March 16, 2022

Numerous species have been driven to the brink of extinction from overharvest, motivated by the highly lucrative illegal trade of species that are used as components of traditional medicines. Bear bile is a prized component of traditional Asian medicines where increasing demand for this ingredient has led to declines in Asiatic bear populations. While laws exist to prevent poaching and trafficking of bear products, illegal trade persists given a preference for wild Asian bear bile with spill-over demand to surrogate sources, including American black bears (Ursus americanus). Mitochondrial DNA sequencing can be used for products that putatively contain bear bile. While useful, sequencing reactions can be undermined by inhibitors in bile and a lack of sensitivity to identify bear DNA in highly diluted products. Quantitative PCR (qPCR) assays are extremely target specific in detecting trace levels of nucleic acids while concomitantly evaluating assay inhibition that can lead to false negative results and are thus increasingly applied to low quality/quantity DNA applications. The aim of this study is to develop a qPCR method to amplify and detect low levels of bear DNA from highly diluted bile samples, including bile within liquors and liqueurs. Samples of unmixed bear bile, bile diluted with 5% and 50% ethanol, and bile diluted with whiskey and merlot were examined and quantified. Overall, this study provides a rapid, sensitive, and specific test to identify bear DNA from bile to assist wildlife enforcement.