Researchers have discovered a drug that prevents locust infestation. Since the beginning of history, outbreaks of locusts have been reported, destroying all vegetation and endangering the food security of millions of people in Asia and Africa.
But the recent discovery of a pheromone secreted by insects to avoid being eaten in swarms could open the way to curbing these pests' voracious appetites.
Bill Hansson, director of the Max Planck Institute's Department of Evolutionary Neuroethology, told AFP that the latest report, published in Science, builds on these findings, according to previous studies showing that swarms are actually controlled by threat of being eaten by other locusts rather than cooperative behavior.
Although it disgusts us as modern humans, cannibalism is common in nature, from lions that kill and eat other people's cubs to foxes that use their deceased relatives for food.
It is assumed that cannibalism plays an important ecological role for locusts.
Because of their numerous variations and distinctive behaviors, migratory locusts (Locusta migratoria) were once believed to be an entirely different species.
They spend most of their lives in a 'solitary' phase, where, like timid grasshoppers, they close in on themselves and consume relatively little food.
However, when population densities increase due to rains and short-term favorable mating conditions, followed by food shortages, they experience significant behavioral changes as a result of a burst of adrenaline, which makes them more aggressive, causing them to gather in herds.
According to a 2020 study by Iain Couzin of the Max Planck Institute for Animal Research, this is known as the "stingy" stage, and fear of cannibalism helps the herd move in the same direction, from an area of lower food density to an area of higher food density. is believed. According to Hansson, “grasshoppers eat each other from behind.”
Therefore, if one stops moving, the other will eat it, making us believe that every threatened animal has a defense mechanism.
Hansson's team first proved in the lab that what Couzin saw in the field in Africa (the trigger point was around 50 in a cage), cannibalism rates do indeed increase as the number of "sluggish" locusts kept in a cage increases. These painstaking experiments took four years to complete.
After comparing the odors produced by solitary and gregarious grasshoppers, they discovered 17 odors that were only present during the gregarious phase.
In behavioral tests, one of these chemicals - phenylacetonitrile (PAN) - was discovered to deter other locusts.
Emitting PAN seemed appropriate as a signal to encourage others to withdraw, because PAN is involved in the production of hydrogen cyanide, a potent toxin that greedy locusts occasionally produce.
To confirm the discovery, they genetically modified the locusts so they could no longer produce PAN, making them more susceptible to cannibalism.
They examined dozens of the locusts' olfactory receptors for additional evidence before deciding on one that is highly sensitive to PAN.
The transformed locusts developed more cannibalism after their genes were edited to stop producing this receptor.
In a linked paper published in the journal Science, researchers Iain Couzin and Einat Couzin-Fuchs claimed that the discovery helps illuminate the "complex balance" between the mechanisms that cause migratory locusts to congregate and compete with one another.
Thus, technological advances in locust control may shift the delicate balance in favor of more competition, but Hansson stressed that this is not the point: "You don't want to destroy species."
“We can gain a lot if we can reduce the size of the flocks and direct them to areas where we don't grow our crops,” he continued.
📩 08/05/2023 00:47