It just bugs me….(sorry)

Posted: October 8, 2013 in Arthropods

Have you ever thought about all the lies that you were taught as a kid?

Now, I’m not talking about you if, say, you went to school under the Taliban. There, you were undoubtedly taught that America is the embodiment of all evil; that stoning homosexuals to death or burying them alive is the most fun you can have in a sports stadium, and that if a girl wants to go to school, a wholly reasonable approach is to shoot her in the head. All of these, you may notice, are kind of completely untrue.

No, what I mean is the well meaning lies we were all taught about in primary school. Like, for example, ‘everyone’s opinion should be respected’. Why teachers even mention this is completely beyond me. Firstly, kids are stupid, and their opinions are thus completely worthless. Secondly, a quick glance at a comment thread almost anywhere on the internet, or a conversation with someone who believes in homeopathy or creationism or whatever, kind of shows that actually a great many people have opinions which should not be respected at all. Or ‘everyone’s good at something’, which again is utterly untrue. Quite a lot of people are good at literally nothing; although I guess this is a harsh lesson to teach to a group of seven year olds. Harsh, but I would argue necessary.

But of course, the real corker is ‘never judge a book by its cover’ or ‘don’t rely on first impressions’ or whatever. Again, I can see why kids are taught this, but it is a pretty rubbish lesson. On the whole, first impressions are backed up by second, third and eighty seventh impressions. For example, if you have a swastika tattooed on your face, I may instantly draw the conclusion, rightly or wrongly, that you are a bit of a fool. I might even go so far as to speculate you are not a nice person.

Again, I could be wrong, but I suspect this man is not great at making long term life choices.

And this does not at all bring me smoothly on to the assassin bug; or, more precisely, to the assassin bug known as Acanthaspis petax. Now, it carries around a bunch of dead ants on its back, which I think we can all agree is slightly weird. Even a teacher who has never, ever, ever judged on first impressions might agree that a bug that is called ‘assassin’ and which carries around dead corpses attached to its own body is, perhaps, an animal deserving of being named as a (drum roll please, underpaid interns) Horrific Animal of the World.

“And this weeks contestant – an insect from South East Asia which gives a new meaning to the words ‘fashion victim’… (Image credit orionmystery.blogspot)

And they’d be right.

Like all assassin bugs, it is a member of the Reduviidae family of insects, which is the largest family of Hemiptera, or ‘bugs’. Now, ‘bugs’ are defined as proboscis (formed from insect mouthparts joined together) possessing insects; basically they have a straw which they use to suck out juices. Aphids, for example, are bugs which use their proboscis to suck out plant juices. And, since we are not judging books by their covers, or in this case bugs by their names…

…we’re forced to conclude that actually, assassin bugs fully deserve their name. What they do, you see, is locate a prey insect (which varies from species to species) and seize it with their legs. The stylet (like a sharp straw) is punched into the prey. This rasps away at the prey’s insides, reducing the prey’s innards to mush. However, because nature is cold and pitiless, the horror does not end there. The bug then injects toxins and digestive enzymes, such as amylases and proteases into the prey; breaking down the prey’s body inside its own exoskeleton into a soup which the assassin bug then, simply, slurps up through its proboscis (Cohen et al 1990, Sahayaraj and Muthukumar 2011).

But lots of bugs do this! What makes Acathaspis petax so special?

Well, what it does is, rather than discard the sad, broken husk of its prey, add insult to agonising death and use sticky threads to bind the corpse (usually an ants) to its own body. For a long time, no one was quite sure why it did it; aside from a few theorists who speculated that the bug wanted to fully embrace the notion of becoming a serial killer; although once again nature has gone one better than humanity – off the top of my head, I can’t think of one psychotic murderer, real or imagined, who went around with as many as twenty of his victim’s corpses on his back.

“Carrying around all those murdered college students gives me backache”

However, in 2006 the mystery was partially solved (Jackson and Pollard 2007), after a group of scientists, presumably after taking several swigs of morale boosting brandy, found that the mountain of ant corpses on the bug’s back acted as defence against a group of spiders called salticids, which hunt almost exclusively using vision. The spiders stalked ‘naked’ bugs – i.e. bugs without a decent covering of ants – far more than they did ‘clothed’ bugs. It was theorised that the pile of dead ants on top of the bug’s back hid the shape of the bug and confused the spider. In addition, it had previously been noted (Cooper and Vitt 1991) that when a spider did jump on a bug, there was a chance the pile of corpses would fall off the bug, allowing the bug in all the confusion to escape. Finally, it may use ants in paticular for this purpose because ants tend to swarm and attack other predators – so the spider might be wary of attacking a big ball of (admittedly somewhat inert) ants (http://notexactlyrocketscience.wordpress.com/2008/01/01/assassin-bugs-deceive-spiders-with-coat-of-many-corpses/ ).

So this bug wears a suit of murdered ants to protect it from ravenous spiders which could leap at it at any moment. Gotta love Nature. (Picture credit eversostrange.com)

 

 

Oh, and just in case you haven’t lose enough sleep yet – there are some assassin bugs that feed on vertebrate blood. Sometimes, they are called “kissing bugs”, because they tend to bite on the lips or other parts of the face; making it, after a sloppy kiss from a drunken coworker who has just vomited all over the boss, the very worst kiss you can possibly have. And, to put the cherry on it, they can carry the parasite which causes Chagas disease. This can cause, in the short term, fever, fatigue, aches, diarrhoea and vomiting. In the longer term it can get worse, leading to heart problems, damage to the nervous system and recurring bouts of illness – its thought that Charles Darwin was bitten when he travelled around the world on the beagle, which explains the frequent attacks of sickness he suffered throughout his life.

All from one little bug.

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