Beetle that shoots acid from its rear: How the bombardier beetle’s explosive defence works

The bombardier beetle is famous for having an unusual defence mechanism, which can be referred to as squirting acid from the back end. This defence mechanism is possible because of the quick reaction that occurs inside the insect and creates heat and pressure, enabling the beetle to create a hot and irritating fluid to ward off any attacking species.This species of beetle has become very popular among scientists because of its effective use of defence mechanisms. It is important to note that, unlike the passive defence strategies, this organism actively develops its strategy when it senses any threat. This bombardier beetle insect is among a family of ground beetles which sprays a burning liquid when threatened by ants, spiders, and other predatory animals. This insect produces a defensive liquid containing irritant substances like benzoquinones that cause severe pain and harm to would-be predators. The reaction is quite intense as it reaches a high temperature of nearly 100 degrees centigrade in rapid bursts. It is because of its defence mechanism involving temperature, toxicity, and controlled discharges that makes this beetle unique compared to most insects.The bombardier beetle relies on a carefully controlled chemical reaction mechanism in order to defend itself, producing an explosion of heat, gases, and harmful chemicals. In the abdomen of the beetle, there are two storage chambers for the hydrogen peroxide and hydroquinones. Upon sensing any danger, the beetle releases these chemicals into a chamber containing some other chemicals, including enzymes like catalase and peroxidase. When these enzymes interact with other chemicals, heat, gases, and defensive chemicals are produced.According to the scientific research, “Molecular basis of the explosive defence response in the bombardier beetle Brachinus crepitans,” published in The Royal Society, there are certain enzymes and proteins responsible for controlling the timing and amount of these reactions, resulting in a highly controlled reaction mechanism.The beetle can produce high-temperature reactions without injuring itself, thanks to its internal structure and mechanisms of control.Nitrogen and hydroquinone are stored separately and then mixed in the beetle's reaction chamber. The walls of the reaction chamber are designed to face the heat and pressure generated during the explosive reaction, therefore protecting the insides of the beetle from injury.A recent study, “Bombardier beetles repel invasive bullfrogs”, published in the journal PeerJ, explains how the structural adaptations and controlled mechanisms of release of the beetle allow it to create multiple explosive reactions without injuring itself.The pulsed releases of the hydroquinone-nitrogen reaction also prevent overheating, allowing the beetle to maintain its efficiency when creating multiple explosions.The special defence system used by the bombardier beetles will provide insight into other areas in science, such as chemistry, biomechanics, and evolution.It shows that natural systems can effectively manage fast reactions, which can potentially be used for mechanical engineering purposes involving the release of pressure and heat.The fact that bombardier beetles can produce explosive reactions, store toxic substances, and expel these when necessary proves the advanced nature of evolution within species.