Sir David Attenborough and the Planet Earth team discover the weird world of the Cordyceps; killer fungi that invades the body of an insect to grow and diminish the insect population. Fascinating animal and wildlife video from the BBC epic natural world masterpiece 'Planet Earth'.
SIR DAVID ATTENBOROUGH: Incredibly, 80 per cent of all insects live in jungles. Few are more successful than the ants. There can be 8 million individuals in a single hectare. But jungle ants don't have it all their own way.
These bullet ants are showing some worrying symptoms. Spores from a parasitic fungus called Cordyceps have infiltrated their bodies and their minds. Its infected brain directs this ant upwards, then, utterly disorientated, it grips a stem with its mandibles. Those afflicted that are discovered by the workers are quickly taken away and dumped far away from the colony. It seems extreme, but this is the reason why.
Like something out of science fiction, the fruiting body of the Cordyceps erupts from the ant's head. It can take three weeks to grow, and when finished, the deadly spores will burst from its tip. Then, any ant in the vicinity will be in serious risk of death. The fungus is so virulent it can wipe out whole colonies of ants. And it's not just ants that fall victim to this killer. There are literally thousands of different types of Cordyceps fungi, and remarkably, each specialises on just one species.
But these attacks do have a positive effect on the jungle's diversity since parasites like these stop any one group of animal getting the upper hand. The more numerous a species becomes, the more likely it will be attacked by its nemesis—a Cordyceps fungus.