In wrapping up Do Zombies Dream of Undead Sheep, authors Verstynen and Voytek introduce evident forms of zombism, or “brain hijacking” that occurs in nature. As the authors mention, zombism is fairly common in the study of entomology. The example of the Cordyceps fungus sparked my interest in seeking additional forms of real-life zombism as a product of Mother Nature (Verstynen and Voytek, 212). Further exploring the field, I came across an article titled, “Gruesome Tale: Why Wasps Live Inside Zombie Ladybugs”, by Live Science, which immediately caught my eye.
As it turns out, the parasitic wasp Dinocampus coccinellae has learned to use zombification as an evolutionary mechanism to increase reproduction of their species. By injecting a non-lethal virus into ladybug beetle Coleomegilla maculate, the wasps are able to implement a form of “mind-control”, that subjects the acquitted ladybug to serve as the official protector of their developing offspring. Initially, when the microorganism virus is first injected into the beetle, it replicates itself by feeding off of the growing larvae fluids. Once the larvae are ready to pupate, in which the larvae transform from the egg to the cocoon phase, the viral microorganism attacks the ladybug, further “zombifying” its host. The developing larvae have a tolerance to the virus, allowing the wasps to utilize this toxic alkaloid, poisoning their ladybug hosts while remaining unharmed (Abassi et al., 2001). Referred to as D. coccinellae paralysis virus (DcPV) in the national geographic article further exploring D. coccinellae, the microorganism is believed to infect the ladybug’s brain and central nervous system. DcPV not only causes paralysis of the ladybug, forcing it to serve as a stationary protector, but it also causes a tremor-like twitching behavior, further deterring potential predators.
As described in the Live Science article, researchers from the University of Montreal studied the effectiveness of the ladybug hosts and the consequent reproductive success of D. coccinellae. The researchers divided 4,000 ladybug hosts into 3 groups, all infected with D. coccinellae larvae. After development into the pupa stage, researchers manipulated one experimental group such that removing the ladybug hosts isolated the cocoons; another experimental group of cocoons was left with dead, beheaded ladybugs; the third control group was left with untouched, live ladybug hosts. All three experimental groups were then exposed to Green lacewings, insect predators of the wasp larvae, for fifteen minutes. Results showed that the un-manipulated group containing the live ladybug hosts had a 35% death rate, while the other two groups that were either unprotected or covered by a dead host, were consumed 85-100% of the time. The data from this experiment showed that the application of ladybug hosts as protection of the D. coccinellae species is extremely effective.
This example is only one of the many demonstrations of evolutionary mechanisms that utilize the behavioral manipulation of other species by “mind-control”. It further amazes me of the capabilities of microorganisms on the biological and behavioral alterations of brain functioning. Although zombies are not real, many of the zombie-like features explained in Do Zombies Dream of Undead Sheep, are evident among other species in the real world.
Al Abassi, S., Birkett, M. A., Pettersson, J., Pickett, J. A., Wadhams, L. J., & Woodcock, C. M. (2001). Response of the ladybird parasitoid Dinocampus coccinellae to toxic alkaloids from the seven-spot ladybird, Coccinella septempunctata. Journal of chemical ecology, 27, 33-43.