When biologists move through meadows and forests to count insects, of course, they never get to see them all, of course. At most, they can get a close picture of the state of biodiversity in a given area. The "NZZ" reports on new and more efficient ways of monitoring biodiversity. Living beings constantly release genetic material in the form of hair, skin scales, mucus or feces to the environment. Scientists are also talking about "environmental DNA". Now several research teams have independently proven that environmental DNA can even be detected in air samples.

Huge task

"In view of the biodiversity crisis, we urgently need better information about the state and the spread of species," says Fabian Roger from ETH Zurich to the "NZZ". But this is usually an extremely time-consuming task, which also requires a great deal of expert knowledge in the field of taxonomy – especially in the case of the estimated 5.5 million insect species on Earth. The investigation of environmental DNA, on the other hand, is a faster and cheaper alternative. The genetic material of all species contained in the sample can be analyzed by means of so-called metabolic coding. A comparison with existing databases allows the identification of the species in the sample. The method has developed rapidly in recent years. But the investigation of air samples is comparatively little researched.

Great potential, but also uncertainties

This is what the ETH research group wants to change. In southern Sweden, they have therefore installed a vacuum cleaner-like device, which is normally used to check the air quality. The air is sucked in by water, where the DNA particles accumulate. The big advantage: No insects need to be captured and killed, as happens with traps. The researchers found about twice as many species in their air samples as they had collected "by hand". These included traces of insects as well as those of birds, mammals and pets. The method has potential. But as the "NZZ" writes, there are also doubts. Thus, the DNA in the air could be degraded rapidly by UV radiation and thus remain unrecognized. Or DNA traces could be transported through birds or their feces to foreign areas and lead scientists to false tracks.

Every effort to better and more reliable measurement of biodiversity is valuable. The factors that lead to an increase or a decrease in biodiversity need to be further investigated in order to ensure that biodiversity is maintained in the long term by means of efficient measures in the future.