A behavioural syndrome in the field cricket Gryllus integer: intrasexual aggression is correlated with activity in a novel environment

Behavioural syndromes, or suites of correlated behaviours across different contexts and situations, have recently drawn attention from evolutionary biologists. In the field cricket Gryllus integer , males are aggressive with one another and fight vigorously over females and territories. We examined whether aggressiveness with other males was correlated with activity in a potentially dangerous context (a novel environment) in laboratory-raised virgin males. Aggressiveness was measured as fighting ability against a weight-matched opponent. First, we measured each cricket's latency to become active in a novel environment and latency to emerge from a refuge within a novel environment. Next, we determined which of two weight-matched males was more aggressive, by pitting the males together in an agonistic contest and counting the number of fights won by each male. More aggressive males, who won more fights, had shorter latencies to become active when placed in a novel environment and shorter latencies to emerge from a safe refuge. These results suggest that a behavioural syndrome exists in G. integer , in which more aggressive males are also more active in general, and possibly less cautious towards predation risk.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 91 , 475–482.