In Africa there lives an extraordinary tree
She is the queen of the riverbank
A monarch whose story stretches
back millions of years
In tribal cultures, have curious ways
have fueled myth and legend
They set her apart from other trees
She is a sycomore fig
Queen of Africa's trees
She appears never to flower
Yet mysteriously she fruits
several times a year
She seems to have no regard for season
and drops her leaves when she pleases
Strangest of all is the relationship
upon which she completely depends
The two partners couldn't be more different
One can withstand a river in flood
the other can drown in a dew drop
One lives for centuries, the other only hours
They differ in size a billion times over
At about 1mm long the fig wasp is so small
that it could fly through the eye of a needle
but no fig tree could exist without it
Sycomore figs are found
throughout tropical Africa
In Southern Kenya
they thrive along river banks
This is the story of one of those trees
Our African queen is a mature sycomore fig
She started life as a seed
a hundred years ago
She provides for many animals
To some, she is a hunting ground
To others, she is home
She feeds a greater variety
than any tree in Africa
that only a few even notice
Every few months, the queen
produces up to a ton of fruit
To reproduce, she must transfer pollen
to make seeds
and then disperse them inside figs
The last crop fell only days ago,
but up above she is starting again
Over the next two weeks,
the tiny buds swell to become young figs
Hidden inside each
are the queen's tiny flowers
At this stage a fig is not a fruit
but a secret garden whose delicate perfume
attracts a flock of fig wasps
Their arrival will trigger a sequence of events
that will resonate out through the bush
The wasps are all females,
laden with pollen and eggs
They must enter the fig
via the garden gate to pollinate
the flowers and lay their eggs inside
A one-way passage leads
to the secret garden which is lined
with hundreds of microscopic white flowers
Some of these flowers will become seeds,
others will be a nursery for fig wasps
The tree will surround each wasp egg
with a capsule, called a gall
which will nourish and protect it
The wasps will soon die,
but inside each hanging garden
their offspring will live on
The queen is now their surrogate mother
and will care for them until
they hatch in 2 months' time
The fig wasps aren't the only ones
to lay eggs in the tree
for a pair of grey hornbills is nesting
This female's confinement will be temporary
She seals herself into the hollow trunk
leaving only a slit
through which her mate can feed her
The swelling figs place
a big demand on the queen
To feed her wasps and grow seeds,
she needs to make sugar with her leaves
Animals that eat leaves are a major threat
If the queen loses too many,
she might have to abort her figs
The only thing more damaging
is a direct attack on the nursery
To protect her leaves and young figs
the queen pumps them up with a milky latex
which is foul-tasting and sticky
Small offenders get stuck down
and it's unpleasant enough to ensure
that others don't stay too long to feed
Sycomore figs have been under attack
for millions of years
In that time, some insects have evolved
strategies to overcome the defenses
A fig long horn beetle bites
through the veins to
disrupt the flow of latex
It starts with the main vein
and works outwards
Downstream of the damage, the flow
is cut off and the beetle can feed
The fig katydid cuts the flow of latex
by cutting off the leaf
The pink mantis is a predator
but it's still very young
and a katydid this size is
more monster than meal
The mantis can't fly so to get off the leaf
it has to get pass the green giant
Beneath the tree, the fermenting juice
in the last crop of figs attracts vinegar flies
An ideal size, the mantis still
wants to snatch a bite to eat
The male hornbill is working hard
for he now has 3 extra mouths to feed
For hornbills, nesting is always a risk
To try and plan her family for when
most food is available the female
had to lay before the rains
This year they're late, and every day that they are
delayed will make finding food a little harder
and the chicks a little weaker
To try and protect the wasp nursery from parasites
after the females enter,
the queen close the gate
