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Jul 30, 2007 - 7:34PM

Parasites brainwash grasshoppers..........

I know..
This must seem the most ridicules topic thread ever posted .. but,
Read on, Macduff!

Recently a friend told me about a scientific study that discovered a certain parasite brainwashed it’s host into leaping into water to drowned just for the purpose for the parasite to breed in water.
I thought she was exaggerating until I did some research…
The RaMifications of parasite influences on human behavior is long overdue….

David.

Parasites brainwash grasshoppers into death dive.
From.. New Scientist.com
Shaoni Bhattacharya
Link… http://www.newscientist.com/article.ns?id=dn7927
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.
Now Biron and his colleagues have shown that the worm brainwashes the grasshopper by producing proteins which directly and indirectly affect the grasshopper’s central nervous system.
To view a video of the parasite and grasshopper in action, which includes a brief interview, in French, with lead researcher Frederic Thomas, visit the Canal IRD website.
Selective manipulation
“It’s a very novel study, because there are very, very few papers on how behaviour actually changes,” says Shelley Adamo at Dalhousie University in Halifax, Canada, an expert in insect behavioural physiology who is familiar with Biron’s work.
“One of the reasons they are interesting is that parasites are often able to get in there and selectively manipulate behaviour," she told New Scientist. She says the eventual hope is that understanding how parasites manipulate their hosts’ behaviour – by affecting the nervous and endocrine systems –
might further the understanding of how human behaviour-systems link.
Biron and colleagues found that the adult worms – those ready to prime their hosts for a watery death – altered the central nervous system function of their hapless hosts by producing certain molecules mimicking the grasshoppers’ own proteins.
Gravity response
And grasshoppers housing the parasitic worm expressed different proteins in their brains than uninfected grasshoppers. Some of these proteins were linked to neurotransmitter activities. Others included those linked to geotactic behaviour – the oriented movement of an organism in response to gravity.
The team used an approach called “proteomics” to study the hijacking of the grasshopper’s behaviour. This technique analyses all the proteins expressed in a cell or tissue.
Biron and colleagues collected and analysed the proteins of grasshoppers (Meconema thalassinum) with and without parasitic hairworms before, during and after the grasshoppers’ suicidal plunges into a swimming pool at night-time.
“This is a unique approach and a very exciting one,” says Adamo. “This is the first time it’s been used to address this issue.”
Journal reference: Proceedings of the Royal Society

Parasitic Hairworm Charms Grasshopper Into Taking It for a Swim By NICHOLAS WADE New York Times.
Published: September 6, 2005
Parasites have long been known to influence their hosts' behavior in ways beneficial to the parasite. The rabies virus, for instance, makes animals rabid so that they bite others and transmit the virus.
An unusually specific instance of behavioral manipulation was discovered recently in a wasp that parasitizes an orb-weaving spider in Costa Rica.
The night before the wasp larva kills its host, it somehow reprograms the spider's web-building activity so that instead of its usual temporary web, the spider constructs a durable platform ideal for the larva to pupate on.
Somehow the larva reprograms the spider into executing, over and over again, just the first two steps in a five-step subroutine from the early phase of web-building.
If the larva is removed just before it can kill its host, the orb weaver will spin a platform-style web that and the following night, but revert to its usual web on the third night, as if it has shaken off some mesmerizing chemical the wasp has injected into its nervous system.
The hairworm seems to have perfected an equally intimate manipulation of its host by inducing a fantastical desire to swim, of which the grasshopper is scarcely more capable than the worm is of flying.
This is not the parasite's only trick. No one knows how, from its aquatic home, the hairworm manages to infect a terrestrial species. Dr. Thomas said he suspects that the larvae, minuscule on hatching, first infect aquatic insects like mosquito larvae and hide as cysts in their tissues.
When the adult mosquito flies away and when it dies, its body may be eaten by a grasshopper or cricket. The hairworm "will then develop, eating absolutely everything not essential to keep its host alive," Dr. Thomas said. The zombified grasshopper is reduced to just its head, legs and outer skeleton by the time it goes for its final swim.
There are some 300 species of hairworm found around the world. Their billions of larvae "will infect everything - frogs, fish, snails," Dr. Thomas said. But it is only in grasshoppers, crickets and katydids that these uninvited guests are able to usurp both the body and mind of their hosts.

Link..
http://www.nytimes.com/2005/09/06/science/06hopp.html?ex=1283659200&en=1d68c42bf9d409fa&ei=5088&partner=rssnyt&emc=rss

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Jul 30th, 2007 - 7:34 PM

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Jul 31, 2007 - 5:42AM