Spiders may build their webs to catch prey, but trials in Slovenian forests have shown they can also moonlight as a way for humans to monitor the biodiversity of ecosystems.
Recent years have seen a growing interest in detecting species by collecting the fragments of DNA they shed in an environment, an approach that is often less invasive and quicker than traditional surveying with nets, trays and other equipment.
Matja啪 Gregori膷 at the Slovenian Academy of Sciences and Arts turned to an unusual tool to collect such environmental DNA: the orb webs of garden spiders (Araneus diadematus) and sheet webs of common hammock-weaving spiders (Linyphia triangularis).
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The webs act as a passive filter for the air, capturing DNA from insects, fungi and bacteria 鈥� and providing an elegant alternative to the air filtering machines ecologists use, which need to be powered by heavy generators.
鈥淭he results are fantastic, much more than I hoped for. From 25 webs, I found [DNA from] 50 families of animals, from nematodes to butterflies, moths, wasps, bees, beetles and flies, everything. The richness of information surprised us a lot,鈥� says Gregori膷.
He and his colleagues got the idea from in the highly controlled environment of a zoo, but Gregori膷 says their research is the first proof of concept in the wild. The approach could complement traditional ways of surveying pollinators, which are suffering major declines, or be used for the early detection of pests and invasive species.
The use of environmental DNA to monitor ecosystems is growing, with the technique being deployed by regulators in English rivers and lakes. The approach doesn鈥檛 require years of taxonomical knowledge to identify species, which instead have their DNA matched against databases. 鈥淵ou don鈥檛 have to be a spider expert to use spider webs,鈥� says Gregori膷.
Gregori膷 sees webs and environmental DNA as complementary to, rather than a replacement for, traditional methods. But he says: 鈥淲e shouldn鈥檛 shy away from exploring new methods to answer old questions.鈥�
Reference:听bioRxiv, DOI:
