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Half a decade ago, I authored The Invasion of the Zombie Animals and 7 More Zombie Animals. These articles highlighted well-known examples of parasites that manipulate the minds and bodies of their hosts for survival. However, countless other parasites exhibit similar eerie behaviors, inspiring horror movies and unsettling our dreams, while their hosts endure unimaginable fates.
1. Fish Turned Zombie by a Fiery Parasite
Photograph by Solveig Schjorring.
The avian tapeworm Schistocephalus solidus relies on three hosts during its lifecycle. Eggs are deposited in a bird’s gut and expelled into water through droppings. Once hatched, larvae are consumed by copepods, tiny crustaceans, which are then eaten by stickleback fish. Here, the tapeworm thrives and grows. Through chemical manipulation, it alters the fish’s behavior, causing it to abandon its school and seek warmer waters ideal for the parasite’s growth. This solitary behavior increases the fish’s chances of being eaten by seabirds, where the tapeworm matures and reproduces, restarting the cycle.
2. Honeybees Turned Zombies Drawn to Light
Photograph by Core A, Runckel C, Ivers J, Quock C, Siapno T, et al.
The fly Apocephalus borealis, known for parasitizing bumblebees, has recently been found targeting honeybees, linking it to Colony Collapse Disorder. The fly deposits eggs inside the bee, causing it to abandon its hive and exhibit erratic behavior. Infected bees are drawn to light, similar to moths, but instead of flying, they stumble and collapse. The larvae eventually erupt from the bee’s head, leading to its death.
3. Caterpillars Transformed into Zombie “Plants”
Photograph by L. Shyamal.
The parasitic fungus Ophiocordyceps sinensis, classified as endangered, thrives in soil and relies on ghost moth caterpillars for reproduction. Infected caterpillars bury themselves in soil, positioning their heads upward. Over winter, the fungus consumes the caterpillar from within. By spring, a fungal fruiting body erupts from the caterpillar’s head, sprouting above the soil. Often, the fungal stalk surpasses the size of the caterpillar itself.
This fungus is native to Tibet and the Himalayas, where its infected caterpillar hosts are harvested and sold as yartsa gunbu for medicinal purposes. Despite the challenging collection process, a single pound can fetch up to $50,000. Overharvesting has resulted in its endangered status.
4. Spiders Turned Zombie Tailors
Photographs by Stanislav Korenko and Stano Pekár.
Czech researchers Stanislav Korenko and Stano Pekár detail the impact of the parasitic wasp, Zatypota percontatoria, on the spider Neottiura bimaculata. The wasp injects an egg into the spider’s abdomen, which hatches and feeds on its host. Mind control occurs as the larva nears maturity: the spider abandons its usual web-spinning behavior (B in the image) and constructs a specialized web (A) designed to house the wasp’s cocoon, complete with a platform and protective hood. Once the web is complete, the larva emerges, killing the spider, and spins its cocoon within the custom web (C and D).
Another species, the spider Anelosimus octavius, a tangle web spider, also falls victim to this manipulation. Normally producing simple webs, it is compelled by wasps of the genus Zatypota to build intricate tents for their cocoons. Examples of these altered webs can be seen here.
A third example of spider-wasp parasitism was explored in the second installment of this series.
5. Crickets Turned Zombie Fire Blanks
Photograph by Flickr user Tom Phillips.
The virus IIV-6/CrIV is a sexually-transmitted infection targeting crickets. This virus manipulates cricket behavior to its advantage: infected crickets exhibit heightened sexual activity, aiding the virus’s spread. However, both male and female crickets become sterile, leading them to mate incessantly until death. The virus ensures its hosts remain asymptomatic, as illness would hinder their mating behavior. If an STD could be considered intelligent, this one would be a mastermind.
6. Ants Turned Zombie Drug-addict Slaves
Photograph by Alexander L. Wild.
The Central American acacia tree and the ant Pseudomyrmex ferrugineus share a symbiotic relationship. While the tree offers nectar to the ants, the ants defend it from threats. However, this relationship is heavily skewed: the tree addicts the ants to its nectar and sabotages their ability to digest other foods. Martin Heil of Cinvestav Unidad Irapuato in Mexico discovered that ants lose their invertase enzyme, essential for breaking down sugars, rendering them dependent on the tree’s nectar for survival.
Heil revealed that the tree’s nectar contains chitinase enzymes, which permanently disable invertase. Upon emerging as adults, ants consume the nectar, and their invertase is irreversibly deactivated, binding them to the tree for life.
This scenario is akin to a shady baby food company offering to extract your decayed teeth rather than fixing them. As I always say, be wary of trees offering gifts—they might have ulterior motives.
7. Brainless Zombie Ants Continue Working and Bury Themselves
Photograph by S.D. Porter, USDA-ARS.
The parasitic fly Pseudacteon litoralis preys on South American fire ants. Using a needle-like ovipositor, the female fly deposits an egg inside the ant. The egg hatches, and the larva migrates to the ant’s brain, consuming it. Remarkably, the ant continues its normal behavior, unnoticed by the colony, despite lacking a brain. Once the larva matures, it compels the ant to isolate itself and burrow into forest debris. Finally, the fly emerges from the ant’s decapitated body, ready to reproduce.
8. The Ultimate Parasite
Photograph by Andy Potter.
Even parasitic wasps, which prey on other insects, aren’t immune to predators. Hyperparasitoids are parasites that target other parasites. As Ed Yong describes, it’s akin to a mix of Alien and Inception. This intricate tale involves a caterpillar, multiple parasites, and even a communicative cabbage.
When a cabbage is attacked by a caterpillar, it releases a chemical alarm. This scent attracts parasitic wasps like Cotesia rubecula and Cotesia glomerata, which lay eggs inside the caterpillar, ultimately protecting the cabbage. However, the same chemical also draws the wasp Lysibia nana, which parasitizes the Cotesia grub within the caterpillar. L. nana can detect which Cotesia species is present by sensing changes in the caterpillar’s saliva. It prefers caterpillars infected with C. glomerata. Some suggest C. rubecula has evolved to subtly alter the caterpillar’s saliva to evade detection by the hyperparasitoid L. nana.
Of course, L. nana itself isn’t safe, as it can fall victim to even higher-level parasites. No one is truly secure in this parasitic hierarchy.
See also: The Invasion of the Zombie Animals and 7 More Zombie Animals.
