Snippets of genetic material from dozens of insect species lie dormant in tea bags


Researchers at the University of Trier have developed a method for extracting and evaluating DNA traces of insects from dried plants. “We examined commercially available teas and herbs and found DNA from up to 400 different species of insects in a single tea bag,” says Henrik Krehenwinkel from the University of Trier, according to a press release. Together with colleagues, the biogeographer presented the newly developed method in the specialist journal “Biological Letters”.

When a bee collects nectar from a flower, it leaves some saliva behind. A bug stings a leaf, a spider leaves silken threads. All of this is sufficient to detect the DNA of the insects, explains Krehenwinkel. Eggs or excrement are also suitable traces for the biogeographer. Whether there is a limit to what can be detected still needs to be researched. “In principle, however, individual cells, such as those of a beetle, are probably sufficient,” says Krehenwinkel.

DNA from dried plant material

According to the University of Trier, the innovation of the newly developed process is that the environmental DNA (eDNA) is not taken from the surfaces of the plants as is usual, but from crushed, dried plant material. “Drying seems to preserve the DNA particularly well,” says Krehenwinkel.

So far, researchers have taken samples or caught the animals with traps when they investigated which insects are on which plants. In the process, the insects die; In addition, scientists miss out on a lot of information. This is because eDNA is usually not available for long on the plant cover because it is broken down by UV light or washed away by rain. Another limitation is that almost only insects sitting on the surface of the plant are recorded. “Now we can also prove which insects live inside the plant,” explains Krehenwinkel.



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