Tuesday, October 9, 2018

Pt. 1 - These Zombies Don’t Eat Brains – But They Might Have Theirs Eaten.

Whether you like the grossness of them or not, zombies are all over pop culture these days. I know I have fallen victim to their creepy appeal. In fact, I did a little binging on The Walking Dead this past weekend. Zombie shows may be entertaining to watch, but the truly disgusting and cruel zombie stories are real. They occur all around us in nature and particularly in the insect world. Unlike the zombies that try to eat Rick Grimes and his merry band of Walker killers, zombie insects are much more like the traditional zombies in Haitian Voodoo. In Voodoo, zombies are created from people by other people in order to enslave them. They lose their autonomy over their minds and bodies and exist only to serve whatever needs their masters may have. This same dynamic is present in all zombie insects; they serve a purpose for their creator.

A zombie man in a white shirt and red tie lunging out from the page
No, not this guy - insect zombies!
In the insect world, zombies are created by many organisms, they can be other insects, nematodes, worms and viruses. With insects alone, the sheer number of insects that parasitize and take over other insects is staggering. For instance, there are over 600 species of parasitic Strepsiptera (twisted wing insects) and each one has its preferred host. Not to mention the 800 species of Conopidae flies (aka thick-headed or conopid flies) – all of which are parasitic.

The one thing that all these aggressive zombie-makers have in common is that they parasitize in the interest of reproduction. They are all trying to either feed their offspring or find a home to raise them in. They find a host and use one method or another to gain control of the body and/or mind of the insect. They then either keep it alive to feed on, cause it to commit suicide or force it to fulfill some other nefarious purpose of the parasite. How they gain the mind control is, in many instances, still not thoroughly understood. However, most researchers believe that the parasites produce neurotransmitters that somehow short out the neurotransmitters of the host. As gruesome as it seems, parasitization is extremely beneficial to the parasite (which is why there are so many of them) – it provides for their next generation and removes a resource competitor at the same time.

Now for the ghoulish details of the work of a few noteworthy zombie makers:
Close up of the head of iridescent green emerald cockroach wasp
The face of a zombie maker (Ampulex compresa)

Emerald cockroach wasp (Ampulex compressa):This lovely solitary wasp will sneak up on a cockroach and sting it in the head a couple of times. This leaves the roach alive but unable to move. After snacking a little on the roach’s antenna, it will lead the mindless roach to a burrow. Now that she has filled the cupboards with groceries, she lays a single egg case on the roach's body and seals the doomed insect up in the burrow. In due time, the wasp larvae will hatch and chew its way into the roach’s abdomen. As the wasp young continue to grow inside the roach, they feast on the living roach’s internal organs. Even while being eaten alive from the inside, the roach never struggles or moves. There is an incredible video on YouTube that shows the wasp creating its personal zombie. See it here.

Three images of a Roly Poly, or pill bug. One is all rolled up, one half rolled up and the other on its feet.r
This is why they're called Roly Polys.
Acanthocephala worms and pill bugs (aka Roly Polys): These parasitic worms enter the bodies of pill bugs and then use them as lures for birds. With the ultimate goal or reaching a bird's gut to reproduce in, Acanthocephala worms send pill bugs out to where they can be seen and eaten by birds. These normally light-hating insects not only go straight for the sun, they head to lighter colored surfaces to more easily be seen. That’s refined zombie-making!      

Tarantula Hawks (Pepsis formosa):  Technically, these large wasps don't create zombie insects. Instead, they have looked outside the insect world and developed their zombie making skills to exploit a host no one else wants to take on - the tarantula. The tarantula hawk will hunt for tarantulas and when they find one they confront it. The tarantula will rear up when challenged (which is a bad instinctive reaction in this case), allowing the tarantula hawk to run in and sting it on its abdomen. Here's
A close-up of a black moth with red wings face to face with a brown tarantula with its front legs up
A tarantula hawk subduing a tarantula
 a video of a tarantula hawk in action. In no time, the toxin will take effect and paralyze the spider. At this point, the tarantula must drag the much larger tarantula into its burrow (apparently they haven’t figured out mind control). Once there, like the emerald cockroach wasp, it will lay an egg on its host and seal it in a burrow. When the eggs hatch, the larvae will eat the non-essential organs first to keep the hapless spider alive as long as possible. Like something out of a 
B-grade horror movie, the larvae will eventually spin a cocoon around the poor spider.

An encounter between a tarantula hawk and a tarantula results is a ghastly and macabre end for the tarantula. On the other hand, an encounter between a human and a tarantula hawk is generally benign. However, should you be unfortunate enough to be stung by one, be prepared to experience an agonizing pain. The pain level that has been given second place (after the South American bullet ant) by Justin Schmidt on his Schmidt sting pain index (see below). Luckily, the pain will dissipate in about five minutes and you can go about your life with a better understanding of what the poor tarantulas suffer. I, personally, will take your word for it.

I have more fascinating and totally disgusting zombies to share with you. Check out Part Two now!

Submitted by Pam

The Schmidt Sting Pain Index - A pink chart with white lettering that shows 8 insects with level 1-4 painful stings

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