Speaker: When it comes to bugs few sites are more impressive than this. In shear destruction nothing beats these guys. They can travel hundreds of miles a day and cover a 150 square miles or more. In one terrible binge, they can destroy the livelihood of a tenth of the world's human population. But locusts only swarm under certain conditions and for years scientists have wondered why?
Speaker: Here at Oxford University in England, experts are trying to figure out what makes this shy grasshopper, turn into a monster. Here's the secret, when locust numbers increase, something switches in this bug's brain that says swarm. See this area on hind leg. All it takes to tweak this individual into swarm mode is for me to rub its leg for five seconds, every minute for the next four hours.
Essentially I am recreating what happens in the wild when locust numbers increase and food sources dwindle, it forces solitary locust to come together, be social and rub up against each other. When that happens, these special hairs on its leg get touched. They signal to the locust brain, overcrowding, overcrowding and it's like flipping a switch. Over the coming weeks it will mold five times, change color and shape and become social, very social. When locusts swarm there could be millions of them. This individual is part of a giant eating machine. It's given up the solitary life, to join a vast society of locusts.
1988 was the last time the world witnessed a locust plague of biblical proportions. Sweeping through 20 African countries, they destroyed everything in their path. It started in the southern region of the Sahel, then the locust rapidly spread east to Morocco and Tunisia. They caused staggering levels of damage affecting millions already suffering famine from years of drought. Next the swarm swept through Sudan, heading for Saudi Arabia, Iraq and on to Iran. Today Desert Locust levels remain low, but the problem is considered so serious that centers around the world must constantly monitor their numbers.
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