A beetle’s chemical warfare against marauding ants, birds and frogs has provided the inspiration for a European effort to design more efficient fire extinguishers, reliable pharmaceutical sprays and fuel-injection engines.The bombardier beetle’s toxic blasts of boiling-hot poison could even provide the impetus for mini rocket boosters to keep a spacecraft on the right trajectory, according to Andy McIntosh, a professor of thermodynamics and combustion theory at University of Leeds in the United Kingdom.
Found mainly in Africa and Asia, the bombardier beetle owes its unusual defense system to a chemical concoction that mixes in an abdominal chamber and then explodes out through a kind of release valve in a series of high-pressure, rapid-fire squirts aimed directly at attacking predators. One chemical, hydroquinone, combines with hydrogen peroxide to generate tremendous heat, as well as water and the noxious irritant benzoquinone — but only in the presence of specific catalysts secreted by cells in the beetle’s thick-walled combustion chamber.
In the beetle, the process is governed by “flash evaporation” directed by inlet and exit valves on its chamber. When open, the inlet valve allows hydroquinone and hydrogen peroxide to enter and begin mixing. The pressurized solution soon exceeds its boiling point, fueled by the heat of the chemical reaction. Once a critical pressure has been reached, the chamber’s exit valve pops open, instantly dropping the pressure and letting the water evaporate in the form of a rapid steam explosion. Ejection of the mix and closure of the exit valve let in more chemicals via the inlet valve and the process repeats.
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