Migratory grasshoppers are the most widespread grasshopper species
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Locusts are known to swarm massively, devour crops, and can destroy enough food to feed 35,000 people in a single day. They are also cannibals, so huge swarms pose a danger to the insect itself, but researchers have found that migratory grasshoppers produce pheromones that drive their swarm mates out of their scent.
In the animal kingdom, cannibalism is very common. “Do not eat [members of your species] Bill S. Hanson of the Max Planck Institute for Chemical Ecology in Germany says. “If you don’t eat what’s around you, you’re wasting energy.”
Recently, scientists determined that cannibalism helps drive post-apocalyptic swarms of locusts. “They actually start eating each other from behind,” Hanson says.
Cannibalism can even drive flocks of young flightless birds, says Iain Couzin of the Max Planck Institute for Animal Behavior in Germany. “Once the flock takes off, it becomes even more difficult to control. It’s like wildfire,” he says.
Hanson and his colleagues hypothesized that locusts must have evolved measures to discourage neighbors from eating locusts when they gather in large swarms. The researchers began by looking for odorant compounds produced only by locust larvae (migratory grasshopper) under crowded cage conditions with up to 250 individuals per cage. They identified 17 grasshopper-produced compounds using a technique called gas chromatography, which separates different compounds in a sample. This includes phenylacetonitrile (PAN). PAN was already known to deter other species, such as birds, as it can be converted to toxic cyanide compounds.
To test whether PAN protects against cannibalism in young grasshoppers, the researchers used CRISPR gene editing to create a strain of grasshoppers that lacked the gene for PAN. became the target of In another line of grasshoppers, researchers disabled the olfactory receptors that detect PAN. This caused the locusts to start eating their neighbors, even those that gave off a deterrent odor.
The findings could one day be used to manage locust swarms and reduce their numbers without the need for current approaches such as pesticides. Blocking their ability to generate or detect, they say, could allow locust populations to self-regulate by eating themselves. It can also make grasshoppers more vulnerable to other predators.
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