Econstudentlog

Squick!

Don’t read the following passage if you’re prone to having nightmares about wasps paralyzing you, giving you a lobotomy and then laying eggs on your stomach, the larvae of which will eat you – starting from the outside, then slowly hollowing you out by going into your stomach and eating your internal organs one by one in a manner that will keep you alive as long as possible – while you’re buried alive in the burrow of the wasp (some people are weird, what do I know, maybe such nightmares are normal? …wait, did my warning just increase the likelihood that someone actually will have nightmares about this? 😉 Anyway, if you do have nightmares like those, you have an interesting mind!):

“As early as the 1940s it was reported that female wasps of this species [Ampulex compressa] sting a roach (specifically a Periplaneta americana, Periplaneta australasiae or Nauphoeta rhombifolia[1]) twice, delivering venom. A 2003 study[2] using radioactive labeling demonstrated that the wasp stings precisely into specific ganglia of the roach. It delivers an initial sting to a thoracic ganglion and injects venom to mildly and reversibly paralyze the front legs of its victim. This facilitates the second venomous sting at a carefully chosen spot in the roach’s head ganglia (brain), in the section that controls the escape reflex. As a result of this sting, the roach will first groom extensively, and then become sluggish and fail to show normal escape responses.[3] In 2007 it was reported that the venom of the wasp blocks receptors for the neurotransmitter octopamine.[4]

The wasp proceeds to chew off half of each of the roach’s antennae.[1] 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. The wasp, which is too small to carry the roach, then leads the victim to the wasp’s burrow, by pulling one of the roach’s antennae in a manner similar to a leash. Once they reach the burrow, the wasp lays a white egg, about 2 mm long, on the roach’s abdomen. It then exits and proceeds to fill in the burrow entrance with pebbles, more to keep other predators out than to keep the roach in.

With its escape reflex disabled, the stung roach will simply rest in the burrow as the wasp’s egg hatches after about three days. The hatched larva lives and feeds for 4–5 days on the roach, then chews its way into its abdomen and proceeds to live as an endoparasitoid. 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. Eventually the fully grown wasp emerges from the roach’s body to begin its adult life. Development is faster in the warm season.

Adults live for several months. Mating takes about one minute, and only one mating is necessary for a female wasp to successfully parasitize several dozen roaches.

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. Several other species of the genus Ampulex show a similar behavior of preying on cockroaches.[1] The wasp’s predation appears only to affect the cockroach’s escape responses. Research has shown that while a stung roach exhibits drastically reduced survival instincts (such as swimming, or avoiding pain) for approximately 72 hours, motor abilities like flight or flipping over are unimpaired.[5][6]”

Here’s the article, here’s a direct link to the 2003 paper mentioned above.

Advertisements

October 26, 2010 - Posted by | Biology, Papers, Wikipedia, Zoology

No comments yet.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: