Isn't nature wonderful?

This story is a few years old, but I'd never come across it before, and it's downright fascinating:

A parasitic worm that makes the grasshopper it invades jump into water and commit suicide does so by chemically influencing its brain, a study of the insects' proteins reveal.

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.

Once in the water the mature hairworms - which are three to four times longer that their hosts when extended - emerge and swim away to find a mate, leaving their host dead or dying in the water. David Biron, one of the study team at IRD in Montpellier, France, notes that other parasites can also manipulate their hosts' behaviour: "'Enslaver' fungi make their insect hosts die perched in a position that favours the dispersal of spores by the wind, for example."

But the "mechanisms underlying this intriguing parasitic strategy remain poorly understood, generally", he says.

From the New Scientist. We might feel comforted in the fact that mammals' brains are a lot bigger than those of insects, so surely our behaviour couldn't be influenced by a parasite or pathogen. Or could it?

When Hosts Go Extinct, What Happens To Their Parasites?

Well, in many cases, of course, they go extinct themselves. But there is another possibility:

"There is a distinct possibility that declines in host species could drive parasite species to switch onto alternative hosts, which in turn could escalate the rate of emerging pathogens and parasites both for humans and our domesticated animals and plants," Dunn says. "Put simply, when a host becomes rare, its parasites and mutualists have two choices: jump ship to another host or go extinct. Either situation is a problem."

Dunn noted that the regions where new human diseases, such as bird flu, are emerging coincide with the regions where the most mammal and bird species are endangered. "We have long talked about the negative consequences of the endangerment of the species we love," he says, "but getting left with their parasites is a consequence no one bargained for."

Source. A sobering thought, no?