Effective control of insect pests is required for maintenance of grain quality as well as access to both domestic and overseas markets. However, the continued use of phosphine, the major disinfestation tool, is now threatened by the development of high-level resistance in a number of pest species. Minimising phosphine resistance and maintaining phosphine as the chemical of choice for controlling grain insects is a major challenge facing pest managers in the stored grain industry. Any strategy to combat resistance must be underpinned by accurate knowledge of resistance development in the field. This fundamental knowledge is needed to support scientifically based resistance management.

Research outcomes:

1. Resistance alleles have been demonstrated to provide useful information previously unobtainable, and can be used on historical collections in storage.
2. Resistance alleles are moving within local landscapes and are increasing on farms that do not use phosphine. This is inferred by observations of increasing resistance allele frequency between collections of R. dominica taken in 2006 and 2011.
3. Movement studies showed that changes in walking behaviour or flight initiation were minimal between resistant and susceptible R. dominca. We infer from this that dispersal of resistance alleles is likely to occur at a similar rate as dispersal of susceptible alleles within local landscapes.
4. We identified a specific and exploitable metabolic weakness in insects carrying resistance alleles at the rph2 locus. We found that mutations in the rph2 locus cause hypersensitivity to arsenical compounds. We predict that compounds that can mimic the reactivity of arsenic are likely to be potent phosphine synergists and are likely to be preferentially toxic to resistant insects.
5. We found that resistance is highly conserved globally by using genetic complementation between strongly resistant Indian and Australian strains of R. dominica and T. castaneum. It appears that the same two genes are responsible for resistance in their respective species worldwide. Since rph2 is known to be the same between species, it is now likely that it is also found in highly resistant strains of other species.
6. For T. castaneum, the candidate gene list for rph1 has narrowed to two likely candidates, of which one has mutations in multiple strains that are likely to affect gene function. However the gene list for R. dominica rph1 remains less clear, with a gene list that still stands at ~100 genes.

Research implications

Implication 1

The research has shown that resistance alleles are moving in local areas and that they do not appear to provide any impediment to local dispersal. The frequency of resistance alleles appears to be increasing across the local region studied (SE Queensland), even on farms that do not use phosphine.

Implication 2

The mechanism of resistance provided by the rph2 locus has an exploitable metabolic weakness in that it provides hypersensitivity to a class of compounds that might be developed for use as synergists or structural treatments for resistance management.

Implication 3

It was found that the genes responsible for resistance are highly conserved in R. dominica and T. castaneum across continents. The significance of this finding is that the mechanisms for phosphine resistance are highly likely to be the same across all major grain storage regions. This means that resistance management strategies that address the mechanisms of resistance directly should be effective in all regions where phosphine resistance occurs.

Acknowledgements

The authors would like to acknowledge the support of the Australian Government’s Cooperative Research Centres Program. We would also like to acknowledge the contributions of the University of Queensland which contributed to two PhD scholarships and an Honours scholarship that contributed to this project.

The aim of this pilot project was to develop a statistical methodology for analysing the database so that insights into resistance development might be obtained.

Research outcomes:

The Australian phosphine resistance management strategy is underpinned by a national resistance monitoring program that provides continuous updates on the distribution and strength of resistance. This information is collected and stored in the Australian Grain Insect Resistance Database (AGIRD). This data warehouse now contains detailed information on the incidence of resistance in Australia for the past 20 years from thousands of sites monitored over this period.

The existence of AGIRD provides a unique opportunity for an analysis of the contribution of broader scale factors and practices to the occurrence of resistance that cannot be evaluated in local scale projects focussed on tactic development. However, the data in their current form are quite difficult to access and interrogate in a systematic way.

The aim of this pilot project was to develop a statistical methodology for analysing the database so that insights into resistance development might be obtained. We chose a limited set of the data from AGIRD with which to construct and test the methodology. The set chosen was detections of strong resistance to phosphine in all pest species over a 20 year period in Queensland. We analysed risk of resistance associated with factors such as storage type, site type, commodity, insect species, chemical treatment history and spatial-temporal elements.

Despite the limited geographical extent of the data analysis, the project demonstrated that very useful information relevant to improving resistance management strategies can be mined from AGIRD. For example, our analysis provided strong support for the implementation of resistance management tactics. The results demonstrate that the integrated use of alternative chemical treatments and physical methods such as grain cooling will significantly reduce the incidence of resistance.

