Assessment of loci for DNA barcoding in the genus Thrips (Thysanoptera:Thripidae)

Identification of the juveniles of economically important thrips species on imports by morphology alone can be challenging and culturing is usually required. In the case of EU quarantine species such as Thrips palmi, rapid and accurate identification is essential. DNA barcoding using the Cytochrome oxidase I (COI) gene has become a popular technique for species identification; however, in some invertebrate genera COI has been shown to provide insufficient variability for species discrimination. This study presents a comparison of five different loci to investigate their ability to discriminate a small number of Thrips species. All five loci discriminated the species by neighbour-joining tree and varying degrees of discrimination were determined upon further investigation of the intraspecific and interspecific distances. Two distinct COI clades were observed for T. Palmi and judged to be COI haplotypes when data from the other four additional loci and geographical collection data were taken into consideration. COI was shown to provide sufficient variation to be used in future DNA barcoding efforts within the genus Thrips.