Ampulex and the cockroach slave: another Zimmer zinger

Karl Zimmer is a great help to those on diets. Read his articles just prior to lunch.

The Wisdom of Parasites. The Loom: A blog about life, past and future

... As an adult, Ampulex compressa seems like your normal wasp, buzzing about and mating. But things get weird when it's time for a female to lay an egg. She finds a cockroach to make her egg's host, and proceeds to deliver two precise stings. The first she delivers to the roach's mid-section, causing its front legs [to] buckle. The brief paralysis caused by the first sting gives the wasp the luxury of time to deliver a more precise sting to the head.

The wasp slips her stinger through the roach's exoskeleton and directly into the cockroach's brain. She apparently using sensors along the sides of the stinger to guide it through the brain, a bit like a surgeon snaking his way to an appendix with a laparoscope. She continues to probe the roach's brain until she reaches one particular spot that appears to control the escape reflex. She injects a second venom that influences these neurons in such a way that the escape reflex disappears.

From the outside, the effect is surreal. The wasp does not paralyze the cockroach. In fact, the roach is able to lift up its front legs again and walk. But now it cannot move of its own accord. The wasp takes hold of one of the roach's antennae and leads it--in the words of Israeli scientists who study Ampulex--like a dog on a leash...

We have insufficient respect for the Emergent Designer (ED) -- the pseudo-deity of evolution. The ED is not a cuddly sort. Its humor is bleak indeed.

How many human psychiatric disorders (think OCD) are the result of adaptive mutations that compensate for a parasitic influence, but subsequently become disorders when the parasite is absent?