and flooded the garden with an antiseptic liquid
He doesn't work against nematode worms
which used a female wasp as a Trojan horse
and stowed away in her body to get into the fig
Inside they burst out
and are now breeding to be ready to
infect the next generation of fig wasps
Outside the nursery is under attack
from parasitic wasps
They can't get in by the gate so they
drill through the long ovipositor, an egg-laying
device that works like a hypodermic
Forced deep inside, it will deposit
an egg on a developing fig wasp
The grub that hatches will k*ll
the wasp and take over its gall
The driller seems to have evolved
the perfect strategy
but over time,
even parasites can be exploited
A smaller banded wasp has an ovipositor
just as long but more flexible
The little wasps fight for access and
when the driller pulls out
the winner goes straight for its hole
It will use the same shaft
to lay its egg on the driller's
for these smaller wasps
are parasites of parasites
In the queen's battle to protect
her fig wasps her allies are ants
They will k*ll any parasites they capture
Anything they can't subdue,
they bite and sting to drive away
The ants appear to be protecting
the figs and in a sense they are
for all are attacted
All that is, except one
These tiny bug eggs should
be the ideal snack for an ant
but instead, the ants look after them
As they hatch,
the ants gather up the babies
They're nymphs of a bug called hilda
which are herded up to graze
as if they were sheep
Almost every fig now becomes a paddock
The ants are so attentive because a nymph
has hollow piercing mouthparts
that enable it to tap into the fig's sap
The sweet liquid is under pressure
so it passes rapidly through the nymph
When it comes out, it still
contains plenty of sugar
So in return for being nursemaids
and bodyguards the ants receive
the supply of sweet honeydew
The wounds made by the nymphs and
parasites are heal for the latex
that drives to form a natural rubber
The bee doesn't eat it but collects it
to take back to seal holes in its own nest
It's been two weeks since the hornbill
chicks hatched and still it hasn't rained
Now the female must break out
to help feed her family
as soon as she leaves,
the eldest chick instinctively starts
to plaster up the hole again
using droppings and debris from the nest
It will be a while before it is ready to leave
The rains arouse some that
had been sleeping for months
They will bring the expected
flush of insects
but they have come too late
for the youngest chick
When their mother left the largest
chick dominated the food supply
The chicks differed in size because
the eggs were laid a few days apart
and hatched at different times
There is a distinct pecking order,
so in lean times
the chick with the best chance of survival
gets to feed first and takes most of the food
Even now when both parents providing
the smallest dare not feed
until the larger is full
Despite clear skies, beneath the tree
it still seems to be raining
These are fig cicadas
they emerge after rain and
tap straight into the sap
Like hilda they vent what they can't absorb
But to avoid getting their wings sticky
they don't drip but squirt
From the trees' point of view
this is a major as*ault
In the fight against cicadas, the queen
needs all the help she can get
For the ants have changed their allegiance
Each time a cicada pulls out
it leaves a drop of sweet sap
which bribes the security
The ants are too busy drinking
to protect the tree
The sap is the only thing
the ants will defend
But if news of it gets back to the hive
then the bees will be back in force
At the peak of the invasion
the trunk runs with sap
and branches and leaves are sticky
with sweet drizzle
Monkeys are opportunitists
Cicadas are only around
for a few days each year
so they get their fix of sugar while they can
To begin with there's no competition
but it didn't f long for the news to spread
Fortunately for the queen the cicadas
disappear as quickly as they came
For the past 2 months she has been
making sugar to grow seeds and wasps
Inside the figs the protective fluid
has drained away
The exposed galls are no bigger than pinheads
The female wasps inside cannot hatch
yet, they must wait for a mate
Male fig wasps have powerful jaws
and a single intension
On hatching they cut through
to the c*ptive females
