DNA barcoding: a new module in New Zealand’s plant biosecurity diagnostic toolbox

Abstract

Molecular methods for identification of high risk pests and pathogens have been employed for more than a decade to supplement standard diagnostic protocols. However, as the volume of traded goods continues to increase so does the breadth of taxa that diagnosticians need to deal with. Keeping pace by introducing more molecular tests that are typically species‐group specific is not an efficient way to progress. Since 2005 classical DNA barcoding using cytochrome oxidase I sequence has been employed routinely in New Zealand for the highest risk insect species (fruit flies and lymantriid moths). Subsequently a broader range of pests have been considered. Case studies are presented here for three important lepidopteran pests, Lymantria mathura (pink gypsy moth), Conogethes punctiferalis (yellow peach moth) and Hyphantria cunea (fall web worm), as well as a trial to identify miscellaneous border interceptions. While the data support the effectiveness of DNA barcoding for border diagnostics, they also raise issues around cryptic species identification and potential species discovery that could impact on operational biosecurity systems.

Species Delimitation and Global Biosecurity

“…For areas such as the delivery of national biosecurity obligations, immediate practical implications exist when delimitation is unclear. This is becoming increasingly apparent with the adoption of DNA sequence analysis and the generation of large single-gene datasets for both taxonomic research98 and diagnosis of high risk pest species 99. The two species analysed here represent extremes of the taxonomic problems faced; one with a well-resolved phylogeny supporting large intra-specific variation ( B. tabaci ) and another with a poorly resolved phylogeny and limited genetic diversity that does not support the current sub-species divisions ( L. dispar ).…”

Current progress in DNA barcoding and future implications for entomology

“…Two groups, tussock moths (Lepidoptera: Lymantriidae: Lymantria and Orgyia ) and fruit flies (Diptera: Tephritidae), were initially selected for test cases. Subsequently, identification performance was also tested using three important pest groups of Lepidoptera, a species group of Lymantria , yellow peach moth (Crambidae: Conogethes ) and fall web worms (Arctiidae: Hyphantria ) (Armstrong 2010). Scheffer et al .…”

Demographic Trends in Mixed <I>Bemisia tabaci</I> (Hemiptera: Aleyrodidae) Cryptic Species Populations in Commercial Poinsettia Under Biological Control- and Insecticide-Based Management

“…Information gleaned from these data was used to describe the genetic variation within the B. tabaci cryptic species complex (Frohlich et al 1999, Shatters et al 2009, Dinsdale et al 2010, De Barro et al 2011, and has been used by the current authors and others (Ahmed et al 2012) to identify B. tabaci cryptic species. However, a 650-bp fragment of the 5Ј region of this gene (also known as the DNA barcode) has been widely adopted for use as a genetic marker for the identiÞcation of animals, including pest insects, in both an applied and a research context (Hebert et al 2003, Armstrong 2010, Bonants et al 2010, Frewin et al 2013). At the time of writing this article, DNA barcodes have been generated for 138,537 insect species (refer to BOLD: www.boldsystems.org, Ratnasingham and Hebert 2007).…”