The Judas Breed

            In Guillermo del Toro’s flawed, but fascinating 1997 movie Mimic, man is no longer at the top of the food chain.  When an epidemic of incurable disease known as Strickler’s threatens to kill an entire generation of children in New York City, entomologist Susan Tyler conceives of a bold and ambitious plan by genetically-engineering a new species of insect called the Judas Breed. One that works as a biological counteragent to eradicate the disease’s carrier, the common cockroach.  When the first deployment of the Judas Breed results in the death of hundreds of cockroaches and no new cases of Strickler’s, they seem to have done their job.  But as Jeff Goldblum says in Jurassic Park, “life finds a way,” and the Judas Breed not only circumvent their genetically-programmed destruction, but evolve to where they can mimic the movement and physical appearance of humans, allowing them to prey on and devour us without realizing it.

            But what about the science in Mimic.  How close does it come to real depictions of insect mimicry.

Wait, That’s Not An Ant

            Mimicry is a biological advantage that not just insects, but arachnids, mammals, and mollusks, just to name a few, use for either defense, attack, or camouflage.  In the case of the Judas Breed, they use what is called aggressive mimicry, which is when a predator imitates a third party that its prey does not regard as threatening.  This could be either another member of the prey’s species or the organisms that the prey itself consumes.  It’s sometimes referred to as the “wolf in sheep’s clothing” method, and aggressive mimics accomplish this through a number of ways. 

            The ant nest beetle (Paussus favieri) mimics the same noises made by Moroccan ants (Pheidole pallidula) by rubbing its legs against ridges on its body, creating the same noises made by soldier, worker, and queen ants, as well as growing large antennae that release chemicals similar to what ants produce in order to get into the ants’ colonies to find a mate and lay eggs without being detected and totally dismembered by soldier ants.  Once the beetle’s eggs hatch, the ants cannot distinguish the beetle larvae from ant larvae.  The ants in the colony raise and feed the beetle larvae as if they’re their own. Once they reach adulthood, the beetles, as Carl Zimmer writes in a 2015 piece for the New York Times, “…sink their jaws into ant larvae and freshly moulted adults in order to drink their body fluids.”

            Similarly, rove beetles evolved to mimic the coloration, body shape, smell, and behavior of army ants in order to blend in with ant society in order to feed on the young.  The beetles are so successful at this mimicry that they even go on marching raids with the ants.  Ants are blind, and use both chemical and tactile signals to distinguish their fellow colonists from other insects.  So, when rove beetles emit the same chemical scent and possess the same body shape as the ant, they can slip by undetected.  This is actually not a type of mimicry, but the result of convergent evolution, which is when multiple species evolve a similar trait in similar environments, which in the case of the rove beetles includes at least 12 species.  Rove beetles may have at first simply preyed on the army ants, and then gradually evolved over the course of multiple generations to be able to become a part of the army ant colony.  So much so that they’re nearly indistinguishable from the ants. According to a 2017 NewScientist article about the rove beetle and their biological advantage, “‘What we found is that multiple times, the ancestors of these rove beetles adapted to life inside army ant colonies…Each time, their body shape and behaviour underwent the same radical changes.’”

            Finally, we turn to the assassin bug (Stenolemus bituberus).  This unsettling-looking insect that looks like something out of a science fiction movie is a slow, methodical killer that preys on spiders by mimicking their prey caught in their web.  Once an insect has become ensnared, their every slight movement creates vibrations in the web that the spider can feel and knows that it’s caught something.  It then moves in for the kill.  This is where the assassin bug comes in.  By gently plucking the silk of the web with its front legs it creates similar vibrations which causes the spider to come out from hiding.  Spiders are incredibly dangerous and can quickly turn the tables on assassin bugs, killing and eating them, if they’re not careful.  It’s why the assassin bug tries to keep its distance and only mimics the movements of the spider’s prey.  Once the spider has been lured out and is within striking range, the assassin bug will attack and seize the spider with its forelegs, stabbing it repeatedly with its proboscis until it dies, usually 10 seconds later.

            So, the next time you find yourself alone on a subway platform in lower Manhattan and there seems to be a strange-looking person with funny shoes standing in the shadows who keeps staring at you, run.

Art by Tchaka Sikelianos

Sources Used

Animalogic.  “Mimicry: A World of Imposters.”  YouTube, 19 April 2019. https://www.youtube.com/watch?v=AyzsbSJyRKs

Choi, Charles Q.  “Assassin Bugs Turn Webs Against Spiders.”  LiveScience.  26 October 2010.  https://www.livescience.com/8834-assassin-bugs-turn-webs-spiders.html.  Accessed 8 February 2020

Coghlan, Andy.  “Sneaky beetles evolved disguise to look like ants, then eat them.”  NewScientist.  9 March 2017.  https://www.newscientist.com/article/2124050-sneaky-beetles-evolved-disguise-to-look-like-ants-then-eat-them/ Accessed 7 February 2020

The Editors of Encylopaedia Britannica.  “Aggressive mimicry” Encylopaedia Britannica, Encylopaedia Britannica, Inc.  6 December 2018.  https://www.britannica.com/science/aggressive-mimicry.  Accessed 6 February 2020

Zimmer, Carl.  “A Social Parasite’s Sophisticated Mimicry.”  New York Times.  16 July 2015.  https://carlzimmer.com/a-social-parasites-sophisticated-mimicry-98/.  Accessed 8 February 2020

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