not to let them out
but to let themselves in
A male has no wings,
and only tiny antennae and eyes
but in one area, he's very well-endowed
His cleft chin helps guide him in
He impregnates a female before she hatches
With an organ that is so long
and flexible that some males can
mate without leaving their galls
Inside the trunk, there has been
a dramatic change in behavior
as if adolescence had set in overnight
At dawn, the eldest chick started
breaking down the door
It's time for it to leave
In the confined space the chick hasn't
even been able to stretch its wings
so if it's to fly, it will lead instinct
to kick in before it hits the ground
It is an adolescent triumph of
instinct over experience
but it will be a few days yet
before the last chick attempts it
The queen can produce up to 100,000 figs
Inside each, the female fig wasps
have enlarged the holes the males make
and are now starting to emerge
They look very different to their mates
as they have large eyes antennae and wings
all will be essential for their mission
The parasites hatch too for they will rely on
the fig wasps to help them escape from the fig
The nematode worms are trying
to snag a female wasp
They'll burrow into her body
and slowly eat her alive
but they can't k*ll her too quickly as she
is the only way they reach another fig
The male wasps' next job is to cut flowers
The white anthers contain pollen and
must be chopped down for the females
Their mission is to carry the queen's
pollen to other trees
This is why she raised them
Pollination of a queen
is exclusively by appointment
The fig wasp female scrapes out pollen
and carefully packs it into special pockets
on her breast
It is extraordinary behavior
Meanwhile, the males have started to tunnel
It will take them some hours but before they die
they must release the females from the fig
These bees are scouts sent ahead of
a swarm to search for a nest site
but it is already occupied
The baby hornbill is in danger
if a single scout gets back
then the swarm will descend on the tree
It can't let any get away
In thousands of figs all over the tree
the tiny tunnelers are about to break out
In the space of one hour in the late afternoon
millions of fig wasps will emerge
This is the final act of the males' brief lives
For them a glimpse of evening sunshine
won't signal freedom but death
After 2 months developing inside the fig
their lives have been whittled down
to an intense few hours
Now they give their lives
to set the females free
The winged courier will never feed
They can't survive more than
a few hours in the sun
and the worms inside are already
weakening them
Theirs will be a race against time
They don't hang about for good reason
The ants don't distinguish
between parasite and pollinator
but it's the price the queen pays for security
The ants kept many parasites from laying,
so ultimately more fig wasps survived
The activity attracts other players
In its bid to reach the wasps a tiny day
gecko doesn't notice a giant stick insect
it plays an important supporting role
Fig wasps can't sting
and they're so nourishing
that in order to catch them the gecko
risks going out on a limb
Sometimes that is not enough
As a last resort, to distract a predator
a gecko can jettison its tail
It's a remarkable ploy
and if the gecko stays out of trouble
then its tail will grow back
All over the tree, the queen's tiny couriers
are being intercepted
A spider cannot eat them all at once so it
wraps them in silk trapped as a living larder
For each wasp that's captured
hundreds will fly free
It will be the flight of their lives
This evening the tiny wasps will set out
in search of a fig tree
and another secret garden
Some will find trees nearby
but others will be picked up by the wind
and can travel over 100km
In the aftermath of the break out
the queen is littered with casualties
Many didn't make it or gave
their lives so that others did
One scout got away
and although the parents tried
they couldn't entice the chick from the nest
it simply wasn't ready
The queen's leaves have done their job
For the last 2 months they've been making sugar
but the wasps have flown and her seeds
are ready to be dispersed
When the wasps left the figs ripened rapidly
to become soft and orange and full of sugar
It's as if each is shouting: eat me!
