Dr. Kevin Korus: Zombies in the garden
The zombies are coming! They stumble through the fields and forests, disoriented and searching for something. However, these zombies are not looking for brains to eat. They are looking for a place to climb and eventually die.
Ant zombies may not eat brains themselves; however, their brains are being manipulated and eaten by a parasitic fungus called Cordyceps. Spores from the fungus land on the insects and actively penetrate the cuticle and exoskeleton. They work their way (via mycelium) to the brain and release chemicals that allow them to control the actions of the insects that they infect. The fungus forces the ant (or other insect) to climb a tree or other structure so that it can create and release infectious spores that rain down on other uninfected insects. The ants are coerced into biting onto a leaf or stem before dying. The fungus then forms a spore-bearing structure called an ascocarp that protrudes from the insect’s head and eventually releases spores. It is like something out of a horror movie!
If infected ants are recognized by the colony, they will be taken far away to be disposed of to reduce the amount of infected colony members. The fungus is extremely virulent and can wipe out an entire colony if infected individuals are not recognized and disposed of.
Ants are not the only insects that are susceptible to zombification; moths, grasshoppers, stick insects and others also are hosts of Cordyceps. There are thousands of species of Cordyceps, and each species infects a specific insect host. Although the fungus is not capable of infecting humans, the premise of human zombies caused by Cordyceps infection has been explored in novels, films and video games such as “The Last of Us.”
The fungus is best suited to tropical environments and is found readily in Asia as well as South America. Researchers from UF/IFAS have discovered a species (Cordyceps javanica) that is capable of attacking the Asian citrus psyllid. This insect is the vector that transmits the bacterium involved in citrus greening disease, which has devastated Florida orange production. The fungus is so effective in killing the psyllid that it is now recommended as a part of an integrated pest-management strategy employed to battle citrus greening disease.
If you happen to find a dead ant with a strange protrusion erupting from its head, take a picture; this is just another example of nature’s wonderous pageantry!
For more information, visit bit.ly/3gFHVs2.
— Dr. Kevin Korus is the Agriculture and Natural Resources Extension Agent for UF/IFAS Extension Alachua County. Contact him at kkorus@ufl.edu or 955-2402.
This article originally appeared on The Gainesville Sun: Dr. Kevin Korus: Zombies in the garden
