DNA barcoding, an effective approach for the identification of thrips (Thysanoptera: Thripidae) in citrus orchards

Abstract

Thrips are serious crop pests with a worldwide distribution. The first step in the design of control methods is accurate species identification. However, the morphological identification of thrips can be complex, especially as there is morphological variation amongst individuals of the same species. Analyzing a fragment of cytochrome c oxidase subunit I (COI) has been used successfully in the identification of insects and other arthropods. Citrus is among the most important crops in the world, and Mexico is one of the largest producers. Despite this, formal reports on the species diversity of thrips found in Mexican citrus orchards are scarce. We explored the species diversity of thrips in selected citrus orchards (of Mexican orange, Key lime and Persian lime), based on morphological taxonomy and on partial sequences of COI. We analyzed 111 thrips specimens, distributed in two genera: Frankliniella, including Frankliniella insularis, Frankliniella invasor and Frankliniella occidentalis; and Scirtothrips, including Scirtothrips citri and Scirtothrips dorsalis. Frankliniella insularis and F. invasor were the most abundant species in Mexican orange (Citrus × sinensis) and Persian lime (Citrus × latofolia) orchards. Scirtothrips dorsalis was the most abundant species in Key lime orchards (Citrus × aurantiifolia). Analysis of molecular variance (AMOVA) and haplotype analyses performed on F. insularis sequences (the most abundant species) showed no significant effect of geographical origin or plant host on its genetic population structure. DNA barcoding is a valuable method to complement the morphological identification of thrips in citrus orchards, allowing more accurate identification to species level.