> 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.
Instances of 'inborn intelligence' never cease to amaze me. How in the world do the larvae know in which order to eat the organs?!
If you have an instinct that is pretty low-level (say, pulling your hands away from a hot object), you could argue that your biology has been selected by evolution to respond in a particular way to that stimulus. I can also understand adults exhibiting a higher-level of intelligence - they could have learned it from their community or from direct experience. But tabula rasa minds exhibiting complex intelligence is just mind boggling.
Suppose you have two variations of a gene; one produces larvae that prefer the taste of a vital organ, and eat that one first. The other variation prefers the taste of a less important organ, eating that first and eating the important organ only when it has exhausted its preferred option. If the second one is on average 5% more likely to complete its growing before the roach dies and its food supply rots, the second variation is likely to displace the first.
Why would larvae eat only one organ at a time in the order of taste preference in the first place? Well if two variations of a gene exist, and one produces larvae that are not picky and damage many organs while feeding, while another produces larvae that are picky and thereby confine their damage to.one organ at a time, then if the second behavior is more successful it will begin to replace the first.
The central.message of modern Darwinism is the accumulation of small changes can lead to big evolutions. Obviously I cannot say what the exact mechanism of this instance was but what I gave are examples of the types of incremental changes that may have contributed. Your incredulity is based on a straw man argument: you ask how does the animal know what the right order is, as if that had to come all at once ex nihilo.
Let's first start by verifying that there actually exists such behaviour - there are no citations for larvae lifecycle part in Wikipedia and I couldn't find any reference in papers.
Maybe larvae just consumes a little of every organ it can get to. The whole story about it consuming non-essential organs first seems quite fishy - how many of those do cockroaches have anyway? Even if that's true, after eating away few organs you pretty sure to get organism failure no matter what order. Doesn't seem very smart strategy to me.
Wow. When I was a kid I was fascinated by watching bugs for hours, I even kept (and fed by capturing mosquitoes) garden spiders with their eggs in a plastic box, just to watch the spiders catch the prey and the egg hatch those dozens of litltle spideys.
But the one mysterious bug that I knew nothing about was this one. My parents couldn't tell me what was it, nor it appeared in any of my books and magazines...but I was completelly fascinated to see it carrying roaches around at my grandma's front yard. At the time I thought the green fella was hypnotizing the roach then "riding" it to it's place for dinner.
You can't imagine how happy I am to finally learn the name of that bug and what in the world he did with the roaches, thank you!
The comment thread on this article is over 200 posts. Mostly a heated creationist vs evolunist debate, but there is some interesting reading in there. It is hard not to ponder how such a complex set of behaviors came to be through natural selection alone. However, one comment that I found particularly on point is posted below:
"I have a suggestion for how this evolved. The initial sting to the cockroach would obviously make the cockroach's escape part of its brain light up like crazy. If the wasp then goes to find the most active part of the cockroaches brain, i'd imagine this would be the escape area. I believe there are simple rules which build up to create complex systems. These simple rules, like the active neuron sensor, help to create shortcuts to how a creature evolves. If you look at the recent darpa challenge, involving the teaching of a car how to drive across unfamiliar terrain, it managed to convince the team it was working by using just the rule of keeping the grass equally distant on the right and the left. It hit a bridge and swerved so the guy onboard had to grab the wheel! But the point is simple rules can lead to complex seeming actions." Posted by: Rob Levy | February 4, 2006 4:28 PM
Researchers believe that the wasp chews off the antenna to replenish fluids or possibly to regulate the amount of venom because too much could kill and too little would let the victim recover before the larva has grown.
I don't understand either of those explanations. Do roach antenna have fluids in them? How does chopping off antenna regulate venom which is already in the roach's brain? Does anyone get this part?
Wasps are amazing creatures. well over 100,000 species of them are parasites. Here's another complex insect parasite video involving caterpillars that stowaway in ants nests and the wasps that lay eggs in them, from Attenborough's Life in the Undergrowth BBC series: http://www.youtube.com/watch?v=GCo2uCLXvhk
I have to say, the world around us has some scary creatures in it. This, of course, being one high on that list. Definitely fodder for some terrifying nightmares.
Can someone with state-of-the-art knowledge of biology explain how in the world something like this could have evolved?
It was my rudimentary understanding that Lamarckian inheritance had been debunked; how else then could such precise knowledge of a cockroach's neurological functions have been passed on to the subsequent generation from the primary generation whence such a technique was first employed?
I don't have state-of-the-art knowledge of biology, but you'll note from the article
While a number of venomous animals paralyze prey as live food for their young, Ampulex compressa is different in that it initially leaves the roach mobile and modifies its behavior in a unique way.
This suggests to me that the ancestors of this wasp would simply paralyze the roach and lay eggs inside, and this behaviour evolved from that.
This suggests to me that the ancestors of this wasp would simply paralyze the roach and lay eggs inside, and this behaviour evolved from that.
That would be backwards evolution.
From the scienceblog link:
Amuplex is not technically a parasite, but something known as an exoparasitoid. In other words, a free-living adult lays an egg outside a host, and then the larva crawls into the host. One could easily imagine the ancestors of Ampulex as wasps that laid their eggs near dead insects--as some species do today. These corpse-feeding ancestors then evolved into wasps that attacked living hosts. Likewise, it's not hard to envision an Ampulex-like wasp evolving into full-blown parasitoids that inject their eggs directly into their hosts, as many species do today.
This reminds me of phorid flies, the natural enemy of the fire ant. The larva of a phorid fly eats its way into the head of the ant, decapitates the ant by dissolving its neck with enzymes, then cocoons in the head. http://en.wikipedia.org/wiki/Fire_ant#Natural_predators
Okay, now that you know... just start counting the number of times other people discover this for the first time and feel the urge to post it either here or on Reddit. Not that I blame you at all, this is pretty amazing stuff...
I recommend the book "Parasite Rex" by Carl Zimmer for those who are fascinated by this sort of thing. The book discusses several interesting and creepy parasites.
I believed that Alien was inspired by The Voyage of the Space Beagle, but Dan O'Bannon (the screenplay writer) denied it: "I didn't steal Alien from anybody. I stole it from everybody!"
So long as their stingers remain unable to penetrate the human skull or spinal cord, we're safe. Once they figure out how to do that though, every man for himself!
Instances of 'inborn intelligence' never cease to amaze me. How in the world do the larvae know in which order to eat the organs?!
If you have an instinct that is pretty low-level (say, pulling your hands away from a hot object), you could argue that your biology has been selected by evolution to respond in a particular way to that stimulus. I can also understand adults exhibiting a higher-level of intelligence - they could have learned it from their community or from direct experience. But tabula rasa minds exhibiting complex intelligence is just mind boggling.