Zombification – An insect’s ‘jewel’

Zombies-  a stuff of nightmares …  If you ever watch it on screen, you would know what zombification means, manipulating an organism’s brain and turning it into a slave.

Before you affirm your belief that they only exist in movies, think again. Nature has been steps ahead all along, with a particular creature taking this zombification process to an extreme. It is barely a few centimeters long and far weaker than its prey. It thrives in Africa and some parts of Asia. Meet the beautiful and sinister Jewel Wasp or it can be known as the Emerald Cockroach Wasp.

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Photo credit: Animalworld

The insect’s story

To allow the female jewel wasp to lay her eggs, she needs an important ingredient, the plentiful American Cockroach. A soon as she finds her host, this gruesome ordeal begins. She attacks the cockroach in a blitz and grabs it by its armor, the pronotum. As this point, she doesn’t sting wildly as she needs her prey alive. And just like you know the back of your hand, the jewel wasp knows her prey’s nervous system well. She then delivers two stings with precision.

The initial sting targets the nerve cells in the cockroach, causing and instant paralysis of its forelegs for about a minute. This brief moment is enough for the wasp to pull out its long stinger and deliver a more delicate sting into the roach’s tiny head. Somewhat like a brain surgeon, it’s stinger is able to precisely pick two spots inside the roach’s brain to deposit a small venom there.

After completing it’s “brain surgery”, the wasp backs off and leaves the helpless cockroach.  The wasp will search for a suitable borrow for its ‘slave’.  Upon returning to its prey, the wasp bites off the cockroach’s antennae and feeds on it haemolymph, the insect’s version of blood.

After its meal, the wasp brings the roach to the burrows, without the roach showing a sign of struggle. Unlike in zombie movies, the roach is in perfect control of its ability to move as it walks normally and submissively to its tomb. The wasp then lays an egg into the cockroach before sealing its burrow and leaving the cockroach behind.

Photo credit: Journal of Experimental Biology

Within 2-3 days, the larva hatches and begins feeding on its host. After 5 days since the egg is laid, the larva feeds on the internal organs of the host until the host dies. The larva then enters a pupal stage inside the corpse. Approximately 4-5 weeks later, a mature wasps emerges from its cocoon and rips its way out of the cockroach’s abdomen and leave the burrow.

The science of zombification

Israeli scientists Frederic Libersat and Ram Gal of Israel Academy of Science and Humanities have investigated this behavior alternation process and uncovered that the venom delivered through the two stings disables very specific regions in the American Cockroach’s nervous system.

Using an electron microscope to observe the stinger more closely, they were able to locate the unusual structures at the tip of the stinger. One is used for feeling and another for tasting, both necessary to locate the targeted nervous system of the cockroach.

                                                                                     Photo credit: PLOS

Now being fully acquainted with the Jewel Wasp, do you think it the big-screen zombies will become a reality on the future?

Resources

 

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