Some of the action horror films that used “zombie” theme had been recorded as “Box office” or popular categories. Maggie (2015), Shaun of the dead (2004), Dawn of the dead (2004), you listed. Do you think zombie really exist or it is only science fiction? I have a story!
It was September 2009, after seven up to nine hours walking through a pristine forest, I found a unique creature. It is a dead ant that bites the vain of the leaf with some fruiting bodies of fungus on its body. What a frightening thing. I do not give much attention because I have to conduct Orangutan (Pongo pygmaeus wurmbii) nest count project for next four of five days. Luckily, one of my colleges took a photo of this ant.
When I run another project in the different location at the same park several months later, I find dead ant with similar condition but concentrated in a large number, like a graveyard. I have not counted it, but I am pretty sure it should be hundreds of ants or more. I also found this creature in several locations in my experience work as ecosystems controller in Gunung Palung National Park, West Kalimantan, Indonesia. My attention grew up because these ant died in the similar condition. They are same species, bite on or under main vein of the leaves, face their head to the same direction, less than 50 cm from ground and similar fungus grew from their head and body. This is very precise location. Who can do this or are that ants “inherent” such way of death from their ancestors? I started to ask some researcher and do a little bit online research. Finally, I found that this is not a novel, Alfred Russell Wallace in 1859 found this features in his travelling notes from Sulawesi, Indonesia (Hughes et al., 2011).This is an ant species that was hijacked by the specific fungus to do its favor.
The fungus is Ophiocordyceps sp, known as zombie fungus or just call Cordyceps while the ant comes from the genus of carpenter ant (Camponotus sp). Several studies, mostly in Thailand and Brazil have been done to understanding this process, such as by Hughes et al. (2011), Evans et al. (2011) and (Andersen and Hughes, 2012).
Harmon (2009) briefly described these process as:
You are a fungus that can only flourish at a certain temperature, humidity, location and distance from the ground but can’t do the legwork to find that perfect spot yourself. Solution: hijack an ant’s body to do the work for you—and then inhabit it.
However, carpenter ant is a canopy-dwelling species and travel in the forest floor in the certain trail within 3-5 meters of their nest in the tree (Hughes et al., 2011). So how to make this ant goes down and bite the leaf that approximately 25 cm above the ground? In Thailand, Andersen and Hughes (2012) found it is 25.20 ± 2.46 SE cm, while Hughes et al. (2011) found ca. 25 cm above the ground. Well, this is why cordyceps fungi “control the behaviour of the host before killing it” (Evans et al., 2011). Another name of this fungi is the brain-manipulating fungus.
I am not good in the summary process, especially for this complicated tiny manipulating process. However, this is what I found from several scientific papers. The process started with sporulation phase when microscopic spores that dropped from a fungus fruiting body, land on the ant which were walking on the floor of the rainforest. Next, the spores are breaking the ant exoskeleton using mechanical pressure and enzymes. After that, yeast spread in the body and produce compounds that controlled ant’s brain. After two days, like a zombie, the ant is driven from canopy to the precise location for a fungus to grow. The order is clear: behind the leaf and roughly 25 Cm above the ground.
The next order is to make “lock-Jawed” position or “death-grip” by bites the vain of the leaf with their mandible to secure the body along the process. Once set in, fungus damage the connection in the muscle fiber that controlled the mandible. At the final stage, fungus killed the ant and growing hyphae and mycelia. When fungus ready to reproduce, they producing fruiting bodies from ants head and releasing spores, creating 10 square feet killing zone for other ants.
Is it important for biodiversity conservation?
In ENVS3039/6024 class, we had learned that biodiversity divided at 3 level which are genes, species, and ecosystem. In this interaction, we can understand several items. Firstly, we got a new knowledge about carpenter ants (Componotus sp) and also zombie fungi (Ophiocordyceps sp). It is urgent to understanding tropical systems since tropical rainforest are fast disappearing (Evans et al., 2011). Secondly, we understanding that this fungus could balance the ant population which sometimes could be eight million individual on a single ha (https://www.youtube.com/watch?v=XuKjBIBBAL8).
Since the fungi only found on certain condition it also could be used as the indicator of the disturbance in the tropical rain forest. I never found this relationship at logged area in Gunung Palung National Park. This relationship has a potential value in chemistry or medicine. For instance, Tibet’s golden “worm” or caterpillar fungus is famous as expensive medicines to alleviate back pain, impotence, jaundice, fatigue up to tuberculosis, hepatitis and anemia (National geographic). This is the result of zombie process between Ophiocordyceps sinensis and moth (Thitarodes sp). However, extensive research is needed.
So based on the story above, the zombie interaction exist in the tropical forest. In term of biodiversity, we should look the interaction between species within ecosystem scale.
That’s all from me. Thanks for reading
Ibrahim Sumardi/ U6130746
ANDERSEN, S. & HUGHES, D. A. 2012. Host specificity of parasite manipulation. Communicative & Integrative Biology, 5, 163-165.
EVANS, H. C., ELLIOT, S. L. & HUGHES, D. P. 2011. Ophiocordyceps unilateralis: A keystone species for unraveling ecosystem functioning and biodiversity of fungi in tropical forests? Communicative & Integrative Biology, 4, 598-602.
HARMON, K. 2009. Fungus Makes Zombie Ants Do All the Work. The Scientific American, 31.
HUGHES, D. P., ANDERSEN, S. B., HYWEL-JONES, N. L., HIMAMAN, W., BILLEN, J. & BOOMSMA, J. J. 2011. Behavioral mechanisms and morphological symptoms of zombie ants dying from fungal infection. BMC Ecology, 11, 13.