- [DAVID ATTENBOROUGH] Incredibly,
80 percent of all insects
live in jungles.
Few are more successful
than the ants.
There can be eight million individuals
in a single hectare.
(jungle sounds)
But jungle ants
don't have it all their own way.
[eerie music fades in ]
These bullet ants are showing
some worrying symptoms.
Spores from a parasitic
fungus called Cordyceps
have infiltrated their bodies
and their minds.
[eerie orchestra music]
Its infected brain
directs this ant upwards.
Then utterly disorientated,
it grips a stem with its mandibles.
Those afflicted,
if they're 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.
[eerie orchestra music]
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
specializes on just one species.
[enchanting orchestra music]
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'll be
attacked by its nemesis,
a Cordyceps fungus.
