Personality is consistent according to cockroaches

One major question in personality research is when traits develop and stabilise. Now a team of scientists from Liverpool John Moores University and the University of Manchester have released the findings of a personality study, published in PLOS ONE, using cockroaches and revealing that personality stays consistent even through age and new development stages. They found that a bold juvenile will likely develop into a bold adult.

Individual Pacific beetle cockroaches Diploptera punctata were exposed to certain behavioural tests, for example placing them in a novel environment and measuring their tendency to leave a safe shelter and explore, as both young nymphs and adults.

Co-author Dr Claudia Mettke-Hofmann from Liverpool John Moores University’s School of Natural Sciences and Psychology, explains:

“We wanted to question if adults displayed the same behavioural response and therefore personality as they did as youngsters. As insects often go through multiple developmental stages before they reach adulthood, they are the perfect group in which we can explore when personality becomes apparent.

“The exciting finding is that although adults are less bold than nymphs, the relative boldness persists across stages for an individual. A cockroach being characterised as bold in the nymph stage will also be bold as adult.

“As this remains the same across distinct developmental stages, there must be clear advantages to this. High levels of boldness, for example, may be useful in terms of within-species competition for mates or food, but this may have negative consequences in other situations such as encounters with predators.”

It is one of relatively few studies to consider how insects can vary in how they respond to their environment, based on their personality.

Dr Christina R Stanley, Lecturer in Animal Behaviour & Welfare, who is the lead author, now based at the University of Chester, carried out the PhD study while at the University of Manchester. She said:                                                                                                                                    

“The idea that even insects can show variation in personality may sound a little far-fetched, but numerous studies across a range of species have now demonstrated that individuals can differ consistently in their responses to certain situations. From firebugs to honeybees, traits such as boldness and novelty-seeking have been shown to exist and have been quantified by scientists in controlled tests. Personality is therefore an important tool in the game of life and has implications across a range of contexts, from medical research to animal welfare.”

Professor Richard F Preziosi, co-author, the Manchester Metropolitan University said:

“The results are useful in terms of improving an understanding of when animal personalities become stable and over what kind of time-frame they may be beneficial. They also show that a certain degree of flexibility can be advantageous in the expression of personality traits such as boldness; these traits may differ in their strength over time. However, research such as this also highlights that even insects can differ consistently in their responses to their environment and that some traits persist across developmental stages.”

The research was published in Journal PLOS ONE

Personality in the Cockroach Diploptera punctata Evidence for Stability Across Developmental Stages Despite Age Effects on Boldness

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