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Serotonin triggers desert locust swarms

Date: 07 June 2020 Tags: Disaster & Disaster Management


Researchers have discovered a new novel technique of preventing locusts swarm from causing damage to crops. This technique uses chemical inhibitors to trigger behavioural changes in the insects, leading to their reduced numbers.



During the last few days, there has been a lot of news about the latest locust swarming from the Rajasthan/Gujarat desert region, all the way into Madhya Pradesh and Chhattisgarh, causing extensive damage to the crops.



  • Insect biologists have long since known that the locust is by nature a recluse and a singleton, not mixing with others in the same group, Yet, when the harvest season arrives, these singletons team up with others as an army of swarms to attack plants for food.

  • It is important to know the mystery behind the biological mechanism by which this sociological transformation occurs.

  • Researchers showed that when solitary locusts happen to come near each other (looking for food) and happen to touch each other, this tactile stimulation causes their behaviour to change. 

  • This mechanical stimulation affects a couple of nerves in the animal’s body, their behaviour changes, leading to their coming together. And if more locusts come nearby, the crowding starts, and what was once a simple looking insect becomes larger in size and shape, and its colour and morphology changes.

  • Researchers showed substantial changes in some molecules that modulate the central nervous system of the locust, the most important among them being serotonin, which regulates mood and social behaviour.

  • Serotonin is indeed responsible for swarm formation. During research, they did a lab experiment wherein they placed locusts in a container one by one, and as the numbers increased, the coming together triggered mechanical (touch) and neurochemical (serotonin) stimulations to make crowding (‘gregarisation’) occur within a few hours.

  • Interestingly, when they started adding substances that inhibit the production of serotonin (for instance, molecules such as 5HT or AMTP), the crowding was significantly less. 

  • The insecticides (mainly malathion) sprayed on the swarms need to be looked at for side-effects. Though many studies have cleared it as not very harmful, we need to work on biopesticides which would be environmentally and animal/human health-friendly, using natural and animal products of India.

  • The potential method of prevention of locusts attack is to spray serotonin inhibitor molecules as the swarm begins to form so that the number keeps dwindling and pose far less threat.