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biosecurity built on science
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?
biosecurity built on science
Stable isotope geographic markers: δ2H and δ18O
99.985% 0.0026–0.0184%
O88 O10899.76% 0.20%
Light Heavy
biosecurity built on science
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?
biosecurity built on science
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
biosecurity built on science
Gathering data to develop relevant isoscapes
August
December
Australia Asia
δ2H: www.waterisotopes.orghttp://www.ansto.gov.au/AboutANSTO/MediaCentre/News/ACS101040 July 2016
biosecurity built on science
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?
biosecurity built on science
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
biosecurity built on science
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