Scientists have discovered that spider webs provide DNA information about insects in forests. The information enables scientists to monitor the biodiversity of ecosystems.

Matjaž Gregorič at the Slovenian Academy of Sciences and Arts, and his colleagues, conducted a study on spider webs in 2020. 

They used the webs of two species of spiders: (1) Garden Spiders (Araneus diadematus) that make orb webs, and (2) Common Hammock-Weaving Spiders (Linyphia triangularis) that make cup-shaped webs. 

The spider webs act like a filter, trapping air particles, which also contain DNA from insects, fungi, and other bacteria. 

Matjaž Gregorič said that in 25 webs, he found DNA from 50 families of animals, from nematodes to butterflies, moths, wasps, bees, beetles, and flies. He said, ‘the richness of information surprised us a lot.’

The researchers got the idea from a 2015 trial in a zoo environment, but wanted to test the same approach in the wild. The approach complements the traditional ways of surveying insects to detect pests and invasive insect species.

The use of DNA to monitor ecosystems is growing. The technique has been used in England. Matjaž Gregorič said that using spider webs does not require scientists to have taxonomical knowledge to identify species, because the DNA can be matched against information databases. ‘You don’t have to be a spider expert to use spider webs,’ Matjaž Gregorič said.

He said that his method does not replace traditional scientific methods. Instead, it complements and reinforces other methods, and is a new way of exploring information. 

Reference: bioRxiv, DOI: 10.1101/2020.07.18.209999v1

Photographer: Martina Nicolls

Martina Nicolls: SIMILAR BUT DIFFERENT IN THE ANIMAL KINGDOM