Leaf beetles (Coleoptera: Chrysomelidae), with more than 37,000 species worldwide and about 2,100 in the Mediterranean region, are an ecological and economical relevant family, making their molecular identification of interest also in agriculture.
More...Leaf beetles (Coleoptera: Chrysomelidae), with more than 37,000 species worldwide and about 2,100 in the Mediterranean region, are an ecological and economical relevant family, making their molecular identification of interest also in agriculture. This study, part of the Mediterranean Chrysomelidae Barcoding project, aims to: i) develop a reference COI library for the molecular identification of the Euro-Mediterranean Chrysomelidae; ii) test the efficiency of DNA barcoding for leaf beetles identification; iii) develop and compare optimal thresholds for distance-based identifications estimated at family and subfamily level, minimizing false positives and false negatives. Within this study, 889 COI nucleotide sequences of 261 species were provided; after the inclusion of information from other sources, a dataset of 7,237 sequences (542 species) was analysed. The average intra-interspecific distances were in the range of those recorded for Coleoptera: 1.6%-24%. The estimated barcoding efficiency (~94%) confirmed the usefulness of this tool for Chrysomelidae identification. The few cases of failure were recorded for closely related species (e.g., Cryptocephalus marginellus superspecies, Cryptocephalus violaceus-Cryptocephalus duplicatus and some Altica species), even with morphologically different species sharing the same COI haplotype. Different optimal thresholds were achieved for the tested taxonomic levels, confirming that group-specific thresholds significantly improve molecular identifications.
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