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Parasites That Can Control Insect Minds
Ant writes to tell us that NewScientist is running an article about an interesting parasite that apparently has the power to 'brainwash' its host. From the article: "The parasitic Nematomorph hairworm (Spinochordodes tellinii) develops inside land-dwelling grasshoppers and crickets until the time comes for the worm to transform into an aquatic adult. Somehow mature hairworms brainwash their hosts into behaving in way they never usually would - causing them to seek out and plunge into water."
Here you go.
Kinda reminds me of the plot of Resident Evil 4. :) I'm sure I read some research notes in that game that mentioned something like this as validation of the palagas taking over people's minds.
It's been known for years, if not decades, that parasites can influence their hosts' behavior to the benefit of the parasite. There are flukes (genus Leucochloridium)with a life cycle that involves being transmitted from snails to other animals—the fluke affects the snail's brain and causes the snail to become light-seeking rather than light-avoiding, which means the snails climb to the tops of plants, where they are easy prey for birds—the next host in the fluke's life cycle. More about that (and the evolutionary logic behind it) here. Another fluke has a similar life cycle involving ants, which it drives to the tops of grass blades where they can be eaten by sheep (which again become its next hosts).
A more obvious example might be rabies—animals with rabies ("mad dogs", most famously) have an irrational tendency to attack and bite other animals, unprovoked—which is how rabies is spread.
This is mentioned in a chapter intro in the book "Figments of Reality: The Evolution of the Curious Mind", by Ian Stewart & Jack Cohen.
I can't recommend that book enough.
There's a parasite that does similar things to snails. It makes the snails move to exposed places where they are visible to birds, get eaten, and the parasite gets distributed by bird excrement. Aditionally, the worm pulsating inside the eye stalk looks really gross.
...drives humans to water for pain relief- not exactly mind control, but the same result:
from Guinea Worm Disease Facts...
What are the signs and symptoms of Guinea worm disease?
A few days to hours before the worm emerges, the person might develop a fever and have swelling and pain in the area where the worm is. A blister develops and then opens into a wound. When the wound is immersed in water, the worm begins to emerge. Most worms appear on the legs and feet, but they can occur anywhere on the body. After the worm emerges, the wound often becomes painfully swollen and infected.
http://www.astdhpphe.org/infect/guinea.html
Guinea Worm Disease Facts
Have you ever noticed that anybody driving slower than you is an idiot, and anyone going faster than you is a maniac?
Found another interesting example, a parasite ( Toxoplasma gondii ) that infects cats and rats—rats are infected by eating cat feces, then the parasite affects their brains to make them less fearful, and more likely to be eaten by cats. Toxoplasma can have neurological effects in humans, too (especially those with weakened immune systems), though fortunately people tend not to get eaten by cats.
Metafilter carried a pretty fun discussion on this recently. This Scientific American article (pdf) by Robert Sapolsky is a good introduction to parasite brain control.