Random Wikipedia Link of the Day

A two-fer today:

Emerald Cockroach Wasp

As early as the 1940s it was reported that female wasps of this species sting a roach twice, delivering venom. A 2003 study proved using radioactive labeling that the wasp stings precisely into specific ganglia of the roach. She delivers an initial sting to a thoracic ganglion and injects venom to mildly and reversibly paralyze the front legs of the insect. This facilitates the second venomous sting at a carefully chosen spot in the roach’s head ganglia (brain), in the section that controls the escape reflex. As a result of this sting, the roach will first groom extensively, and then become sluggish and fail to show normal escape responses.

The wasp proceeds to chew off half of each of the roach’s antennae. The wasp, which is too small to carry the roach, then leads the victim to the wasp’s burrow, by pulling one of the roach’s antennae in a manner similar to a leash. Once they reach the burrow, the wasp lays a white egg, about 2 mm long, on the roach’s abdomen. It then exits and proceeds to fill in the burrow entrance with pebbles, more to keep other predators out than to keep the roach in.

With its escape reflex disabled, the stung roach will simply rest in the burrow as the wasp’s egg hatches after about three days. The hatched larva lives and feeds for 4-5 days on the roach, then chews its way into its abdomen and proceeds to live as an endoparasitoid. Over a period of eight days, the wasp larva consumes the roach’s internal organs in an order which guarantees that the roach will stay alive, at least until the larva enters the pupal stage and forms a cocoon inside the roach’s body. Eventually the fully-grown wasp emerges from the roach’s body to begin its adult life.

Learned helplessness

In part one of Seligman and Steve Maier’s experiment, three groups of dogs were placed in harnesses. Group One dogs were simply put in the harnesses for a period of time and later released. Groups Two and Three consisted of “yoked pairs.” A dog in Group 2 would be intentionally subjected to pain by being given electric shocks, which the dog could end by pressing a lever. A Group 3 dog was wired in parallel with a Group 2 dog, receiving shocks of identical intensity and duration, but his lever didn’t stop the electric shocks. To a dog in Group 3, it seemed that the shock ended at random, because it was his paired dog in Group 2 that was causing it to stop. For Group 3 dogs, the shock was apparently “inescapable.” Group 1 and Group 2 dogs quickly recovered from the experience, but Group 3 dogs learned to be helpless, and exhibited symptoms similar to chronic clinical depression.

In part two of the Seligman and Maier experiment, these three groups of dogs were tested in a shuttle-box apparatus, in which the dogs could escape electric shocks by jumping over a low partition. For the most part, the Group 3 dogs, who had previously “learned” that nothing they did had any effect on the shocks, simply lay down passively and whined. Even though they could have easily escaped the shocks, the dogs didn’t try.