Reading Locust grasshoppers are usually solitary and eat only very specific plants. But now and then they suddenly collapsed into huge swarms that roam the area and eat everything bald. A European research team has now discovered the trigger of this change of mind: The insects form a protein that causes social behavior and thus leads to swarming. Locust plague is already mentioned in the Bible: In addition to mosquitoes, flies and frogs, they are one of the ten plagues with which God according to the book "Exodus? the Egyptians are offended. A scenario that is still bitter reality today. In 2008, for example, a six-kilometer swarm of migratory locusts made its way across fields in Australia.

Researchers have been studying the phenomenon of swarming locusts for many years. The central question is what triggers the behavior, because actually locusts are not organized in swarms. On the contrary, they live almost self-loosely and avoid contact with conspecifics. However, within a few hours, this behavior can change fundamentally. The insects suddenly show a high activity, switching from green or brown to an often red signal color, rot together and eat everything that comes between the chewing tools.

This change of mind occurs, according to scientists around Swidbert Ott of the University of Cambridge during periods of drought. The grasshoppers no longer find enough food and inevitably move together on fertile land. "The insects suffer from frustration and hunger. The swarming serves to find together new grazing areas ?, explains the biologist Stephen Rogers.

The scientists' research suggests that the protein called protein kinase A is the mastermind for the social behavior of otherwise strict loners. In humans and many animals is this substance involved in learning processes? in the grasshopper, the protein kinase A but apparently a behavioral regulator, which showed the experiments of researchers. They used larvae of the desert locust Schistocera gregaria and adult animals under various doses of protein and documented their behavior. Result: From a certain dose, the insects formed a swarm, or changed their behavior. "So the protein triggers social behavior, which amplifies itself on the basis of positive experiences, so that the swarm stays together, " says Swidbert Ott. display

The findings could now benefit the development of control strategies against grasshopper pests: drugs that block the protein could in the future to prevent the formation of grasshopper swarms, the researchers hope.

Swidbert Ott (University of Cambridge) et al .: PNAS Early Edition, doi: 10.1073 / pnas.1114990109 © science.de? Marion Martin

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