BURST OF
BOMBORDIER BEETLE
PROF WAQAR
HUSSAIN
One day my son Zawar Hussain was
typing an article for me on the computer. Suddenly he felt burning under his
left foot along with a popping sound and he quickly lifted his foot and found a
beetle crawling on the carpet. He started feeling pain and irritation in foot. He
screamed in agony and we all rushed towards him. At that moment, he was holding
his foot in his hand and was murmuring in pain. We saw a “five-day moon” shaped
dark brown spot
on his foot and the attacker was lying half dead on the carpet.
He reported that this beetle has bombarded a missile of fire when he incidentally
placed foot on it. I washed the stain of burnt area with ethanol and the stain slightly
fainted and burning stopped. There was also a “five-day moon”
shaped mark of
dark brown colour on the carpet at the place of incidence. I tried to wash it
with alcohol but in vain.
Finding him well! We all started
examining the beetle by placing it on the white paper. When molested with straw,
the beetle squirted about a drop
of liquid which stained paper yellow,
indicating the toxin is of yellow colour. The beetle had a dark brown stiff
coating having patches of yellow colour. After 30 minutes the beetle died. In
the meanwhile, my children(Amsar Hussain, Zawar Hussain, Nisar Hussain and Sadaf Fatima) started questioning about the beetle’s habitat,
food, reason of attack, mechanism of attack,
chemistry of fire and toxin,
effect of spurt, cause of beetle’s illness and later on death, etc. All my
answers are stated below for benefit of the readers.
It is called bombardier beetle,
inhabitant of all continents except Antarctica. It is carnivorous and hunts for
other insects at night. It has more than 500 species with unique defense
mechanism. When disturbed, the beetle ejects a noxious chemical with
popping
sound in rapid burst from a gland present in abdomen. Beetle first produces and
then stores two chemical; hydroquinone
and hydrogen peroxide in separate
pouches present in rear tip of its abdomen. When threatened, the bombardier
beetle contracts muscles that force two compounds to flow through valve tube
into a thick walled “combustion chamber” lined with cells that secret catalases and
peroxidase enzymes. When two compounds combine, a violent exothermic
reaction takes place as enzymes decompose H2O2 into H2O
and atomic oxygen and also oxidise hydroquinone into para-quinone and atomic hydrogen. Keep in mind atomic oxygen or
atomic hydrogen is extremely reactive. The popping sound generates due to rapid
formation of gases that expand and rush towards area of low pressure as the
pressure of gases increase 1000 times so its principle is similar to that of other
explosives. The reactions also generate heat which escalate temperature to 1000C
(boiling point of water) and vaporize 20% of mixture (some water converts to
steam) which gushes out of the body due to escalated pressure. The vaporized
gases and steam exert pressure which closes the entry valve of combustion
chamber, thus protecting the internal organ of the beetle from venom produced.
The boiling, foul smelling liquid cum gaseous mixture is expelled through
outlet nozzle into the atmosphere with a loud popping sound. These hot gases
burn its enemy and the poison kills them. Astonishingly, the entire process of
pumping of compounds into combustion chamber, enzyme catalyzed reactions and
ejection of product takes place in 500th part of a second. It shoots
boiling liquid and gases 70 times in quick succession that can travel as far as
20 cm. Its attack is fatal for insects and painful to human skin. The ejection
barrel of beetle can swivel through 270o and can hit missile on the
face of insects. So, beetle can fire in multiple directions that too with immense
accuracy.
Hydroquinone is an organic compound
containing benzene ring and two hydroxyl groups at para position. It undergoes
oxidation to p-Quinone (poison for insects and toxic for man) which is then
ejected. Para-Quinone is bright yellow crystalline solid with pungent smell. It
stains skin dark brown and causes erythema (inflammation of skin in patches)
and leads to local tissue necrosis (death of tissues). It is also carcinogenic.
It can easily pass into the blood stream and depresses the bone marrow
production and can inhabit protease enzyme in cellular apoptosis (death of
cells). It is slightly soluble in water and soluble in acetone (nail polish
remover) and very soluble in ethanol (available in the West as alcohol and in
Pakistan as methylated spirit).
So, whenever someone is hit by chemically
loaded incendiary missile of bombardier beetle, one should clean the stain with
ethanol that will surely antidote the toxin of beetle and will also pacify the
burns.
Now the question arises, why attacker beetle
became ill and half dead after attack and latter on died? The answer is that
when it squirted, my son lifted his foot and in this struggle some pressure was
exerted on beetle and all its toxic material did not come out. And due to
pressure rear valve of combustion chamber slightly opened, thus some toxin
entered into its own body. Due to effect of toxin, it became half dead and
finally died proving the maxim, “The one who digs a pit will fall into it, and
whoever rolls a stone- it will come back on him.”
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