<em>Wolbachia</em> and DNA Barcoding Insects: Patterns, Potential, and Problems

<div><p><em>Wolbachia</em> is a genus of bacterial endosymbionts that impacts the breeding systems of their hosts. <em>Wolbachia</em> can confuse the patterns of mitochondrial variation, including DNA barcodes, because it influences the pathways through which mitochondria are inherited. We examined the extent to which these endosymbionts are detected in routine DNA barcoding, assessed their impact upon the insect sequence divergence and identification accuracy, and considered the variation present in <em>Wolbachia</em> COI. Using both standard PCR assays (<em>Wolbachia</em> surface coding protein – <em>wsp</em>), and bacterial COI fragments we found evidence of <em>Wolbachia</em> in insect total genomic extracts created for DNA barcoding library construction. When >2 million insect COI trace files were examined on the Barcode of Life Datasystem (BOLD) <em>Wolbachia</em> COI was present in 0.16% of the cases. It is possible to generate <em>Wolbachia</em> COI using standard insect primers; however, that amplicon was never confused with the COI of the host. <em>Wolbachia</em> alleles recovered were predominantly Supergroup A and were broadly distributed geographically and phylogenetically. We conclude that the presence of the <em>Wolbachia</em> DNA in total genomic extracts made from insects is unlikely to compromise the accuracy of the DNA barcode library; in fact, the ability to query this DNA library (the database and the extracts) for endosymbionts is one of the ancillary benefits of such a large scale endeavor – for which we provide several examples. It is our conclusion that regular assays for <em>Wolbachia</em> presence and type can, and should, be adopted by large scale insect barcoding initiatives. While COI is one of the five multi-locus sequence typing (MLST) genes used for categorizing <em>Wolbachia</em>, there is limited overlap with the eukaryotic DNA barcode region.</p>