Project Leader, Organisation
David Murphy, Queensland University of Technology
PBCRC2111 (https://www.pbcrc.com.au/publications/pbcrc2272/) demonstrated Sr isotopes and trace metals as a powerful tool for geographic discrimination, but the method was limited to fruit flies and required pooling of samples (5-20 flies per analysis).
Continued method development at QUT has led to a novel MS-MS mode Sr isotope analysis and improved digestion methods that, importantly, allow analysis using single flies (PBCRC SI20074).
This project intends to extend this ew technique to beetles, bugs and moths relevant o the National priority plant pests lists (NPPP, 2016), testing digestion methods and detection limits towards a generic tool for determining natal origins of any biosecurity risk pest.
Objectives and impact
The ability to discriminate geographic origin of a biosecurity threat is immensely valuable for biosecurity decision-making. Unfortunately, when a biosecurity threat is first encountered there is generally limited material available. Knowing how much material is required for successful analysis of different species will pre-empt sub-sampling needs for timely outcomes.
Insect species relevant to the National Priority Plant Pest List will be chosen based on a variety of functional groups such as leaf-chewing moths (eg Lymantria), sap-sucking busg (eg BMSB) and wood boring beetles (eg longhorn beetles). This is vital as it is hypothesised from preliminary data that different feeding methods produce different trace metal content, eg BMSB has Sr concentrations 6x lower that of fruit flies. The consequence impacts on Sr isotope analysis which is critical to origins assessment. Viability of additional Pb isotope analysis will also be investigated. The key output will be a manuscript with the impact is peer-reviewed evidence of the potential for this technology beyond fruit flies and methods tailored accordingly for timely assessment of origins.
The first object of this project is to assess how variation in feeding styles affects the concentration of the provenance sensitive element Sr in insects. To do this twelve insect species with different feeding types and that are either on the National Priority Plant Pests list (NPPP, 2016) or are proxy for insects on the NPPP have been collected.
The second objective is to assess the Sr concentration of the sampled insects to evaluate how much insect tissue is required to be able to acquire a sufficiently precise Sr isotope analysis to be of use for provenance studies. To do this we have developed an efficient method for dissolving any insect type such that the Sr concentration of the insect can be analysed by conventional ICPMS trace element analysis.
The third object is continued development of Sr isotope analysis using MS-MS ICPMS. By testing the technique on the new generation Thermo iCap TQ ICPMS we have decreased the quantity of Sr required for Sr isotope analysis tenfold and increase the precision to 0.3%.
Now that the techniques for the project have been defined it will be straightforward to acquire the remaining data for the project in plenty time for on time completion of the project on June 30th.