High-throughput sequencing for life-history sorting and for bridging reference sequences in marine Gerromorpha (Insecta: Heteroptera). Gerromorpha

Accurate information and association of larval specimens with adults is a major challenge in insect taxonomy. Fortunately, it is now possible for non-experts to sort specimen-rich bulk samples with DNA barcodes rapidly and cost-effectively. We demonstrate this process via nanopore barcoding of a collection of 757 marine insects (Insecta: Gerromorpha), of which 615 were nymphs and two of the six sampling localities did not have co-occurring male adults. We successfully associated 738 specimens to nine gerromorphan species, which would have been impossible with morphology alone. We also highlight two distinct, non-overlapping Gerromorpha COI sequence databases on GenBank, a consequence of using two different primer sets to amplify different regions of COI. This issue inevitably hinders species identifications with DNA-based methods, particularly for poorly represented groups such as marine insects. We bridged these databases by generating mitogenomes, where the full-length COI sequence is assembled as a by-product. We believe that this work will inspire future studies to incorporate DNA-based methods for more adult-larval association studies and for enhancing existing genetic resources, especially on understudied groups.