Jun 11, 2008

Dutiful Host

To the left is an example of a parasitoid (something I've often called my brother) dramatically changing the behavior of its host.

In this instance, a braconid wasp injected upwards of 80 of her eggs into the flesh of a geometrid moth caterpillar. The caterpillar then went about its normal routine as the eggs developed and incubated inside of it, munching on leaves and smoking its hooka pipe.
But come hatching time, the wasp larvae burst from the caterpillar all at once--but this didn't kill the caterpillar (even though the larvae had been feeding on the caterpillar's insides). Not in the least. Instead of screaming and dying a la Alien, the caterpillar is left alive, but lives with one final directive: to protect the young wasps who have emerged only to immediately pupate.

The caterpillar denies itself all food and sustenance, suppressing its own urges at self-preservation to stand guard over the little cocoons (as seen in the photo). If any predators come too close, the caterpillar fends them off. Field studies have shown that the wasp pupae thus guarded have a 50% increased survival rate over those that aren't guarded. Once the wasps emerge from their cocoons, the caterpillar dies, just as if Ernest Hemingway had written the entire drama himself.

Thanks for the article, Mary. Life is a little less enjoyable now.

Photo source: Science Daily


Anonymous said...

OMG! Wasps have MIND CONTROL!? This has given me another reason for immediate panic whenever one comes within 10 feet of me.

Anonymous said...

This sounds a lot like where I work.

Raging Wombat said...


Patola said...

Nature, red in tooth and claw.

No wonder we're such untrustworthy, evil creatures. We came to be by the same process that created such monstrosities.

Shame to you, Mr. Darwin, for showing us our putrid faces in the mirror.

Jade said...

I just heard about these on a science podcast the other night. Are you listening to the same ones as me, Wombat? :)

More interesting information: Not all the larvae hatch and leave the caterpillar. One or two stay behind and control its mind to produce the odd "guarding" behavior.

Nature really is amazing!

Raging Wombat said...

Jade, I didn't hear that podcast, but Mary might have.

Anonymous said...

Holy crap. Nasty but fascinating.

Anonymous said...

oh, that's horrible. nature, man... wicked. just shows you the lengths nature will go to for self preservation.

Anonymous said...

Holy cow that gives me the horrors. Insects are just grossly fascinating, in an I'M SO GRATEFUL TO BE 5ft4 AND HUMAN kind of way.