WP 2 - The use of volatile organic compounds for the early detection of pests and pathogens ('Volatiles Detection')

Workpackage 2

Partners: Steve Woodward (Aberdeen), Ebel (Aberdeen), Tubby (FR), Preston (Oxford)

Technology for detecting volatile organic compounds (VOC) to find threats is used routinely at ports and by the military (www.smithsdetection.com). VOCs can be characteristic for microorganisms, insects and plant diseases (e.g. Miresmailli et al., 2010. Pest Manag. Sci. 66:916; Jansen et al, 2011. Ann. Rev.Phytopathol. 49:157). Modern gas chromatography mass spectrometry (GC-MS) and ion mobility spectroscopy (IMS) technologies are sensitive enough to detect VOCs at concentrations lower than one part per billion. Combining these it is highly likely that such ultra-sensitive technology could be parameterised to detect VOCs produced by plant pests/pathogens and attacked/diseased plants whilst being shipped (report from LWEC Tree Heath Phase 1 report).

This WP will investigate the production of VOCs by a number of 'model' pests and pathogens: Ceratocystis platani (plane canker), Fusarium circinatum (pine pitch canker), various Phytophthora spp., Pseudomonas syringae pv. aesculi (chestnut bleeding canker) and Brenneria quercina (oak bark canker), along with 2 alien long-horned beetles, Anoplophora glabripennis and A. chinensis, and the emerald ash borer (Agrilus planipennis). Cultures of these (obtained in collaboration with partners across the project) will be examined for production of VOCs through headspace sampling and adsorption onto solid phase extraction fibres (SPE). SPE provides an ideal adsorption material for this work, as small packs of it can be included in packaging used for the shipment of plants/plant materials for direct analysis. Any potentially unknown signature compounds will be isolated, purified and structurally characterised using NMR spectroscopy. Studies will then be conducted to identify if these signature VOCs are produced in detectable quantities in plant consignments. VOCs identified in culture will be quantified during interactions with plant tissues (shoots or roots of host trees), maintained in containment facilities, using head space sampling, SPE adsorption and GC-MS. VOCs from the affected plants will also be analyzed to determine if this approach could also be beneficial in addition to the detection of pest/pathogen VOCs. The final stage will be to evaluate if commercially available technology platforms can be parameterized to detect the various signature VOCs for routine use. In collaboration with Smiths Detection, we will determine the capacities of the currently available commercial apparatus to detect the target VOCs, both in air samples (head space sampling) and in SPE packs incorporated with plants in commercially used packing and transport systems. At this stage, interference in detection from background will be examined in detail: simple sample prep work may be required to remove interfering material and concentrate target molecules before identification. The commercially available instruments are designed to look for 'the needle in a haystack', whereby rare molecules of interest are in a much smaller concentration than common background VOCs. It may be that the best approach involves detection of a range of compounds as indicative of the presence of the alien organism, rather than the one 'magic bullet' target approach.

Deliverables
 • A library of VOC signatures from a range of pests and pathogens.
 • Protocols for the use of commercial, portable chemical analysis equipment for the detection of pathogens, pests and/or diseased plants.