The Scirtothrips dorsalis species complex: Endemism and invasion in a global pest

Authors: DICKEY, AARON - University Of Florida; KUMAR, VIVEK - University Of Florida; HODDLE, MARK - University Of California - Cooperative Extension Service; FUNDERBURK, JOE - University Of Florida; Morgan, John; JARA-CAVIERES, ANTONELLA - University Of Florida; Shatters, Robert - Bob; OSBORNE, LANCE - University Of Florida; McKenzie, Cindy

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/27/2015
Publication Date: 4/20/2015
Citation: Dickey, A.M., Kumar, V., Hoddle, M.S., Funderburk, J.E., Morgan, J.K., Jara-Cavieres, A., Shatters, R.G., Osborne, L.S., McKenzie, C.L. 2015. The Scirtothrips dorsalis species complex: Endemism and invasion in a global pest. PLoS One. https://doi.org/10.1371/journal.pone. 0123747
DOI: https://doi.org/10.1371/journal.pone.0123747

Interpretive Summary: Invasive arthropods pose unique management challenges in various environments, the first of which is correct identification. This task is particularly difficult if multiple species are morphologically indistinguishable but accurate identification can be determined with DNA barcoding provided an adequate reference set is available. The chilli thrips is a highly polyphagous plant pest with a rapidly expanding global distribution and this species, as currently recognized, may be comprised of multiple species. Here we report the development of a comprehensive DNA barcode library for the chilli thrips and additional nuclear genes obtained by next-generation sequencing for identification use within the complex. We also report the division of the chilli thrips complex, which consists of nine morphologically identical species and two morphologically distinguishable species. One member of the complex, here designated the South Asia 1 cryptic species, is highly invasive, feeds on multiple host plants, and is likely the species implicated in plant virus transmission. Two other species, South Asia 2, and East Asia 1 also feed on many plant species and appear to be at an earlier stage of global invasion. Other members of the complex only occur in their native range and vary with respect to pest status and diet. In addition to patterns of invasion, our results provide a framework for identifying individuals to species within the complex based on their DNA barcode.

Technical Abstract: Invasive arthropods pose unique management challenges in various environments, the first of which is correct identification. This apparently mundane task is particularly difficult if multiple species are morphologically indistinguishable but accurate identification can be determined with DNA barcoding provided an adequate reference set is available. Scirtothrips dorsalis is a highly polyphagous plant pest with a rapidly expanding global distribution and this species, as currently recognized, may be comprised of cryptic species. Here we report the development of a comprehensive DNA barcode library for S. dorsalis and seven nuclear markers via next-generation sequencing for identification use within the complex. We also report the delimitation of nine cryptic species and two morphologically distinguishable species comprising the S. dorsalis species complex using histogram analysis of DNA barcodes, Bayesian phylogenetics, and the multi-species coalescent. One member of the complex, here designated the South Asia 1 cryptic species, is highly invasive, polyphagous, and likely the species implicated in Tospoviruses transmission. Two other species, South Asia 2, and East Asia 1 are also highly polyphagous and appear to be at an earlier stage of global invasion. Other members of the complex are regionally endemic, varying in their pest status and degree of polyphagy. In addition to patterns of invasion and endemism, our results provide a framework both for identifying members of the complex based on their DNA barcode, and for future species delimiting efforts.