DNA Barcoding: A Reliable Method for the Identification of Thrips Species (Thysanoptera, Thripidae) Collected on Sticky Traps in Onion Fields

SIMPLE SUMMARY: Thrips species (Insecta, Thysanoptera) identification using traditional approach is not an easy. In the present study, DNA barcoding was used to support the thrips species characterization of a wide collection sampled in onion fields. Our findings confirmed the selected method as a simple and accurate approach identifying major thrips species, characterizing successfully nearly 86% of the samples collected in nine main species. The results here reported underlined the role of genetic markers as a valuable and useful method for species identification, especially when the morphological approach is unsure or even impossible. ABSTRACT: Several thrips species (Insecta, Thysanoptera) are globally known as important crop pests and vectors of viral diseases, but their identification is difficult because of their small body size and inconspicuous morphological differences. Sequencing variation in the mitochondrial cytochrome c oxidase I (COI) region has been proven to be useful for the identification of species of many groups of insect pests. Here, DNA barcoding has been used to identify thrips species collected with the use of sticky traps placed in an open onion field. A total of 238 thrips specimens were analyzed, 151 of which could be identified to species and 27 to genera belonging to the family Thripidae. Fifty-one specimens could not be assigned to any genus, with the closest BLAST match in the GenBank queries being below 98%, whilst six specimens were not recognized as Thysanoptera. The results indicate that, although there are a few pest thrips species not yet barcoded, most of the species that may cause damage to crops in Europe are represented in GenBank and other databases, enabling correct identification. Additionally, DNA barcoding can be considered a valuable alternative to the classic morphology method for identification of major thrips species.