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Explorations of our lively planet can now extend down into a world of the infinitely
small.
With new instruments, new techniques, and new ideas, we can re-scan familiar and unfamiliar
life forms.
Through our new eyes, we enter an alien environment.
Here, the struggle for existence is no cliché.
It means possessing ways to ward off attack.
Weapons that can, at a moment's notice, spring to the defense of a life.
The setting, Arizona, summer 1982.
The explorer, Professor Tom Eisner.
His passion, the secret world of insects, and the hidden weapons they use in defense.
Insects, it's been said, will inherit the earth.
A larva can instantly burp up its droplet of resin, and the repellent takes effect.
The smell drives off the ant, and if it gets glue on its legs, it may get permanently entangled.
The droplet is eased out, but danger over is sucked in again and held for later use.
Few of us realize how many plants are protected by their own chemicals.
The milkweed is no exception.
It squirts out its poison when injured, but again, some insects are undeterred.
Some caterpillars, including those of the monarch butterfly, even accumulate the chemicals
in their bodies and retain them as they grow and develop.
So as adult butterflies, they themselves are laden with the poisons, beneficiaries of what
they gained in their youth.
Many insects use the same strategy.
If an insect has evolved a way of being insensitive to a plant's poisons, then why not use these
poisons in its own defense against others?
Eisner and his colleagues have made a detailed study of one moth that lives on a poisonous
legume, and the research turned out to have an unexpected twist.
The moth is called Utathisa.
We first noticed that the caterpillars of Utathisa competed for the seeds of the plant.
That's where the poisons are concentrated, and they're very potent.
Chemically they're a type of alkaloid, bitter and highly toxic to us.
The caterpillar chews its way into the pod and eats the whole seed.
When the larvae are crowded on the plant, they may be winners and losers in this competition.
Those best able to break into the pod may end up with the most poisonous alkaloid in
their bodies, and as an adult, the moth retains them.
Unlike many other moths that remain hidden by day, Utathisa risks exposure.
The poisonous alkaloids are its defense, the coloration its warning.
Red, white and yellow make it extremely conspicuous.
Bright and attractive, it lives in a world full of many dangers.
Utathisa has problems with spiders.
If it flies into an orb of a spider, it might be eaten.
It may have problems with bats, and of course, it may have problems with birds.
Birds are among the major enemies of Utathisa.
They feed on many insects, and these scrub jays in particular are aggressive toward insects
that come within sight.
Eisner tested the moth's palatability.
He offered the scrub jays edible and inedible insects.
First, a tasty moth.
It's eaten with relish.
Now the jay is given a choice, edible insects in the palm and an Utathisa between thumb
and forefinger.
All but Utathisa are taken.
The warningly colored moth is undoubtedly seen but ignored.
It will survive another day.
The gourmet jay remains selective and only accepts the best.
Another edible moth is grabbed and eaten piecemeal.
Pulling the wings out, they often do that.
Wings of us just scales on paper essentially.
It's like taking the wrapper off a candy bar.
The head, thorax, and body, that was the good part.
Now you liked that, didn't you?
Utathisa continues to be ignored whether offered by itself or in combination with edible insects.
It survives an occasional peck but is obviously well protected.
The research didn't end here.
It developed to reveal that in the courtship of the moths, the poisonous alkaloids have
another intriguing role to play.
For all his work on the moth's defense, he had to breed them in great numbers.
When in their separate boxes, both male and females are relatively inactive.
But once united in an artificial nuptial chamber, they perform a courting dance quite naturally.
With his frantic fluttering, it's hard to see what the male does.
The dance that the male performs around the female is too quick to really follow with
the naked eye, so we resort to photography, flash photography, which catches events in
a nice frozen fraction.
And it was by means of this flash photography that we eventually learned exactly what goes
on when these two are interactive.
Eisner took dozens of photos, always trying to catch the male when closest to the female.
Some pictures were timed just right and gave him the answer.
During the flutter, the male opens up his abdominal tip and exposes a hidden structure.
This he brushes against the female.
The microscope revealed that he has two brushes for that purpose, splayed at the moment of
contact.
And every bristle of the brush is coated with a secretion.
It's at once an aphrodisiac and the carrier of a very special message.
By greatly increasing the magnification, he was able to find exactly where the secretion
was coming from.
It was oozing out between the sculpturing on the surface from tiny pores.
I asked some friends who are chemists to analyze the secretion, and they found it was derived
from the poisonous alkaloid eaten by the caterpillar.
This set us thinking.
We speculated that the amount of defensive chemical the male caterpillar stores will,
in due course, be measured by the female moth by judging how potent his aphrodisiac is.
The males were raised on an artificial diet with no alkaloid.
