Illuminating Entomological Dark Matter with DNA Barcodes in an Era of Insect Decline, Deep Learning, and Genomics

Most insects encountered in the field are initially entomological dark matter in that they cannot be identified to species while alive. This explains the enduring quest for efficient ways to identify collected specimens. Morphological tools came first but are now routinely replaced or complemented with DNA barcodes. Initially too expensive for widespread use, these barcodes have since evolved into powerful tools for specimen identification and sorting, given that the evolution of sequencing approaches has dramatically reduced the cost of barcodes, thus enabling decentralized deployment across the planet. In this article, we review how DNA barcodes have become a key tool for accelerating biodiversity discovery and analyzing insect communities through both megabarcoding and metabarcoding in an era of insect decline. We predict that DNA barcodes will be particularly important for assembling image training sets for deep learning algorithms, global biodiversity genomics, and functional analysis of insect communities.