The bombardier beetle, while small, has been found to be a quite powerful insect.
According to Christian Science Monitor, when threatened, the insect shoots a superheated chemical spray. This spray causes a minor discomfort for unsuspecting humans, but is almost certain death for other insects, such as attacking ants. The bombardier beetle’s defensive spray is a product of near-instantaneous chemical explosions from within the body that had, until now, only been observed externally. However, with the help of x-ray imaging, researchers were finally able to study this incredible mechanism in real time. This study was published in Science, explains how the bombardier beetle’s defensive glands produce and endure these consecutive explosions.
The bombardier beetle, with some 1,400 known species on nearly every continent, average less than an inch in length. Bombardier beetles belong to the subfamily Brachininae because for their unique properties, which means they produce hotter and faster toxic sprays than their close relatives. The powerful defense of B. elongatulus works a little bit like a chemical heat pack. A pair of glands, each with two compartments, contain the ingredients for the spray. One compartment is a flexible sac that contains hydrogen peroxide, water, and chemical compounds called hydroquinones. The other compartment is much stiffer and contains enzymatic peroxidase. A valve divides the two chambers, preventing their contents from mixing together.
However, when a beetle becomes threatened, it contracts the muscles surrounding the reservoir, allowing reactive solution into the enzyme chamber. This triggers an exothermic reaction that heats the mixture to about 100 degrees Celsius, boiling off a third of the water and spewing out toxic vapor in the process. Through synchrotron X-ray imaging, researchers were able to watch this process occur within the bodies of these insects. To their surprise, they saw the vapor expand outside the extent of the glands. This meant that the reaction chamber was actually very flexible. As this region expands, it closes off the valve, thus automatically stopping the flow of toxic vapor. When it deflates, the valve opens again and produce a fresh blast. The bombardier beetle’s highly efficient defense could find support in biomimetics, which is the imitation of natural models to solve human problems. This could even be used to create things such as better fuel injectors for combustion engines.