Spiderwebs emerge as a low-cost tool for wildlife DNA surveillance

Environmental DNA, or eDNA, refers to genetic material that organisms release into their surroundings. Over the past decade, biologists have used sequencing technology to analyze eDNA from soil, water, air, and animal droppings to monitor endangered species and detect invasive species. Spiderwebs, because they are sticky, naturally capture bio-detritus such as saliva and pollen from plants and animals, making them “probably one of the best substrates” tested so far, according to Joshua Newton, a molecular ecologist at Curtin University in Perth, Australia.

Newton compared spiderwebs with vegetation swabs, water, soil, and a fan equipped with a filter near a zoo and wildlife sanctuary outside Perth. Vegetation swabs revealed more forest mammals and water samples identified more fish, but no passive tool matched spiderwebs’ ability to identify vertebrates. The results echoed a similar study in France. However, the team had to destroy about 40 webs to collect data. “It kind of goes against everything that we’re trying to do if we’re collecting the home of an organism,” Newton said.

Angela McGaughran, a genomicist at New Zealand’s University of Waikato, saw Newton’s research and decided to test synthetic webs. She bought a bag of fake cobwebs from a Halloween store, wrapped them around coat hangers, and hung them outside. The artificial material captured eDNA from cows, sheep, and exotic birds in a nearby aviary. It also detected fungal spores better than real spiderwebs, which could help plant pathologists watching for agricultural threats. Her group is now planning larger experiments to determine whether artificial webs offer a cost-effective and efficient way to copy spiderwebs’ DNA-snagging ability anywhere.