They grew up into normal-looking adults, but they had no defensive chemical, so no aphrodisiac
either.
The next step was to see whether the female responded in a different way to males with
the aphrodisiac and those without.
The female is presented with both.
She initiates courtship.
She climbs up a plant and emits her sexual attractant, which drifts downwind.
A male flies in and begins his fluttering dance.
Not surprisingly, the tests showed that the female preferred males with the aphrodisiac.
She was more likely to mate with them.
They were also best protected chemically.
Eisner believes that females favor males which are the best at storing poisonous alkaloid.
This ability might be inherited, so it will also benefit their offspring.
Their caterpillars will be better alkaloid gatherers and have a better chance of survival.
At night, our eyes are blind to most natural dramas played out on the woodland floor, but
there are some insects that flash out their own picture of life and death in a visual
morse code.
The signals speak not only of courtship but deceit and reveal a new dimension in the use
of chemicals in defense.
I've just collected a net full of fireflies.
Fireflies are the one insect that one can see at night.
It's an insect that every American child knows.
The males and the females are active at night trying to find one another.
The ones I've collected are all males.
They're flashing and they ordinarily flash when they fly because in fact they're announcing
their presence to the females.
The females sit waiting on a plant and answer the males with a welcoming flash.
It's a courtship duet in lights.
The male responds to a reply and flies down to mate.
Each species of firefly has its own individual code of flashes.
A female identifies her own male by the rhythm and number of flashes.
Then she answers after a specific time.
Few mistakes are made and compatible partnerships are forged.
The code of the visual duet is precise and ensures that the mating encounters are of
the right kind.
But encounters of the wrong kind do occur.
There are fireflies, female fireflies, that deliberately set out to break the code.
During the courtship they attract their own males for mating from the many signaling above.
But these same females can deceive the males of other species by imitating their females.
They mimic another's courtship flash and lure down a stranger, but not for mating.
She is a femme fatale and the male has been enticed to his death.
For a female about to lay eggs, prey caught so easily is certainly a boon.
But this elaborate counterfeit is not just to obtain food.
There's an additional bonus.
It was discovered that the males she eats are full of defensive chemicals, this time
poisonous steroids.
The femme fatale has no steroids of her own.
She's defenseless.
Her skill is to acquire them in this ingenious way.
She builds the male steroids into her own body.
Now she too is poisonous and protected.
She's most vulnerable when searching for a place to lay her eggs.
A wolf spider waits in ambush.
Touched and tasted, the female firefly is rejected, saved by her newly acquired steroids.
They seem to leave a nasty taste, but neither spider nor firefly is permanently harmed.
There are times and places when working at night, we would welcome having our own built-in
chemical defense against midges and mosquitoes.
We rely on creams and lotions and a wary eye on the bigger beasts that bite.
Of all the insects that are chemically protected, there's no doubt which takes the prize.
The bombardier beetle.
Its weaponry a salvo of artillery.
It's a high-tech beetle without parallel in the animal kingdom.
No insect has been so much sheer fun to work with as the bombardier beetle.
Just watching how it fends off an attack is spectacular.
You can actually see it fire and hear the shot.
It's long been known that these beetles spray poisonous quinones.
They fire them from their abdominal tip with a crack and a puff of smoke.
Bombardiers have a well-stocked armory.
If under constant attack, they can fire more than 20 times and they're amazingly quick
at it.
Their escape is immediate, leaving the spider with a mouthful of quinone.
It wipes its body on the ground.
Then it frantically cleans its mouth parts.
Toads too hunt at night.
They gulp their food, striking and swallowing at one fell swoop.
The bombardier's fast retort stops the toad in mid-action.
The crack, the puff of smoke and the instant action all point to a very sophisticated form
of defense.
What is it that the toad feels on its tongue?
Is it just an irritation, some sort of chemical soreness?
Eisner put the question to the test.
I popped a bombardier beetle in my mouth and could sympathize with the toads.
It was an acrid taste, but also an immediate peppery burning sensation.
And the beetle seemed to be such a phenomenal marksman.
Even small ants were always hit.
We simply had to take this animal into the laboratory for a closer look.
One of the really amazing things about this animal is its ability to spray in a very beautifully
aimed fashion.
And that shows up very nicely when you put the animal on indicator paper.
What I'm going to do now is I'm going to pinch very lightly one leg after the other, just
as if I were an ant biting these legs.
I'm going to start with the right hind leg.
Right front leg.
Left front leg.
In fact, in nature, a beetle would actually be able to walk away through a swarm of ants
after having discharged only once.
He's performed.
I'm going to take him off the wax, which is very easy to do, and put him back.
Oops.
Well, you probably heard that.
He just fired.
I felt it because the spray is hot.
