DNA from hundreds of insect species can be found in your cup of tea, according to new research.
Researchers can use tiny traces of DNA to track trends over time, such as population declines and which insects interacted with the plants before harvesting and packaging, according to a recent study published in Biology Letters.
It may include bees that pollinate the plants, caterpillars that build cocoons on them, or spiders that spin webs around them.
There’s very, very specific interactions and very cryptic interactions that we know very little about, and this is something that has not been studied before, Henrik Krehenwinkel, The lead author of the study and an ecological geneticist at Trier University in Germany, told the Smithsonian Magazine.
Dr. Krehenwinkel and his colleagues found that dried plant material is a promising source for environmental DNA analysis, which has become a popular research technique in the field of biomonitoring in recent years. Water, soil, and plant surfaces have been sampled by researchers. The researchers chose teas and herbs for this study since dried leaves can leave DNA traces when crushed and dried.
“If you take a sample of coffee, which has been heavily processed, you probably have very little DNA left,” Krehenwinkel said. “Then we tried things that were as natural as possible.”
It took the team four continents to buy teas and herbs at grocery stores, he told the magazine. They purchased multiple versions of the same product from different brands in order to test the quality of products from various origins.
The team then developed a method for extracting the arthropod DNA from the plant materials and amplifying it. Most of the DNA in tea leaves comes from the tea plant, but a small amount comes from insects.
“Probably 99.999 percent of the DNA we extract is plant DNA, and only a very small percentage is insect DNA,” Krehenwinkel said. this, of course, is good news for tea drinkers who want to drink tea, not insects.”
The research team analyzed various commercially produced teas and herbs such as chamomile, mint, and parsley.The samples contained DNA belonging to more than 1,200 different species belonging to more than 20 different orders of insects. They found on average more than 200 different types of insects per tea sample.
They were in general, in agreement with the known distributions of plants and arthropods. For instance, mint tea contained DNA from insects native to the Pacific Northwest, and green tea contained DNA from insects found in East Asia.
This technique could be applied to any dried plant, the researchers wrote, and would be valuable for monitoring endangered insect species and tracking crop pests.
Krehenwinkel is also interested in extracting insect DNA from dried plants that were collected decades ago and stored in museum collections, which could be compared to modern plants to track how species have changed, the magazine reported. This could potentially help with insect conservation efforts as well.
The new method could let researchers “travel back in time and see how communities have changed,” he said.