Morphological taxonomy and DNA barcoding: Should they be integrated to improve the identification of chironomid larvae (Diptera)?

Among freshwater benthic fauna, one of the most frequently observed groups of insects is midges of the family Chironomidae (Diptera). Their identification to the species level by morphology alone is difficult or even impossible (e.g., at larval and pupal stages). This basically results from their high phenotypic plasticity, the existence of cryptic species, and the need for access to complete, identified individuals for comparison. Consequently, DNA barcoding is becoming more popular. This technique uses the sequence of base pairs in a specific DNA fragment section as barcodes for individual species. This method not only allows the identification of sister species but also facilitates the discovery of new, previously unknown ones. Despite these benefits, molecular techniques have some limitations, including the lack of a complete barcode library and the need for access to properly purified genetic material. What is needed is to combine new taxonomic methods with elementary knowledge about the ecology of individual chironomid species. In this study, we have attempted to compare and synthesize the advantages and disadvantages of conventional vs. molecular methods of identification and to show the benefits of their integration into a hybrid approach. The suggested integration seems to be an optimal methodological solution that includes elements of Artificial Intelligence to accurately assess chironomid communities in terms of qualitative structure, which usually indicates the biodiversity of freshwater ecosystems. Thus, it is a fundamental tool for assessing the natural potential of water bodies according to the principles of the EU Biodiversity Strategy for 2030.