Fight or flight response determined by nitric oxide release, in world of crickets

When a Mediterranean field cricket decides to fight or run way is determined by a chemical in the brain. When the fight reaches a certain point, the brain in one of the two rivals releases nitric oxide, which triggers a ‘flight’ response and the insect flees.

As soon as nitric oxide levels come back to normal, the cricket that opted to escape recovers its courage and is ready for the next fight. Until then, it will cower and behave in a submissive way towards the rival that stood its ground.

For animals, including humans, fighting is dangerous. We have to choose to flee as soon as we realize the potential harms are greater than the benefits. However, very little is known about the underlying mechanisms of the decision-making process for this.


When nitric oxide is released in the brain, the cricket runs away.

Thanks to this study, we now know that in the world of Mediterranean field crickets (Gryllus bimaculatus), the point at which they decide they have reached their limit is triggered by a chemical.


Paul Stevenson, from the Institute for Biology at Leipzig University, and Jan Rillich, from the Institute for Neurobiology at the Free University of Berlin, both in Germany, wrote about their findings in the academic journal Science Advances (citation below).

In the video below, you can see a confrontation between two rivals. As soon as the loser reaches its limit, it runs off.

When the two meet again the loser tries to keep out of the way of the victor. This submissive behavior is prompted by nitric oxide release, which lasts a number of hours before the ‘coward’ behavior is gone.

Fight duration and/or escalation determined by nitric oxide

Stevenson and Rillich found that the insects treated with nitric oxide did not fight for as long, or escalate violence, compared to the untreated insects.

However, those treated with nitric oxide suppressing drugs fought for longer and were more likely to escalate aggression.

Mr. Stevenson, a neurobiologist, said:

“If you block nitric oxide they recover quickly, and if you give them nitric oxide they don’t. It’s a very simple algorithm for controlling a very complicated social situation.”

In a 2011 study, Mr. Stevenson found that winning crickets became more aggressive and more successful fighters afterwards.

Video – Cricket fight or flight response