The genetic ghosts of over 1,000 bugs have been detected from samples of tea, indicating there’s rich “diversi-tea” in your morning cuppa. The scientists behind that particular pun coined it after discovering that eDNA suggests there’s a lot more than zesty notes and caffeine to be found in the delicious dried plant matter.
While brewing bugs might not sound terribly appealing to some, the finding isn’t to say that you should be looking for spider legs in your oolong (disclaimer: we can’t guarantee you won’t ever find a spider in your tea) but instead represents an alternative approach for evaluating species richness in an ecosystem.
The study, published in the journal Biology Letters, looked for the presence of environmental DNA (eDNA) in dried tea leaves and herbs bought from food stores in Germany. eDNA samples are a bit like genetic breadcrumbs left behind by living things and they can be enriched and sequenced as a way of working backwards to establish what species are living in certain environments.
Science has searched for eDNA in wet and dry environments, but this study was unique in looking for signs of life preserved on dried samples of plant matter. Brewing tea involves infusing dried up plant products in hot water, so drinks like chamomile and green tea could all be analyzed in this way.
“Altogether, we recovered 3,264 arthropods [taxonomic units] representing 3 classes, 22 orders, 281 families, 1,068 genera and 1,279 species, comprising herbivores, predators, parasitoids, and detritivores,” wrote the authors.
“Each separate sample recovered more than 200 [taxonomic units] on average, with green tea showing the highest mean [variety of bug eDNA].”
While the genetic residue of a thousand bugs might not be the earthy notes you were hoping for, the discovery could prove to be very useful for future research into arthropod biodiversity and conservation, as well as monitoring pests and plant imports.
“Atypically for eDNA, arthropod DNA in dried plants shows a very high temporal stability, opening up plant archives as a source for historical arthropod eDNA,” say the authors.
“Considering these results, dried plant material appears excellently suited as a novel tool to monitor arthropods and arthropod–plant interactions, detect agricultural pests, and identify the geographical origin of imported plant material."
Dried plant matter as a monitoring tool also comes with the benefit of being easy to collect, dry out and store meaning rich libraries of non-perishable arthropod biodiversity archives can be established with relative ease. We’ll drink to that.