Elderly crickets are set in their ways, study finds

The results suggest that older crickets may struggle to respond to changing environmental conditions and would therefore be at a disadvantage relative to younger individuals in the face of changes in climate, habitat or diet or in the event of a natural disaster.

In the study, carried out by the University of Exeter, wild field crickets (Gryllus campestris) were set personality tests to measure their shyness, their inclination for activity and exploration and their tendency to leave a refuge.

The researchers found that the crickets, which had an adult lifespan of about 25 days, all had different personalities but, unlike humans, they tended to become more active as they grew older.

David Fisher from the Centre for Ecology and Conservation at the University of Exeter’s Penryn Campus in Cornwall said: “Even animals that only live for a very short time show signs of ageing, just like humans. Our results show that behaviour in field crickets tends to become more ingrained as the individuals age.”

Project leader Professor Tom Tregenza said: “This has important implications for our understanding of the survival prospects of older animals as it suggests that they may be less able to respond to changes in their environment.”

The study was carried out in a Spanish meadow wired up with 140 video cameras to capture the lives of an entire population of wild insects.  Crickets were caught, tagged, tested and released back into their burrows. The entrances to the burrows were monitored to enable the same individuals to be re-captured. They then underwent further personality testing to determine how their responses changed with age.

The research received funding from Natural Environment Research Council, the Leverhulme Trust and the Royal Society.

‘Dynamics of among-individual behavioral variation over adult lifespan in a wild insect’ is published in the journal Behavioural Ecology.

For more information see http://www.wildcrickets.org/