Bombardier beetles, when they spray, are really producing a chemical explosion, which not
only produces sound, but also produce heat.
Now if one wants to measure that temperature, one cannot use a conventional thermometer
because the explosions are very short, only a few thousands of a second.
You need a special thermometer, an electronic thermometer, which responds very quickly to
a very short production of heat.
Now let me just move the beetle back ever so slightly.
Okay.
The thermometer is on.
And there we go.
10, 20, 50.
It's about 90, 95 degrees.
And those are centigrade degrees.
It's scalding hot.
We've actually been recording the sound that the beetle produces.
There's a microphone in the back of the tube that picks up the sound, and there's a tape
recorder on which we've recorded the sound.
Now one of the remarkable things is that there's information in that sound.
We can find out about that information if we slow the sound down.
We can do that.
We can watch the sound on the oscilloscope at the same time that we listen to the slowed
down version.
The oscilloscope shows clearly that the spray is pulsed.
The next step is to see it.
They set up a camera to film it in slow motion.
I'll give you the word on camera.
Let me get close to that leg first.
Not quite yet.
Go.
At 400 frames per second, the action has been slowed down, but not enough to see the individual
pulses.
So they went to a lab and filmed the beetle at an even faster speed, at an incredible
4,000 frames a second.
Oh, that.
There were the pulses, each one corresponding to the individual bursts of sound.
And that wasn't the end of the story.
They were intrigued by the mechanism of a weapon that could pulse explosions.
Inside the rear of the beetle, there's a pair of glands, each with a large chamber containing
hydroquinones and hydrogen peroxide.
When the beetle fires, the chamber is compressed, forcing the compounds into a small reaction
chamber, where enzymes set off an explosion, creating hotquinones, which then shoot out.
Explosions are repeated one after the other, each forming a separate pulse of spray.
The beetle makes explosions in sequence because the reaction chamber is too small to handle
more than a little explosive at a time.
A big reaction chamber could handle more explosive, but the heat produced would make things too
hot for the beetle itself.
Nature is indeed incredible.
Among the spiders, there's a bombardier disposal squad.
The orb weavers can just about cope with this explosive beetle.
A bombardier rarely shoots when handled with care.
Flying into a web doesn't provoke it to fire, nor does it react when spun into a cocoon
of silk.
By the time it does shoot, it's too late.
The swathing of silk muffles the explosion, and the spider is only stunned.
The beetle's shroud is wound more thickly, and though it continues to fire, its fate is
sealed.
There's no escape.
Here is a challenge to what seemed an infallible defense.
All these insects and their allies are in effect exploiting nature's chemistry set,
making full use of the same fun and games that mischievous children might in making
their first stink bombs.
But among the many millions of insects, the game is hugely varied and played for real.
This is an arms race between predator and prey, which we have scarcely started to explore.
The scenes at the end of our film showing the bombardier beetle and the spider were
actually shot on the last day of filming near Portal, Arizona.
That was the end of the film, but it wasn't the end of the day's excitement.
After dinner that evening, Tom Eisner decided to take one last look around before turning
in.
Cameraman Roger Jackman went with him.
And standing near a small pond, Roger thought he saw something quite remarkable.
He called to Tom, and together they observed the following strange sight.
Thousands of spadefoot toads just emerged from the tadpole stage were climbing out of
the water and sitting on the muddy shores of the pond.
They were all very small, just under an inch in length.
Suddenly Jackman saw one of them almost disappear into the mud.
Jackman and Eisner then noticed that many of the toads had been pulled down into the
mud with only their heads sticking out.
Others were dead or dying.
When Tom and Roger tried to pull a toad out of the mud, they felt a strong resisting force.
Assessing that some unseen predator lurked beneath the surface, they dug into the mud
but found nothing.
Whatever it was seemed capable of quick evasive burrowing.
Eventually, Tom Eisner decided to take a sample of the mud back to his laboratory for testing.
There he found a large grub-like insect larva, the early stage of a type of horsefly.
About as long as the toads, the larva, as Eisner discovered, can grab any toad that
settles above it with its hook-like mandibles and pull it beneath the surface.
There it drains the poor toad of its blood and body fluids.
Tom Eisner and Roger Jackman published their findings.
It was the very first time this natural phenomenon had been recorded in a scientific journal.
For those of us who work on nature, it's rewarding to know that sometimes the production of our
films results in a new scientific discovery by our colleagues.
I'm George Page for Nature.
Nature is made possible by public television stations, your gas company, and America's
gas industry, developing new sources of gas energy and ways to use gas more efficiently
for more than 160 million people across America.
Next week, we go to India, to the Bharatpur National Park, in one unusual year when the
monsoon rains fail to arrive.
The Missing Monsoon, our film next week on nature.