External <scp>DNA</scp> contamination and efficiency of bleach decontamination for arthropod diet analysis

DNA metabarcoding is increasingly used to analyze the diet of arthropods, including spiders. However, high sensitivity contamination makes it difficult apply organisms obtained from mass-sampling methods such as pitfall traps. An alternative hand-sample spiders, but unclear how effectively this prevents external contamination, especially with new knowledge showing wide spread eDNA in environment. Protocols using bleach remove have been tested on several invertebrates, though testing both and spiders lacking. Here, we wolf (Lycosidae) assess risk trapping hand sampling, efficacy decontamination. We first conducted a experiment where placed traps containing medium nonprey insect species simulate contamination. also compared sampling by collecting sampling. Spiders method comparison were either bleached or untreated, then metabarcoded multiple primer pairs. The resulted almost all traps, which was successfully eliminated bleaching. Interestingly, there no difference number amplicon sequence variants (ASVs) detected per spider between bleaching significantly fewer ASV detections for methods. Additionally, bleaching, not method, affected taxonomic composition hand-sampled pitfall-trapped indicating similar levels Our results are confirm that can be together sampled does necessarily exclude Thus, studies should address field-sampled regardless method.