It shows that many insects still thrive in tea fields, meaning they are not heavily treated with pesticides.

German researchers have discovered traces of more than a thousand insect species, including spiders and mites, in dried tea and herbs from the supermarket. Your first reaction might be ‘yuck’! But please read on. According to researcher Henrik Krehenwinkel, the findings are encouraging. “It’s actually a good thing,” he says in an interview with Scientias.nl†

Traces of insects

The researchers took the study dried teas and dried herbs for sale in the supermarket – including chamomile, mint and parsley. They then analyzed these dried goods for the presence of so-called eDNA. “We are very interested in how insects interact with plants and what role insects play in an ecosystem,” Krehenwinkel explains. “This is very relevant to understanding insect decline. Analysis of eDNA makes research into this a lot easier. This is because, thanks to eDNA, we no longer have to look at the plant itself or count and collect insects.”

More about eDNA
In addition to the DNA that is in our cells, there is also something called environmental DNA (or eDNA for short). This is DNA that has escaped an organism and is roaming freely in the living environment of that organism. eDNA can be released in many different ways, for example through old, dead cells that release their contents, although any biological material could actually be a source of eDNA. In recent years, eDNA has already been found in water, snow and soil. In water in particular, this eDNA is already being used to determine which species occur where and the state of certain fish populations. In addition, not so long ago, researchers have shown that they can also pick eDNA from the air in order to identify the animals in the vicinity.

In short, every organism leaves traces of its DNA in its environment. Researchers can then sequence this eDNA, allowing them to characterize biological communities without actually collecting specimens. Now researchers have found a new method to use, for example, a jar of dried chamomile in the supermarket to find out which insects were on the plant when it was still growing on the tea field.

Thousand species

And it turns out there are quite a few. “We have discovered several arthropods in several commercially produced teas and herbs,” the researchers wrote in their study. “Over a thousand species in all.”

Disturbing

Disturbing? “No, not really,” Krehenwinkel says when asked. “It’s not like drinking bug powder after you’ve made a cup of tea. It largely concerns eDNA, i.e. minuscule remains of an insect, for example from a chewing spot on a leaf.” However, the enormous number of insects that the researchers found is surprising. “What surprised me most was the great diversity of arthropods in the tea bags,” Krehenwinkel continues. “We found the DNA of up to 400 different insect species in a single tea bag. This can be explained by the fact that the tea you buy in the store is often a mixture of plants from tea fields from different parts of the world.”

“We found the DNA of up to 400 different insect species in a single tea bag”

Encouraging

Although you may be a bit shocked by so many insect tracks that are probably also in your kitchen cupboard, the finding that this eDNA comes from so many different species is actually encouraged, Krehenwinkel emphasizes. “It means the tea fields are home to a very large diversity of arthropods,” he says. “In addition, it shows that the fields are not heavily treated with pesticides. So it’s actually a good thing to have some insect eDNA in your teacup.”

Unavoidable

Incidentally, there is a good chance that you, in addition to the dried tea and herbs in your kitchen cupboard, have already eaten a lot of insects. That’s because all processed foods—such as applesauce, orange juice, peanut butter, chocolate, bread, and coffee—contain insects. In the production of these foods, it may well be that there are some apples that have just crawled into a fruit fly. And that’s how finely ground insects end up in the apple juice and applesauce. The same goes for tomatoes and ketchup, for grain and flour for bread, and for coffee beans and coffee. It has been calculated that, without our knowledge, we get up to about 500 grams of insects per year.

According to Krehenwinkel, it is also unavoidable that some insects end up in the tea when the plant is harvested. “But a lot of the DNA is probably eDNA,” he reassures shivers. “To get rid of it, you can treat it with heat. But I even think that boiling water for tea destroys a lot of DNA.”

trace

According to the researchers, their newly developed technique is not only useful for analyzing dried goods from the supermarket. “Our approach can also be used to trace the origin of illegal plant material that has been confiscated by customs or to trace agricultural pests,” Krehenwinkel sums up. The team therefore shows that eDNA analysis has great potential, in addition to being a promising method for studying biodiversity.

All in all, the researchers show with their study that it is actually not so bad if there are also traces of insects floating around in your freshly brewed and steaming cup of tea. It means that the insect populations in the tea fields are still thriving today, despite the worldwide insect deaths. Think about that the next time you take a sip.