Wednesday, February 9, 2011

Total control freak

While trekking in northern Johore, we stopped by to examine a body by the side of the stream....


It belonged to the Giant Forest Ant (Camponotus gigas), one of the largest species of ant in the world, reaching close to 3cm.

Infected by an Ophiocordyceps fungus (O. unilateralis or similar) and banished from its nest, it was brainwashed to climb to a higher staging area and anchor itself by biting on the leaf blade of a lallang. Here, it was summarily executed - fruiting bodies punched through the exoskeleton like Howitzer-guns, ready to fire spores which eventually fall to the ground to infect passing victims.

Interestingly, in spite of the fact that the spores mostly make contact with the host on the ground, Camponotus leonardi, a tree dweller, was found to be the principal host in Thailand. I would have assume that this terrestrial giant forest ant would be a more suitable host.

Researchers had reported very surprising things about this fungus, like the fact that the it is very exact in its manoeuvre - dead ants invariabily face northwest, about 25 cm from the ground at sites with at least 90% humidity. Strangely, if the ant is allowed to die in its nest, the survival rate of the fungus is zero. Though it turns vital organs of the ant to mush, it also protects its turf by growing into the cracks and niches of the exoskeleton to prevent entry of microbes competing for its food and fortress.

Isn't it weird that a lowly organism can so brilliantly take over the body and psyche of such a complex (relatively speaking) animal ?

References :
D.P.Hughes et al, The Life of a Dead Ant: The Expression of an Adaptive Extended Phenotype. The American Naturalist, V173, no3 September 2009.
D.P.Hughes et al, Graveyards on the Move: The Spatio-Temporal Distribution of Dead Ophiocordyceps-Infected Ants
PDF
Also search for the brilliant BBC footage with commentary by my fav Sir David Attenborough
Here's my previous post of this subject - which infected a fly in Singapore.

7 comments:

Hermes said...

Wow. Definately strange. Makes you think about spores being 'inanimate'.

Titania said...

Hortlog, this is amazing...If Shakespeare had known about this he would have included it in his Witches Chant. Nature works silently, sometimes deadly; each on its own.

Hort Log said...

haha well said Trudi.

Isa.. said...

Sorry to trouble you, but this sounded scary so I decided to watch the David Attenbrough clip. I can't find it though. Do you know its name?

Hort Log said...

Isla, posted a link at my comment in your blog, and attached the link here as well.

Isa.. said...

Ok thanks a lot.

KY said...

You seem to know everything. Thanks for the infor. Very amazingly interesting.

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