colony, but queen mole-rats effectively switch off reproduction in other mole-rats through physical interaction. By ‘bullying’ and inducing stress in her subordinates, she can stop ovulation in other females and lower testosterone concentrations and sperm numbers in non-breeding males.

Dr Faulkes explains: “Contrary to popular belief, our research shows that, unlike social insects, queen mole-rats do not use primer pheromones to reproductively suppress other males and females of breeding age. Their sense of smell is important but they are also extremely tactile creatures who use vocalisations and touch to communicate. Dominant members will, for example, clamber over those who are lower in the social order in order to exert their authority.”

“However, mole-rats do use odours in many other ways. Colonies have a distinct group odour and will discriminate against those from other groups, based on this odour. They will also leave odour trails for their colony mates, to lead them to food sources. After discovering food, they return to the rest of the group, wave the food and make a distinct ‘chirping’ noise. Research has shown that the others will automatically go along the same path as the first mole-rat, usually ignoring closer food in order to find the original piece that was discovered.”

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