Ants are truly fascinating creatures. As some of Earth’s finest builders, they are a prime example of the great accomplishments cooperation can achieve. On the other hand, many people only know ants as pests and they are often in the cross-hairs of pest control experts. But there are some really interesting and bizarre facts about these industrious little insects that will definitely impress you. There are also those facts that may scare you a little. This blog post covers the latter.
Zombie Ants – the Camponotus leonardi
It’s not fun being a representative of the Camponotus leonardi ants. If we have to guess, it’s not fun to be an ant in general, but this is especially true for these guys. What is it that makes these ants so special? Oh, let’s see – maybe the fact that they can be zombified? Literally zombified! We’re not even joking.
In the past few years, the topic of the undead has been the obsession of popular culture.. We want to specify the zombified ants, in this case, are not really undead. A at least not in the technical sense of the word, because they do have vitals. However, their entire nervous system and behaviour are taken over by the invasive fungus known as Ophiocordyceps unilateralis (more widely known as the zombie fungus).
The Zombie Fungus
Ophiocordyceps unilateralis is a nasty little bugger. When it infects an ant, it makes it drop to the forest floor, where the humidity levels and temperature are optimal for fungal development. The ant has no choice but to obey. It’s entire conduct is overtaken by the fungus. It completely rewires the ant’s behaviour at a phenotypical level. The fungus changes the way ants interact with their environment by releasing chemicals, interfering with the host’s nervous system. Basically, it turns the ant into a mindless slave that does its bidding. With the fungus behind the wheel, everything the host does is for the benefit of the parasite.
Reproductive Cycle of the Fungus
After the fungus matures enough, it forces the zombie ant to climb up, lunge its mandibles in the main vein of a leaf and stay there, while the fungus ensures atrophy by destroying the connections in the muscles and affecting the fibres at a cellular level.
When this is done, the fungus starts to affect the exoskeleton in order to ensure its reproduction. Having fortified the ant’s now living corpse, it releases agents that deal with potential competition, after which it springs fruiting bodies from the ant’s head. These fruiting bodies release the spores, allowing the zombie fungus to reproduce and begin the cycle all over again.
Тhat being said, the ants aren’t completely defenceless. First off, there are other fungi that attack the Ophiocordyceps unilateralis and kill it (hence the biological warfare with the zombie fungus trying to ward off competition before releasing its spores). Furthermore, ants have developed the ability to “detect” infected ants and when of their fallen comrades begin to exhibit symptomatic behaviour, they tend to stay away from them.
The Camponotus leonardi are not the only ants affected by the zombifying fungus, though they are the most common species and the only one that’s truly been investigated. Since the fungus evolves alongside ants, it stands to reason that it does not only affects them, but other close relatives, as well. It makes sense from a morphological perspective. However, other ants can still succumb to the fungus’ deadly spell, though the specific chemicals that control behaviour seem rather ineffective. The fungus kills the host, nonetheless.
However, other types of Ophiocordyceps have been discovered that affect different kinds of ants. This is a relatively new discovery, so things are still a bit hazy. What we know is that different fungal types target different types of ants, which leads us to believe they tend to co-evolve. This biological arms race is a true testament to nature’s complexity. It’s humbling to realise how little we truly know.