Abstract
Due to the difficulties associated with detecting and correctly identifying mirids, developing an accurate species identification approach is crucial, especially for potential harmful species. Accurate identification is often hampered by inadequate morphological key characters, invalid and/or outdated systematics, and biases in the molecular data available in public databases. This study aimed to verify whether molecular characterization (i.e. DNA barcoding) is able to identify mirid species of economic relevance and if species delimitation approaches are reliable tools for species discrimination. Cytochrome c oxydase 1 (cox1) data from public genetic databases were compared with new data obtained from mirids sampled in different Italian localities, including an old specimen from private collection, showing contrasting results. Based on the DNA barcoding approach, for the genus Orthops, all sequences were unambiguously assigned to the same species, while in Adelphocoris, Lygus and Trigonotylus there were over-descriptions and/or misidentifications of species. On the other hand, in Polymerus and Deraeocoris there was an underestimation of the taxonomic diversity. The present study highlighted an important methodological problem: DNA barcoding can be a good tool for pest identification and discrimination, but the taxonomic unreliability of public DNA databases can make this method useless or even misleading.
Highlights
The family Miridae (Hemiptera: Heteroptera) is comprised of 11,020 described species, subdivided into eight subfamilies; members of the family are distributed across every biogeographic region (Schuh 1995, 2013; Cassis & Schuh 2012)
The morphological and molecular data of this study unambiguously assigned the 43 specimens of Miridae to seven species belonging to six genera of the subfa milies Mirinae and Deraeocorinae: Adelphocoris line olatus, Lygus rugulipennis (Poppius, 1912), Lygus wagneri (Remane, 1955), Orthops kalmii (Linnaeus, 1758), Polymerus vulneratus (Panzer, 1805), Trigonotylus caelestialium (Kirkaldy, 1902) and Deraeocoris serenus (Douglas & Scott, 1868)
The cox1 data of these specimens were compared with sequences from public genetic databases (BOLD, GenBank) attributed to congeneric species showing contrasting results accord ing to the genera
Summary
The family Miridae (Hemiptera: Heteroptera) is comprised of 11,020 described species, subdivided into eight subfamilies; members of the family are distributed across every biogeographic region (Schuh 1995, 2013; Cassis & Schuh 2012). Under certain conditions, some pests are able to switch from phytophagy to zoophagy, turning themselves into useful natural enemies that are employed in biological control programs, along with zoophagous species (Schaefer & Panizzi 2000; Wheeler 2001; Ferreira et al 2015). According to morphological and molecular revisions, the Miridae present a large number of taxonomically difficult lineages with polyphyletic or paraphyletic species groupings (Park et al 2011; Cassis & Schuh 2012; Raupach et al 2014; Gwiazdowski et al 2015). The information that has been obtained has been used to address taxonomic issues as well as the presence of pro blems in the molecular identification of investi gated mirid species due to the misidentification of specimens, the presence of inaccuracies in public databases, the lack of recognition of cryptic diver sity and/or the over-splitting of species
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