Making metabarcoding more meaningful: Leveraging natural history collections to develop DNA reference libraries

Metabarcoding is a powerful tool for rapidly documenting and monitoring arthropod communities. However, insights are often limited by the lack of robust reference libraries. Museum collections offer an untapped resource for generating these reference libraries, housing hundreds of thousands of vouchered specimens with species identities. At the core genomics facility of the California Academy of Sciences, and in collaboration with a larger initiative to barcode all insects in California, we have been developing protocols to produce DNA barcodes from historical insect specimens across various ages and taxonomies in a high-throughput and cost-effective manner. We have tested several extraction protocols, amplification methods, and sequencing approaches, and thus far have extracted DNA from over 7,000 insect museum specimens, covering 23 orders and over 1,200 genera. A priority of the project thus far has been generating barcodes from identified aquatic insects. This data will be pivotal for metabarcoding projects focused on riparian habitats, enabling finer-scale assessments of community structure. We are focusing on developing protocols that are accessible and financially feasible, allowing other institutions to adopt the approaches. Through this, we can move towards harnessing the immense knowledge housed in museums and improve insights generated from metabarcoding data.