Why do normally harmless desert locusts suddenly become aggressive and cause widespread destruction in farms?   The answer has now been obtained, and the discovery has excited the animal control world.

Desert locusts spend a large part of their lives in quiet activity, but there are times when these locusts form huge swarms and invade fields and destroy crops.   When one field has been ravaged, they move on to another field.   Such swarms of locusts are considered to be uncontrollable, to such an extent that they are named as one of the plagues that God sent to Egypt in the Bible.

However, the reason behind this abrupt violent activity of the desert locusts is now revealed.   The secret lies in the chemical serotonin, which exists in the brains of the locusts and prompts this aggressive behavior.   Serotonin has pronounced activities in the human brain also.   It can alter the mood of a person quite measurably.   It helps reduce feelings of anger and aggression, and can induce a peaceful state of mind.   It can help people who have sleep problems.   It is also used to lower levels of depression in humans.

However, in locusts, this serotonin can take the pleasurable state of mind too far.   The locusts may become hyperactive and hyper-energetic because of the substance, and may try to form swarms with destructive intent.   This is brought on by a trigger.   The trigger is usually a shortage of food in the area where they abound.   When there is a paucity of food, these locusts will begin to cluster together and form swarms.   This condition is called as their gregarious phase, during which they are the most destructive.

Scientists have also found that these locusts undergo marked physical changes when they are about to enter their gregarious phases.   They show a pronounced darkening of their body color, and their body becomes stronger.   This helps them fly over large distances.

Understanding the influence of serotonin on the behavior of locusts has caused frenzy in the animal control world.   Since an excess production of serotonin can cause locusts to participate in destructive behavior; scientists are attempting to develop a chemical that will inhibit the amount of serotonin present in the locusts so that they do not undergo this dangerous transformation.

It should be easy to develop such a chemical, because it will merely have to do the reverse of what antidepressants already do in humans.   For humans, antidepressants stimulate the production of serotonin so that they stay in a state of happiness.   For locusts, serotonin levels need to be curbed, so that they do not enter their happy destructive phase.