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Exploiting Hydrogen and Oxygen as Components of a Natal Origin Biogeochemical Marker is Challenging but Promising

(PBCRC2111)

Karen Armstrong & Peter Holder (BPRC)David Murphy & Karine Harumi Moromizato (QUT)

Peter Crisp (SARDI)Bill Woods (DAFWA)

Solomon Balagawi (NSW DPI)

withRobert Van Hale & Dianne Clarke (Univ. Otago)

Plant Biosecurity Cooperative Research Centre

biosecurity built on science

Natal origins of fruit flies

Non-established

Potentially breeding

Confirmed breeding population

15 M

4 M

2 M

1 M

0 M

Esti

mat

ed c

osts

N

ZD

e.g. estimated cost QFF incursion, NZ (2015)

Is this fly from a locally established population or has it just arrived?

Do we know where from?

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Stable isotope geographic markers: δ2H and δ18O

99.985% 0.0026–0.0184%

O88 O10899.76% 0.20%

Light Heavy

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Challenges for biosecurity application

Technical:‐ Can geographic areas be resolved at a relevant spatial scales?

‐ Generation of reference ‘isoscapes’

‐ Can existing technology be adapted for smaller insects?

‐ Can conclusions be drawn from only a few insects?

Biological:‐ How faithful is the environment-to-plant-to-insect signature?

‐ Does polyphagy matter?

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How good is the spatial resolution within Australia?

xx xx

x

xxxxx

xxxxx

x

xxxx

xxx

xx

x xxxx

xxxx

xxxx

xxx

Kunanara

Broome

Carnarvon

x xxxx

bb

a

Fishers LSD=5%

Empirical evidence of regional discrimination

National International

Grey Lynn incursion, AKL, NZ (2015)

Arophelus ferus Lubomír Klátil

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Gathering data to develop relevant isoscapes

August

December

Australia Asia

δ2H: www.waterisotopes.orghttp://www.ansto.gov.au/AboutANSTO/MediaCentre/News/ACS101040 July 2016

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Now understand the fractionation relationship

-70 -50 -30 -10 10 30 50 70 90-5

0

5

10

15

20

25

30Q-Fly and medfly water to wing 2H and 18O Δ

Q-fly T1 medfly T1 Q-fly T2 medfly T2 Q-fly T3

medfly T3 Water T1 Water T2 Water T3

δ2H

δ18O

How many individuals needed for confident assignment?

Are these NZ H. armigera from NZ?

Are these AUS H. armigera from NZ

(Naïve Bayes analysis) (Boosted regression

tree analysis)

Choosing the right tissue for analysis

Adult flies on treatments for 13 diff. periods, 0 – 90 days:

T1 starved (no water) T2 control (same water) T3 water enriched for d2H & d18O

5 samples per time period, various tissues used for H & O analysisResults pending….

Does adult feeding influence the natal signature via tissue turnover?

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Summary - H & O isotope ratio markers of origin

Challenges

• Developing relevant reference isoscapes – local, regional, international?

• Developing a multivariate systems ‘model’ for end user application

Promises

• Technology to analyse single insects rapidly is possible

• Number of insects needed is low

• We understand the δ2H & δ18O signature food-to-fly transmission

• Wild fly regional differences can be greater than any seasonal or host variation

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The End-User Advocate’s perspective

Various uses for knowledge of natal origins:- declarations of area freedom- indicator of regions generating infested produce- understand local pathway risk – landscape use, preferred sites & travel

corridors

Ultimate end users/beneficiaries:- horticultural industries susceptible to fruit fly- inter-state quarantine (regulators and risk managers)- funding providers for regulatory activities, funding bodies for better

targeted research for international market access

Climate change - Qfly range expanding so NZ, Tasmania and South Australia under

increasing pressure to maintain area freedom = intensified interest in evidence for source of a breach.

Bernie Dominiak, NSW DPI

biosecurity built on science

Thank you