The beetle that hears fire: why it is so valuable for science

The black pine jewel beetle flies deliberately towards forest fires. What sounds paradoxical at first helps the ecosystem recover and inspires new technologies for early fire detection. For weeks now, severe wildfires have been raging across large parts of Europe. Entire regions have to be evacuated, people are losing their homes and lives are repeatedly lost. The persistent heat is making the situation even worse. According to many researchers, climate change is increasing both the frequency and intensity of wildfires. But scientists are looking at much more than just how fires can be extinguished. They are also studying what happens afterwards and which solutions nature itself offers. Playing a key role here is a rather inconspicuous inhabitant of our forests: the black fire beetle. A beetle that seeks out fire The black fire beetle (Melanophila acuminata) is one of the few animals that specifically respond to forest fires. As soon as a blaze has burned out, it flies to the scorched areas to lay its eggs there. Lydia Schübel, a biologist and head of animal welfare inspection at the Munich Animal Welfare Association, explains to Euronews why. "The beetle flies towards the flames because its larvae can only develop in freshly burned trees. Healthy trees have defence mechanisms that the small white larvae cannot overcome." What is remarkable, Schübel says, is that the insects are able to detect a fire "at least 80 km away". Exactly how the beetle finds fires has fascinated researchers for decades. Scientists at the University of Bonn have now shown that the insect can literally "hear" fire. On either side of its body the beetle has special sensory organs. They consist of tiny cavities filled with fluid. When the heat radiation from a fire hits these structures, the fluid expands and distorts delicate sensory hairs. The nervous system registers these pressure changes in much the same way as sound waves. A model for new fire detectors It is precisely this mechanism that is expected to help people in future. Since the early 2000s, researchers at the University of Bonn have been working to reproduce the beetle's sensory organ in technical form. The field of research is known as bionics, in which solutions found in nature are transferred to technical applications. The scientists have developed a simple infrared sensor modelled on the beetle. Instead of the natural sensory organ, it uses a thin plastic plate which expands very slightly when exposed to thermal radiation and passes this movement on to a sensor. Project leader Helmut Schmitz explained in a report on the project's progress that wildfires in the European Union alone cause damage worth billions. Detecting them as early as possible could help prevent devastating major fires. In the long term, bionic infrared sensors could therefore contribute to early fire detection. According to the researchers, the first prototypes cost only a few euros and were thus significantly cheaper than conventional infrared sensors. Although they initially did not match the performance of existing devices, the team regards them as a highly promising approach. After the fire, the forest starts all over again But many people are also concerned with what happens after a fire. The black fire beetle is one of the so-called pyrophilic species, animals that benefit from fire. Its larvae tunnel through the dead wood and in doing so speed up its decomposition. According to Lydia Schübel, this means nutrients return more quickly to the forest soil. The loose dead wood at the same time creates favourable conditions for new plants. The black fire beetle is not alone in this. "Other pyrophilic animal species in Germany include the four-spot runner beetle, the pit ground beetle, the pine bark bug and the smoke fly," Schübel tells Euronews. Worldwide they are regarded as important helpers in the regeneration of forests. Some plants are also adapted to fire, Schübel adds. Some have particularly fire-resistant traits, while others only open their seed pods after intense heat, helping forests to grow back quickly. Even certain bird species benefit for a time from the changed habitats. Species such as Eurasian wryneck, tree pipit and common redstart use the dead trees as nesting sites and find food particularly easily in the open areas. Wildfires remain natural disasters with mostly devastating consequences. At the same time, however, they also show how resilient ecosystems can be and how much there is to learn from nature. Paradoxically, a beetle that actively seeks out fire could in future help to detect blazes earlier and limit their impact.