Real zombies are among us!

It seems like science fiction, but insects can have their brains reprogrammed by fungi and even other insects! These zombies are common and may even be in your garden.

cockroach zombie

Adult wasp emerging from a dead cockroach. Illustration by Souslik B. Schmidt

We are mesmerized by the many examples of tormentors and the tormented. For example the dementor wasp (Ampulex dementor) is not very different from the soul-sucking Azkaban guards in the H
arry Potter
series. The difference is that instead of targeting escaped prisoners from Azkaban, they target cockroaches (Periplaneta americana). First, the mother wasp finds and stings the nerve in the cockroach that is responsible for the escape reflex. Her children then eat the cockroach alive over several days as it lies there helpless.

Ant zombies give us the chills. For an example of this ghoulish situation, let’s go to Brazil. Carpenter ants (Camponotus spp.) in Brazil become infected by spores of the fungi Ophiocordyceps unilateralis. These spores release substances that leave the ants disoriented. These ants are used to staying on the ground, but those that are infected  are drawn upwards, into the trees. When they are high enough in a tree they clamp down with their jaws and hang there as they are consumed by the fungi. The fungal fruiting body grows out of the back or head of the ant, releasing spores into the rain. The process starts anew.

Zombie ladybugs can be alive for days while they are being eaten. The wasp (Dinocampus coccinellae) first lays an egg on the ladybug, then the offspring feed on the internal fat of the living ladybug body. When the larvae are mature, they chew a hole to get out of the ladybug’s body and form a cocoon. Amazingly, the injured ladybug will protect the cocoon from parasites using her own body, just like a mother protecting her kids. Both the ladybug and the wasp can be found in habitats around the world, including the gardens and parks of Florida.

ladybug protecting wasps

Disoriented ladybug protecting a wasp cocoon. Illustration by Souslik B. Schmidt.

Have you ever wondered where science fiction books and movies get their ideas? Now you know. Even though zombie insects can be found everywhere, do not worry, they will not target you.  Or, so we think.

 

For more fascinating facts on real zombies, check out these sites and papers:

Dell’Amore, C. (2011). Pictures: Wasps turn ladybugs into flailing “Zombies”. Retrieved from: http://news.nationalgeographic.com/news/2011/08/pictures/110802-zombie-ladybugs-parisitic-wasps-insects/

Evans, H.C., Elliot, S.L., and Hughes, D.V. (2011). Hidden diversity behind the zombie-ant fungus Ophiocordyceps unilateralis: four new species described from carpenter ants in Minas Gerais, Brazil. Plos One. 6(3), e17024.

Gal, R., Rosenberg, L.A., and Libersat, F. (2005). Parasitoid wasp uses a venom cocktail injected into the brain to manipulate the behavior and metabolism of its cockroach prey. Archives of Insect Biochemistry and Physiology. 60, 198–208.

Milstein, M. (2007). “Zombie” roaches lose free will due to wasp venom. Retrieved from: http://news.nationalgeographic.com/news/2007/12/071206-roach-zombie.html

Prade

My guest contributor today is Patricia Prade. Patricia is a graduate student in the UF/IFAS Entomology Program.