Spiders, Prey Leave DNA

A study of black widow spiders suggests that the arachnids leave traces of their own genetic material and DNA from prey in their sticky webs.

Bob Grant
Bob Grant
Nov 30, 2015

WIKIMEDIA, BROCKEN INAGLORYResearchers have developed a method for noninvasively sampling DNA from spiders and their prey items simply by harvesting genetic material left on the arachnids’ sticky webs. Scientists who studied captive black widow spiders (Latrodectus spp.) at an Indiana zoo reported their results last week (November 25) in PLOS One. “In the past, identification of spiders has relied on morphology, especially looking at the genitalia of spiders because they’re very different between different species of spider,” study coauthor Charles Xu, a graduate student at the Erasmus Mundus Master Program in Evolutionary Biology in Europe, told BBC News. “But there are a lot of errors associated with these kinds of methods, and now with the advent of new genetic technologies we can more accurately identify these species.”

Xu and his colleagues found that they could extract spider mitochondrial DNA and genetic material from the spiders’ prey, house crickets, up to 88 days after living organisms had been present on the web. This method of noninvasive DNA fingerprinting, “next generation meta-barcoding sequencing,” may yield other applications to aid in conservation efforts, pest management, and ecological studies. “These genetic technologies can be a lot more sensitive than traditional sampling methods and enable us to detect DNA of any spider or insect without having to specify which species we’re looking for in the first place,” Xu told Live Science. “They could allow earlier detection of [endangered or invasive] species. For endangered organisms, it could be important for marking off new conservation areas, or for invasive species, redrawing the invasive range.”