Petola is the essential element in traditional salt production in Sečovlje Salterns. It is a few millimeters-thick microbial layer that enables the harvesting of high-quality, pure, and white salt. It has been observed that one of the pests damaging the petola is a non-biting midge (Chironomidae) or, more precisely, its larvae. DNA barcoding is a method that serves as a complementary or alternative approach to traditional species identification based on morphology. In this method, specific regions of DNA (DNA barcodes) that are highly conserved within a species but sufficiently variable among species are analyzed to enable taxonomic differentiation. For most animal species, the most effective barcode is the 5′-region of the gene encoding the cytochrome c oxidase subunit I (COI). In this thesis, the sex of 13 adult non-biting midges, sampled in May 2024 in the vicinity of the crystallization ponds of the Sečovlje Salterns, was determined based on distinct morphological characteristics. We extracted DNA from specimens and amplified the COI region using modified Folmer primers LCO1490' and HCO2198'. The amplification products were ligated into vectors, which were then cloned in E.coli and prepared for sequencing. Analysis of the obtained nucleotide sequences revealed that all samples belong to the genus Chironomus. For three specimens, we unambiguously identified the species Chironomus salinarius. Based on genetic distances among the sequences, we concluded that all analyzed specimens most likely belong to this species. We rejected the previous assumption that the midges occurring in large numbers in the Sečovlje Salterns during spring belong to the species Halocladius varians.
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