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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
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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
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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
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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)
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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
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biosecurity built on science
Thank you