Over 100 different kinds of birds eat figs
all will fly off with a cargo of seeds
Some eat little else
A green pigeon is a fig specialist that
flies miles from its nest in order to feed
The birds have waited for the banquet
and they wouldn't be frightened off
Back at its nest the green pigeon feeds
its chicks on a milk of liquid figs
In this way, the bounty of the tree
is spread far and wide
Some can smell the food from miles away
Others live close by and while
the queen is fruited visit every day
Though there's so much on offer
that the monkeys can be choosy
They discard figs that are full of parasites
With tiger beetles below, the wasps
will be lucky to get airborne
Some figs remain full of parasites
Inside them all are dying
for parasites need pollinator
males to release them
If the parasites have been too successful,
they can hatch but never leave
In this way, the parasite numbers
are kept in check
Across Africa, more animals eat figs
than any other fruit
Fig tress are so important because they
fruit outside the normal fruiting season
If they produced figs only once a year,
the short-lived fig wasps would die out
To maintain the population of pollinators
each tree needs to fruit at random
several times a year
and this benefits every one
In the heat, fig juice ferments into alcohol
and the smell attracts a thirsty clientele
The butterflies are normally shy and elusive
but drinking alcohol through a straw
has a predictable effect
The inebriated insects are lucky
as they don't taste very good and
most can still manage to fly
The queen's generosity extends beyond the tree
for those she provides for, in turn,
support others
Wherever fish gather
a crocodile is never far behind
The croc sets its trap in fast water
where the fish can't see its jaws
It won't see the fish but it will
react at the slightest stretch
As figs are the bait the croc
makes a lot of false strikes
But as in any fishing, patience is essential
Figs are sometimes eaten by people, but
occasionally the tree has something sweeter to offer
Traditionally fig wood is used to conjure fire
for it's soft and smolder as well
The wood in which the bees found sanctuary
is now being used to against them
Dry elephant dung is the tinder
To gather honey the Maasai exploit the bees'
instinctively response to smoke
It's evolved to protect the colony
in the event of forest fire
When the bees smell smoke
instead of defending the nest
they gorge on honey and then flee
In a fire it will be more important that they escaped
so they could re-establish the colony elsewhere
Normally even a single sting
triggers an attack
but with the smoke there is no reaction
The fig's flowers had nothing to do
with this honey
The queen's exclusive relationship
with her wasps
means that her flowers never saw the sun
and never had a visit from a bee
Living by water helps spread the seeds
as figs float downstream
and sprout along the strand-line
A tiny echo of the avenue they came from
It can be a one-way ticket
unless the seeds can get help
Migrating catfish carry some backup stream
A lucky few will be planted and fertilized
Strangely, no siblings grow
beneath the queen
Despite the amount of fruit that falls
Nothing geminates here
not because of shade
but because tiny seed-bugs
steal all the seeds
They are specialists that eat only fig seeds
To perpetuate the royal line
the queen needs help
to get her seeds further afield
It doesn't arrive until after dark
Fruit bats are the most important
seed dispersers
They're less agile than birds
so the queen makes access easier
by dropping her leaves
and hanging her figs clear of the branches
Each bat needs to eat half its weight
in fig pulp each night
They eat little else
and a diet of fig juice can result in
an urge that requires immediate action
Importantly for seed dispersal
a bat rarely eats in the fig tree
but carries the fig a short distance away
It doesn't eat everything
but sucks out the juice
and discards the seeds
So beneath its perch
sprout tiny fig gardens
During the night the female fig wasps
have been traveling across Africa
A few have found receptive figs by homing
in on the scent from the secret garden
To enter, the female must squeeze
through the gate
A wedge-shaped head will help pry it open
but it's so tidy that her wings and antennae
will be ripped from her
and in the final push,
she literally busts a gut
She must lay her eggs before the nematodes
she's carrying burst out and k*ll her
Her final challenge is to negotiate
a spiral valve that leads to the flowers
It might take an hour and will
need all her strength
She will be alone in the garden
for the gate is closing
others arrived too late
Inside she is in trouble
the nematodes are breaking out
She cannot last much longer
but must still lay her eggs
and complete her mission
The tiny wasp's final act is
to repay her debt to the queen
to unpack the precious pollen
and fertilize the flowers
It is her gift
and the culmination of millions of years
of co-evolution between wasp and tree
In perpetuating the relationship
she makes the ultimate sacrifice
The queen's figs have provided
for animals from ants to elephants
In traveling, they will disperse her seeds
No seeds will germinate
and somewhere in Africa
where a bat perched
or an elephant came to drink
there will grow a fig tree
In a few years it will sprout its first fig
and the scent from that secret garden
will touch a tiny wasp
which will turn upwind in search of the source
Once again, the two will come together
and continue the extraordinary relationship
that has provided for so many
over millions of years
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