5 Parasites That Turn Animals Into Zombies

Some parasites are able to alter their host's brain and control the host's behavior. Like zombies, these infected animals exhibit mindless behavior as the parasite takes control of their nervous systems. Discover 5 parasites that can turn their animal hosts into zombies.

01
of 05

Zombie Ant Fungus

Zombie Ant Fungus
This photo shows a zombie ant with the brain-manipulating fungus (Ophiocordyceps unilateralis s.l.) growing out of its head. David Hughes, Penn State University

Ophiocordyceps fungi species are known as zombie ant fungi because they alter the behavior of ants and other insects. Ants that become infected by the parasite exhibit abnormal behavior such as randomly walking around and falling down. The parasitic fungus grows inside the ant's body and brain affecting muscle movements and central nervous system function. The fungus causes the ant to seek out a cool, damp place and bite down on the underside of a leaf. This environment is ideal for the fungus to reproduce. Once the ant bites down on the leaf vein, it is unable to let go as the fungus causes the ant's jaw muscles to lock. The fungal infection kills the ant and the fungus grows through the ant's head. The growing fungal stroma has reproducing structures that produce spores. Once the fungal spores are released, they spread and are picked up by other ants.

This type of infection could potentially wipe out an entire ant colony. However, the zombie ant fungus is held in check by another fungus called a hyperparasitic fungus. The hyperparasitic fungus attacks the zombie ant fungus preventing infected ants from spreading spores. Since fewer spores grow to maturity, fewer ants become infected by the zombie ant fungus.

Sources:

  • Penn State. "Zombie ants have fungus on the brain, new research reveals." ScienceDaily. ScienceDaily, 9 May 2011. www.sciencedaily.com/releases/2011/05/110509065536.htm.
  • Sandra B. Andersen, Matthew Ferrari, Harry C. Evans, Simon L. Elliot, Jacobus J. Boomsma, David P. Hughes. Disease Dynamics in a Specialized Parasite of Ant Societies. PLoS ONE, 2012; 7 (5): e36352 DOI: 10.1371/journal.pone.0036352
02
of 05

Wasp Produces Zombie Spiders

Ichneumon Wasp
Female Ichneumon Wasp (Ichneumonidae). The larvae of these wasps are parasites of a wide variety of other insects and spiders. M. & C. Photography/Photolibrary/Getty Image

Parasitic wasps of the family Ichneumonidae turn spiders into zombies that alter how they construct their webs. The webs are built in order to better support wasp larvae. Certain ichneumon wasps (Hymenoepimecis argyraphaga) attack orb-weaving spiders of the species Plesiometa argyra, temporarily paralyzing them with their stinger. Once immobilized, the wasp deposits an egg on the spiders abdomen. When the spider recovers, it goes on as normal not realizing that the egg is attached. Once the egg hatches, the developing larva attaches to and feeds on the spider. When the wasp larva is ready to transition to an adult, it produces chemicals that influence the nervous system of the spider. As a result, the zombie spider changes how it weaves its web. The modified web is more durable and serves as a safe platform for the larva as it develops in its cocoon. Once the web is complete, the spider settles down in the center of the web. The larva eventually kills the spider by sucking its juices and then constructs a cocoon that hangs from the center of the web. In a little over a week, an adult wasp emerges from the cocoon.

Source:

  • William G. Eberhard. (2001). Under the influence: Webs and building behavior of Plesiometa argyra (araneae, tetragnathidae) when parasitized by Hymenoepimecis argyraphaga (hymenoptera, ichneumonidae). Journal of Arachnology, 29(3), 354-366.
03
of 05

Emerald Cockroach Wasp Zombifies Cockroaches

Emerald Cockroach Wasp
The emerald cockroach wasp or jewel wasp (Ampulex compressa) is a solitary wasp of the family Ampulicidae. It is known for its unusual reproductive behavior, which involves stinging a cockroach and using it as a host for its larvae. Kimie Shimabukuro/Moment Open/Getty Image

The emerald cockroach wasp (Ampulex compressa) or jewel wasp parasitizes bugs, specifically cockroaches, turning them into zombies before laying their eggs on them. The female jewel wasp seeks out a cockroach and stings it once to temporarily paralyze it and twice to inject venom into its brain. The venom consists of neurotoxins that serve to block the initiation of complex movements. Once the venom has taken effect, the wasp breaks off the cockroach's antennae and drinks its blood. Incapable of controlling its own movements, the wasp is able to lead the zombified cockroach around by its antennae. The wasp leads the cockroach to a prepared nest where it lays a egg on the cockroach's abdomen. Once hatched, the larva feeds on the cockroach and forms a cocoon inside its body. An adult wasp eventually emerges from the cocoon and leaves the dead host to begin the cycle again. Once zombified, the cockroach does not attempt to flee when being led around or when being eaten by the larva.

Source:

  • Gal R, Libersat F (2010) A Wasp Manipulates Neuronal Activity in the Sub-Esophageal Ganglion to Decrease the Drive for Walking in Its Cockroach Prey. PLoS ONE 5(4): e10019. doi: 10.1371/journal.pone.0010019
04
of 05

Worm Turns Grasshoppers Into Zombies

Hairworm Parasite
This grasshopper is infected with the hairworm (Spinochordodes tellinii) parasite. The parasite is exiting through the rear of the grasshopper. Dr. Andreas Schmidt-Rhaesa, publication under GNU FDL

The hairworm (Spinochordodes tellinii) is a parasite that lives in fresh water. It infects various aquatic animals and insects including grasshoppers and crickets. When a grasshopper becomes infected, the hairworm grows and feeds on its internal body parts. As the worm starts to reach maturity, it produces two specific proteins that it injects into the host's brain. These proteins control the insect's nervous system and force the infected grasshopper to seek out water. Under the control of the hairworm, the zombified grasshopper plunges into the water. The hairworm leaves its host and the grasshopper drowns in the process. Once in the water, the hairworm searches for a mate to continue its reproductive cycle.

Source:

  • Biron D., Marché L, Ponton F, et al. Behavioural manipulation in a grasshopper harbouring hairworm: a proteomics approach. Proceedings of the Royal Society B: Biological Sciences. 2005;272(1577):2117-2126. doi:10.1098/rspb.2005.3213.
05
of 05

Protozoan Creates Zombie Rats

Toxoplasma Gondii
The protozoan parasite Toxoplasma Gondii (left) is next to a red blood cell (right). BSIP/UIG/Getty Image

The single-celled parasite Toxoplasma gondii infects animal cells and causes infected rodents to exhibit unusual behavior. Rats, mice, and other small mammals lose their fear of cats and are more likely to fall to predation. Infected rodents not only lose their fear of cats, but also appear to be attracted to the odor of their urine. T. gondii alters the rat's brain causing it to become sexually excited at the smell of cat urine. The zombie rodent will actually seek out a cat and get eaten as a result. Having been consumed by the cat eating the rat, T. gondii infects the cat and reproduces in its intestines. T. gondii causes the disease toxoplasmosis which is common in cats. Toxoplasmosis can also be spread from cats to humans. In humans, T. gondii commonly infects body tissues such as skeletal muscle, heart muscle, the eyes, and brain. People with toxoplasmosis sometimes experience mental diseases such as schizophrenia, depression, bipolar disorder, and anxiety syndrome.

Source:

  • McConkey G, Martin L, et al. Toxoplasma gondii infection and behavior – location, location, location? Journal of Experimental Biology. 2013 216: 113-119; doi: 10.1242/jeb.074153.