Spider Gut DNA Shows Prey Remains Detectable for Days, Offering New Ecological Tool

A team led by Jeffery Marker at Karlstad University fed captive wolf spiders (Lycosidae) with Drosophila hydei, Gryllus bimaculatus and Coecobrya tenebricosa after an average starvation period of about 17 days. By sampling the spiders at intervals from immediately after feeding to eight days later, and applying DNA metabarcoding targeting the mitochondrial COI gene, they showed that fruit-fly DNA remained detectable for up to 120 hours and cricket DNA for up to 96 hours, with calculated detection half-lives of roughly 41.6 hours and 15.2 hours respectively.

Springtail DNA was recovered in fewer than 9 % of samples, preventing a reliable half-life estimate. The findings demonstrate that spider gut contents can serve as short-term records of local prey communities, but also warn that negative results may reflect DNA degradation or methodological limits. Researchers suggest future work account for factors such as prior gut contents, starvation length and metabolic differences.