A tale of two fluids: does storing specimens together in liquid preservative cause DNA cross‐contamination in molecular gut‐content studies?

The study of food webs and trophic interactions increasingly relies onPCR‐based molecular gut‐content analysis. However, this technique may be prone to error from contamination of minute quantities ofDNA; i.e., simply storing specimens together in a liquid medium may lead to cross‐contamination. In this study, we usedPCRto determine the contamination rate when (1) specimens were stored together in 95% ethanol for various time periods, and (2) predators fall into ethylene glycol‐filled pitfall traps where the dying predator may inadvertently consume preyDNA‐contaminated liquid. We designed experiments andPCRprimers to quantify the risk of contamination for both situations and found no contamination by storing specimens together in 95% ethanol. Furthermore, zero predators contained preyDNAin their gut contents from imbibing preyDNA‐contaminated ethylene glycol. These results support the use of mass sampling techniques, like wet pitfall traps, for molecular gut‐content analysis.