Researchers discovered 400 species of insects in tea bags

For example, when a bee flies to a flower to pollinate it, it leaves behind some saliva. An insect stings a leaf, a spider leaves silk threads. All this is enough to detect the insects’ DNA, says junior professor Henrik Krehenwinkel of the German University of Trier. Suitable traces are also eggs or feces. It must first be investigated whether there is a limit from the moment that something is no longer demonstrable. “In principle, however, individual cells, such as those of a beetle, are probably sufficient.”

The process, which Krehenwinkel developed together with Sven Weber and Susan Kennedy, does not, as is usually the case, extract the environmental DNA (eDNA) from the surfaces of the plants, but from ground, dried plant material. “Drying seems to preserve the DNA particularly well,” says Krehenwinkel. The eDNA is not available for long on the plant cover because it is broken down by UV light or washed away by rain. In addition, insects would be considered more on the surface of the plant. With the new method, the researchers can now also show which insects live in the plant.

Historical comparisons possible
According to Krehenwinkel, this opens up the possibility of analyzing old plant stocks, for example from museums, and comparing their colonization with today’s. “In this way, it would be possible to find out what the insect community looked like years ago when the plant was collected and what it looks like on the site today.” This is important in view of insect mortality.