Data for: Spider webs as efficient passive samplers of airborne fungal eDNA in forests: a case study with Hymenoscyphus fraxineus

Monitoring airborne inoculum of pathogens is important for plant disease surveillance. Here, we evaluate spider webs as passive environmental DNA (eDNA) samplers for detecting the pathogenic fungus Hymenoscyphus fraxineus, the causal agent of ash dieback, in a forest environment. In a temperate mixed forest, we compared two types of spider webs (orb and sheet webs) with a conventional passive sampler (filter paper) over matched day (orb) and week (sheet) deployments. Laboratory validation confirmed that webs exposed to airborne spores from apothecia yield positive qPCR signals. Across seven field sampling campaigns, both a species‑specific qPCR (Hfrax) and a broad fungal assay (FQ) detected fungal eDNA on spider webs more reliably and at higher relative quantities than on filter paper. In daily and weekly pairs, orb and sheet web vs filters, the median ΔCq (filter − web) was above 4 for both qPCR assays (Wilcoxon paired, p < 0.05), which corresponds to more than a 10-fold difference in the amount of target DNA. This study provides proof of concept for using spider webs as scalable, low-cost tools suitable for targeted (qPCR) surveillance to complement aerobiological networks.