Oral Presentation Science Protecting Plant Health 2017

How robust are stable isotope and trace element signatures for the assessment of a fruit fly's geographic origin? (4257)

Karen F Armstrong 1 , Peter W Holder 1 , David Murphy 2 , Daniel Weimer 2 , Karine H Moromizato 3 , Irina Kinaev 3 , Peter Crisp 4 , Bill Woods 5
  1. Lincoln University, Lincoln, CANTERBURY, New Zealand
  2. Earth, Environmental and Biological Sciences, Queensland University of Technology, Brisbane, QLD, Australia
  3. Central Analytical Research Facility, Queensland University of Technology, Brisbane, QLD, Australia
  4. Entomology, South Australian Research and Development Institute, Adelaide, SA, Australia
  5. Entomology, Department of Agriculture and Food of Western Australia , Perth, WA, Australia

To distinguish a fruit fly in a trap as either a new arrival or from a locally breeding population has significant implications for the degree of risk posed, and hence for the level and nature of the response required. Elsewhere, combined stable isotope and trace element signatures have held up to the proof of principle that they can distinguish geographic regions of origin for several insect species. However, how robust this technique is for biosecurity decision-making needs to be systematically assessed.

Here we summarise highly coordinated research to test the geographic resolution that may be usefully afforded for fruit fly surveillance in Australia and New Zealand. Signatures expressed in medfly and Q-fly reared on lemons harvested from high risk regions of Queensland, New South Wales, South Australia, Western Australia and North and South islands of New Zealand, were obtained for strontium (Sr), hydrogen (H) and oxygen (O) isotopes plus non-essential trace element concentrations. This dataset, comprising 86 lemon collection points and 7,263 fruit flies, reveals (1) that fruit fly Sr isotope signatures usefully reflect that of the underlying geology, (2) there was significant variation in the west of Australia compared with that of the east and with New Zealand, and therefore correspondingly (3) that regional distinctions are possible between fruit flies, but also possibly at the township level around the southwest Australia. In addition, H and O results will be presented; these are anticipated to enhance regional provenance determination, but not near-scale discrimination.