A DNA Barcode Reference Library for Trichoptera of Jingpo Lake: Taxonomic Diversity and Molecular Identification Basics.

Jingpo Lake in Northeast China is a vital aquatic ecosystem, yet it lacks baseline molecular data for its insects. Trichoptera (caddisflies) are excellent ecological bioindicators, but their accurate identification is often hindered by morphological similarities, life-stage limitations, and insufficient DNA barcode records. To address this gap, this study combined morphological identification with DNA barcoding to establish a local reference database. From 285 collected adult caddisflies, 105 representative specimens were selected for genetic analysis. The survey identified 22 species across 9 families, revealing four new records for China and six for Heilongjiang Province. Analyses confirmed the high efficacy of the COI marker, demonstrating low intraspecific genetic divergence (0.78%) and high interspecific divergence (17.80%), with a clear barcode gap separating all examined species. Species accumulation curves indicated robust sampling of the main genera, although expanded collection efforts could still uncover additional species. In conclusion, this study provides a valuable DNA barcode reference library for Trichoptera in the Jingpo Lake region. It establishes foundational data for regional biodiversity inventories and future ecological monitoring based on environmental DNA (eDNA) or metabarcoding approaches.