For years, scientists have been using water samples to trace plants, microbes, animals and fungi via the invisible bits of DNA they leave behind. Recently this eDNA technology has taken to the air, using spiderwebs to catch clues wafting on the breeze.
But scaling that up would be rough on spiders. And one web is not like another, making it a difficult medium. So scientists at the University of Waikato decided to test toy spiderwebs.
The team popped into a $2 shop for their high-tech supplies, sterilised the artificial webbing, then stretched it over coat hangers and hung the lot in a gazebo on a lifestyle block in Palmerston North. The place was bristling with life: farm animals, pests, native bush and farmland, even an aviary of exotic birds.
After five days, the scientists took the toy webs back to the lab (first, carefully removing the spiders that had turned up). They also took samples from a stream on the property and collected nearby natural webs for analysis, twirling the wild silk onto pipettes like candy floss.
Each medium—water, toy webs, and real ones—held a rich and diverse library of eDNA, and the fake webs had caught whispers of dozens of species missed by the others, including zebra finch, cow, chook, horsefly, tōtara, pinkgill mushroom, grey parrot, flax, sheep and clover.
“It’s surprising how much trace DNA there is in the environment,” says Angela McGaughran, one of the scientists. The fake webs could eventually be built more precisely and consistently, she says, and help trace species such as “birds, bats and non-aquatic insects” that water sampling can miss.
McGaughran has been to Antarctica multiple times for other research, and now wonders whether one day a trace of her will ping up on an eDNA test there.
