Could fruit fly polyphagy compromise trace elements as markers of natal origin? (2111)

Transcription

1 Could fruit fly polyphagy compromise trace elements as markers of natal origin? (2111) Dr K Armstrong (Lincoln University), P Holder (Lincoln University), D. Murphy (QUT), C. Allen (QUT), K. Harumi Moromizato (QUT), A. Strazzabosco, P. Crisp (SARDI). The potential for trace element and/or stable and radiogenic isotope signals to differentiate high risk pest insects from different geographic places has been demonstrated elsewhere. However, one of the key questions is, how reliable is this as a tool for endusers if biological and environmental factors cause significant, spatially-unrelated, heterogeneity in the biogeochemical signal? One such factor might be the polyphagous nature of fruit flies. If different species of plant at the same geographic location differentially influence the signal from the soil, then that expressed by the developing larvae may also vary. This would be further compounded by not knowing which plant species the larva of a trapped adult fly had originated from. A preliminary experiment in Presenting author s biography South Australia to test this is described, using different fruit hosts from the same orchard area. Mass spectroscopy analysis of the resulting flies suggests that host has no effect for the majority of trace elements; those for which there did appear to be an effect were amongst the common, biologically active elements, which in any case were to be omitted as markers. Thus, for trace elements at least, polyphagy is unlikely to be of concern. The fly samples here were also used to show that, compared to use of an established method needing pooled flies for the highly laborious acid dissolution and solution ICPMS analysis, laser-ablation ICPMS is a much more efficient and sensitive method that enables use of individual fly body parts. Karen Armstrong is a senior researcher in applied entomology. She focusses on novel uses of molecular and chemical technology to develop fit-for-purpose diagnostic tools for biosecurity, as well as to tackle more fundamental questions within the broader scope of plant bioprotection. Karen heads the Diagnostics Theme in the Better Border Biosecurity collaboration, is an adviser to the QUADs Diagnostic DNA Barcoding project and supervises several PhD students at Lincoln University on topics relevant to biosecurity. Dr Karen Armstrong Karen.Armstrong@lincoln.ac.nz Science Exchange 2015 Conference Handbook 83

2 Session Nine: Sharper responses to incursions Presentation title: Could fruit fly polyphagy compromise trace elements as markers of natal origin? Presenter: Karen Armstrong

3 PBCRC2111 Decision intelligence: determining pest natal origins Karen Armstrong, BPRC Peter Holder (BPRC), Dave Murphy, Charlotte Allen, Alice Strazzabosco, Karine Harumi Moromizato, Irina Kinaev (QUT), Peter Crisp (SARDI), Bill Woods (DAFWA), Andrew Jessup & Bernie Dominiak (NSW DPI) Plant Biosecurity Cooperative Research Centre

4 The problem(s).. To decide on the status of a quarantine zone e.g. fruit fly outbreaks Applying the COP based on conservative information Costly consequences of declaring an outbreak economic, environmental, social impacts Knowing where a fly had come from would be of significant benefit locally established or new arrival? Can natural abundance biogeochemical markers (stable isotopes & trace elements) be used to determine origins? Of individual, small insects At a relevant range of spatial scales Taken to proof of concept

5 Heterogeneity of isotopes & trace elements in insects Are you what you eat? Locale geology+environment = soil = plant = insect = analytical result Not entirely, because of biology.. Locale geology+environment = soil ~ plant ~ insect ~ analytical result But can we minimize the biological influence? rationalise elements used non-essential trace elements esp. Strontium & Lead isotopes 87 Sr/ 86 Sr, 206 Pb/ 207 Pb/ 208 Pb understand which biological aspects are important

6 e.g. Could polyphagy compromise markers of natal origin? Lockston research orchard, SA - different fruit tree species, same place Lab rear medfly & Qfly: x5 fruit species x6 trees x6 fruit [pool x6 flies/fruit] x2 fly species = 660 samples

7 Challenges and issues arising from the research a) Numbers of flies emerging very low Fruit too ripe? Not enough flies for replication Medfly Qfly Oranges Nectarines Apricots 45 1 b) Compounded by need for pooled samples This early technology not sensitive for single flies Grapefruit 0 0 Grapes 0 0 c) Further compounded by inter-lab teething problems Inter-disciplinary learning curve a fly is not a rock

8 Results..52 elements measurable, 18 non-essentials Orange Nectarine Apricot medfly mix mix mix Qfly Qfly Qfly Qfly mix Qfly Medfly Qfly medfly medfly mix medfly ppm K P Mg Ca Na Fe Hierarchical cluster analysis no effect by fruit type Zn Mn Cu Al Sr ppb Ba Pb Rb Ti <0.000 < Ni Mo Sn To be repeated this season! Cr < W Li Zr Co Ga V <0.000 < <0.000 Cd La < Ce < Sb

9 Working on technological improvement Lazer ablation of single flies x Eye x Leg x Wing Head pressed pellet internal std

10 Lazer Ablation strontium now measurable in single insects N = 10 Sr88 (ppm) SD (%) Pb206 (ppm) SD (%) Pb207 (ppm) SD (%) Pb208 (ppm) SD (%) Pb 208/206 Pb 207/206 Body_Press_Pellet ± ± ± ± Head_Press_Pellet ± ± ± ± Legs ± ± ± ± Wings ± ± ± ± Mean, RSD

11 The immediate plan, with end user input. Customised isoscapes Mining public data + strategic soil & plant sampling Rearing flies on geographically collected fruit Lisbon lemons nce.gov.au/

12 The End-User Advocate s perspective Bernie Dominiak, NSW DPI Various uses for knowledge of natal origins: - Declarations of area freedom - Identification of which market access protocols have failed if they failed - Identification of within-country source - Presence of sterile insect contaminants - Research on flight distance, without using dye, for new ISPMs - Pathway risk understand landscape use i.e. preferred sites and travel corridors Ultimate the end users/beneficiaries: - State quarantine, horticultural industry, the public, tech providers, researchers

13 Thank you Karen Armstrong Acknowledgements Better Border Biosecurity, NZ Robert Van Hale, University of Otago, NZ University of Adelaide

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