Table of Contents
What are parasites?
There is a whole range of organisms that live as parasites . This means that they live off another organism. We are familiar with some common parasites. These include ticks, fleas, and worms in our guts. There are some parasites that control the brain of their host. They turn that host into a so-called “zombie.”
Here are five examples of zombie parasites that will send a chill down your spine.
Cicadas make female calls when a fungus infects them
Massospora is a type of fungus that can infect its prey and take over its mind. This is why it has been given the name “zombie fungus.” The fungus uses mind control in order to get the insect to do what it wants.
Periodical cicadas are incredible insects. They emerge from underground only once in 13 or 17 years. They often fall prey to these fungi. The fungal spores land on the cicada. They begin devouring its abdomen. This provides nourishment for the fungus. Its main objective, however, is to spread its spores to others.
It releases psychoactive substances such as psilocybin, which is found in hallucinogenic mushrooms. It affects the insect’s brain and nervous system, changing their behavior. The cicadas fly around, spreading the fungal spores further.
Infected males begin to make female mating calls, attracting more males as they sing. When the males try to mate with the infected cicadas, they, too, become infected.
This gruesome discovery is tragic for insects like the cicada. However, scientists believe it could help us. We could tackle problems caused by insects. If we can use something, such as fungus, to change insect behavior, we may be able to control them. Where insects cause crop damage or harbor diseases, we may be able to combat this with fungal infiltration.
Zombie worms give snails colorful antennae, makes them mimic caterpillars
Just like “zombie fungi,” there are also “zombie worms.” Some snails can become infected by a parasite called Leucochloridium paradoxum, or L. paradoxum. This parasite invades the snail’s antennae. It changes the appearance and behavior of the snail. The antennae become swollen and colorful. They pulsate to attract birds by mimicking caterpillars.
It also reduces the snail’s ability to react to light intensity. Normally the snail would seek shelter in shadowy places. It does this to avoid predation. When infected with the parasite, however, they slither about in the light. The infected snails make their way to the tops of foliage, which makes them more visible to predators. Easily spotted, they are eaten by birds. The parasite reproduces inside the bird. Its eggs are then released in the bird’s feces. This completes the life cycle of this parasite.
Toxoplasma plays with the brain to make animals reckless
Other parasites are known to work in a similar way. Toxoplasma is a parasite found in cat feces. Pregnant women are especially warned to be careful around cats and their feces. The parasite can be dangerous for their unborn child.
Toxoplasma also has different life stages, requiring different host species. The parasite can only reproduce inside cat intestines. This is a very specific host.
Cats often eat rats. So, the parasite has found a way to change the behavior of rats, to make the rats more susceptible to predation by cats. The parasite affects the brain, making them less afraid of the smell of a cat. Usually, a rat will run and hide when it smells a cat. Being infected with Toxoplasma, however, makes the rats more bold and less likely to run from a cat. As a result, the rats are easily eaten by the cats. The ingested parasite can then complete its life cycle inside the cat’s intestines
Toxoplasma gondii has also been reportedly infecting wolves in Yellowstone National Park . These wolves become reckless and enter into the territories of other animals when infected.
Ants clamp their jaws on tree tops for fungal parasite
Parasites that take control of the mind usually do so to increase the chances of spreading. Sometimes, the parasite needs to mold the lifestyle of an animal to suit its own. Ophiocordyceps attach their spores to the cuticle of ants. The spores grow into filaments called mycelia and travel down the body of the ant, feasting on its organs. However, these fungi need to keep the ant alive at this phase. These sly fungi eat up the non-essential organs of the ant, leaving the vital organs alone for the time being. How this fungus distinguishes between vital and non-vital organs baffles scientists.
When this fungus matures inside the body of the ant, it has to release spores again to keep spreading. It is now that these fungi start to secrete chemicals that make puppets out of these ants. Infected ants climb to the top of plants and clamp their mandibles to stay in place. For one final feast, the fungi chomp on the ant’s brain and sprout on the body of the ant. At this point, the fungi release spores that are carried by the wind, which will grow on a new host.
Spider builds a web to house a wasp cocoon
A parasitic wasp, Hymenoepimecis argyraphaga, uses the spider Plesiometa argyra as a vessel for laying eggs. To begin with, the female wasp injects venom into the body of the spider to paralyze it. Next, she attaches an egg to the abdomen of the spider. The larva bores into the body of the spider as it grows. The true horror begins as the larva enters its last phase of growth. The developing larva now needs a cocoon, and what’s better than a spider at making a bed out of webbing to hold and protect it? The wasp takes charge of the spider’s mind using chemicals, and the spider builds a web like no other. It is different from the standard webs that the spooked spider builds, and it is perfectly suited to house the cocoon. The spider dies soon after, and the wasp feeds on the spider’s body until it becomes an adult.
Can these mind-controlling parasites affect humans?
The parasite affects the part of the brain associated with fear. Making the rodents fearless is key to the parasite’s survival. This effect has been shown in humans. It is thought that a third of humans are infected with Toxoplasma.
In humans, toxoplasmosis is associated with schizophrenia , suicide attempts and road rage. These are negative and devastating associations with the parasite. However, there are also positive behaviors resulting from toxoplasma infection.
Scientists found that infected individuals were less fearful. They were more likely to take risks. They reported little or no fear of failure. In the world of business and economics, this presented itself as an entrepreneurial attitude. Many of these people were successful and had started their own businesses.
Human behavior is complex, and altered by many different things. Knowing that a parasite can affect the way you behave is incredible. It can change the way you think. It can change the way you act. It’s amazing how these microscopic organisms can alter our way of life.
Glossary
Parasites: An organism living in or on another, from which it obtains its nutrients
Psychoactive: A substance that affects the brain, changing thoughts, feelings, and behavior
Spores: A reproductive cell produces by fungi, bacteria, and some plants
Schizophrenia: A mental disorder in which people view reality differently
Entrepreneurial: Taking financial risks in hope of large profits
Cuticle: Outer covering of an insect
Flesch Kincaid Grade Level: 7
Flesch Kincaid Reading Ease: 61.7
References
1. Weisberger, M. (2020) Mind-controlling fungus makes zombie cicadas lure other cicadas to a zombie fate. Found at: https://www.livescience.com/zombie-cicadas-lure-victims.html Accessed 9th September 2022
2. Goedknegt, A., Welsh, J., & Thieltges, D. W. (2012). Parasites as prey. eLS.
3. Wesołowska, W., & Wesołowski, T. (2014). Do L. eucochloridium sporocysts manipulate the behaviour of their snail hosts?. Journal of Zoology, 292(3), 151–155.
Vyas, A., Kim, S. K., & Sapolsky, R. M. (2007). The effects of Toxoplasma infection on rodent behavior are dependent on dose of the stimulus. Neuroscience, 148(2), 342–348.
4. Vyas, A. (2015). Mechanisms of host behavioral change in Toxoplasma gondii rodent association. PLoS pathogens, 11(7), e1004935.
5. Desmettre, T. (2020). Toxoplasmosis and behavioural changes. Journal Francais d’Ophtalmologie, 43(3), e89–e93.
6. Johnson, S. K., Fitza, M. A., Lerner, D. A., Calhoun, D. M., Beldon, M. A., Chan, E. T., & Johnson, P. T. (2018). Risky business: linking Toxoplasma gondii infection and entrepreneurship behaviours across individuals and countries. Proceedings of the Royal Society B: Biological Sciences, 285(1883), 20180822.
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