Nature & Environment
Zombie Fungus Causes Ants to Die at the 'Doorstep' of Colonies to Infect More Hosts
Catherine Griffin
First Posted: Aug 19, 2014 08:59 AM EDT
A certain fungus may just turn ants into zombies--sort of. Scientists have discovered a parasitic fungus that can manipulate its victims to die in the vicinity of the colony, ensuring a constant supply of potential new hosts.
Known as the "zombie ant fungus," Ophiocordyceps camponoti-rufipedis has the ability to control the behavior of carpenter ant workers. In fact, the fungus causes the ants to die with precision attached to leaves in the understory of tropical forests.
"After climbing vegetation and biting the veins or margins on the underside of leaves, infected ants die, remaining attached to the leaf postmortem, where they serve as a platform for fungal growth," said Raquel Loreto, one of the researchers, in a news release.
After the ant dies, the fungus grows a stalk, called the stroma, which protrudes from the ant's body. A large round structure forms on the stroma and develops infectious spores. These spores are eventually discharged to the forest floor below, where they can infect foraging ants from the colony.
This fungal reproductive activity has to take place outside the ant colony. This is partly due to the ants' social immunity, which is collective action taken to limit disease spread. In this case, the researchers wanted to examine social immunity a bit more closely.
The scientists tested social immunity by placing 28 ants freshly killed by the fungus inside two nests-14 in a nest with live ants and 14 in one with no ants. In the end, the researchers found that the fungus wasn't able to develop properly in any of the 28 cadavers. In the nest with live ants, though, nine of the 14 infected cadavers disappeared, presumably removed by the ants in an effort to thwart the disease.
Then, the researchers recorded the disease in the area in general. They measured the position of manipulated ants and then plotted these locations with respect to the nest. In the end, the scientists found that infected ants essentially die on the "doorstep" of the colony.
"What zombie fungi essentially do is create a sniper's alley through which their future hosts must pass," said David Hughes, co-author of the new study. "The parasite doesn't need to evolve mechanisms to overcome the effective social immunity that occurs inside the nest. At the same time, it ensures a constant supply of susceptible hosts."
The findings are published in the journal PLOS One.
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First Posted: Aug 19, 2014 08:59 AM EDT
A certain fungus may just turn ants into zombies--sort of. Scientists have discovered a parasitic fungus that can manipulate its victims to die in the vicinity of the colony, ensuring a constant supply of potential new hosts.
Known as the "zombie ant fungus," Ophiocordyceps camponoti-rufipedis has the ability to control the behavior of carpenter ant workers. In fact, the fungus causes the ants to die with precision attached to leaves in the understory of tropical forests.
"After climbing vegetation and biting the veins or margins on the underside of leaves, infected ants die, remaining attached to the leaf postmortem, where they serve as a platform for fungal growth," said Raquel Loreto, one of the researchers, in a news release.
After the ant dies, the fungus grows a stalk, called the stroma, which protrudes from the ant's body. A large round structure forms on the stroma and develops infectious spores. These spores are eventually discharged to the forest floor below, where they can infect foraging ants from the colony.
This fungal reproductive activity has to take place outside the ant colony. This is partly due to the ants' social immunity, which is collective action taken to limit disease spread. In this case, the researchers wanted to examine social immunity a bit more closely.
The scientists tested social immunity by placing 28 ants freshly killed by the fungus inside two nests-14 in a nest with live ants and 14 in one with no ants. In the end, the researchers found that the fungus wasn't able to develop properly in any of the 28 cadavers. In the nest with live ants, though, nine of the 14 infected cadavers disappeared, presumably removed by the ants in an effort to thwart the disease.
Then, the researchers recorded the disease in the area in general. They measured the position of manipulated ants and then plotted these locations with respect to the nest. In the end, the scientists found that infected ants essentially die on the "doorstep" of the colony.
"What zombie fungi essentially do is create a sniper's alley through which their future hosts must pass," said David Hughes, co-author of the new study. "The parasite doesn't need to evolve mechanisms to overcome the effective social immunity that occurs inside the nest. At the same time, it ensures a constant supply of susceptible hosts."
The findings are published in the journal PLOS One.
See Now: NASA's Juno Spacecraft's Rendezvous With Jupiter's Mammoth Cyclone