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

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.