Finally, this pilot project has demonstrated that the statistical methods developed could be used successfully to interrogate AGIRD. A whole database analysis is now feasible and this would allow much stronger trends and conclusions to be made. It would also allow for similarities and differences to be robustly identified for different regions of Australia and to determine whether the same biological and environmental factors, biosecurity practices and agricultural context are important. Also the modelling could be expanded to assess whether geographical movement of insects contributes to strong resistance.

Research implications:

Despite covering only a limited amount of data held in the AGIRD database, we are able to make a number of conclusions. Over the 20-year period, Strong Resistance (SR) was detected most frequently in the rusty grain beetle, Cryptolestes ferrugineus, (138 samples) followed by the lesser grain borer, Rhyzopertha dominica (46 samples), and much less frequently in the rice weevil, Sitophilus oryzae (9), red flour beetle, Tribolium castaneum (14) and sawtoothed grain beetle, Oryzaephilus surinamensis (10). SR occurred in storages with a history of phosphine use indicating that practices at particular storages are selecting for resistance rather than resistant insects invading from other locations.

Strong resistance in C. ferrugineus occurred most frequently in Central Queensland including the Emerald and Biloela districts (C), Kingaroy/South Burnett (SEB) and the region around Dalby (SEC) in storages not using fenitrothion. SR was not detected in storages using fenithrothion. Frequency of SR in this species was high in central storages and low on farm and at merchant premises, and higher in unsealed storages. As expected SR occurred in insects infesting commodities associated with the central handling system. This analysis revealed that incipient resistance was first detected in C. ferrugineus in 1992 and 1993 from single observations. There were then no detections of fully expressed strong resistance until 2007 and since that time detection rate has plateaued.

SR in R. dominica occurred in most regions but was a little more frequent in Burnett region. Detections were significantly less frequent in aerated and bunker storages. Use of pirimiphos-methyl was shown to be ineffective at controlling resistance in this species. Resistance was most frequent in central storages and on farm with relatively few detections from merchant premises. SR was first detected in this species in 1997 and there was a rapid increase in frequency to 1999 which was followed by a decline to 2004, another peak around 2010 and a recent decline.

Some conclusions could also be made about species with lower frequencies of SR. Strong resistance in O. surinamensis was highly associated with grain merchant premises and unsealed storages. Resistance in S. oryzae occurred in all sectors of the grain industry but was not detected on farm in Queensland. Use of fenitrothion appears to have prevented development of SR in T. castaneum as this resistance occurred only in storages where fenitrothion was not used and never where it was used.

Overall, it was clear from the results that each pest species must be considered individually when developing resistance management tactics as each can react in different ways to various treatments. As we improve our understanding of the biology and ecology of these insects we will be better able to target more effective management strategies.

Acknowledgements:

We thank Ms Hervoika Pavic and Dr Manoj Nayak for their assistance in preparation of the data for analysis.

Potato growing areas of Australia are currently considered free of Potato Spindle Tuber Viroid (PSTVd) and this pathogen is classified as an emergency plant pest (Category 3) under the Emergency Plant Pest Response Deed (EPPRD). There were six emergency responses for PSTVd in Western Australia (WA) and New South Wales (NSW) in the six years preceding commencement of this project and the concern was that without any pathway control there would continue to be periodic detections of PSTVd in the future. The importation of tomato seed, which until June 2008 was unregulated, had been implicated as the likely source of PSTVd. However, research at that time from Europe identified alternative hosts of PSTVd as potentially the source of inoculum for PSTVd infected tomatoes. Moreover, research then in WA indicated that both solanaceous and non-solanaceous species might be hosts.

Research outcomes:

This project has determined the extent of Potato spindle tuber viroid (PSTVd) infection in solanaceous and non-solanaceous weeds in Carnarvon, Western Australia; defined the genetic relationships between the strains of PSTVd that occur in Carnarvon and those found elsewhere in Australia; demonstrated how this pathogen is able to survive and spread on contaminated surfaces; revealed the pathogenicity of local PSTVd on potato and tomato plants; and provided key information to allow instigation of appropriate quarantine, disinfection and management protocols to prevent its further importation into and spread within Australia.

Research implications:

The horticultural industries in Australia now have been provided with a clearer understanding of the origins of the PSTVd outbreaks in Australia over recent years. Further, they have been provided with a better understanding of the dynamics of PSTVd epidemics in the field, the sources of infection, how contact transmission occurs, and how survival and infectivity is affected by different material surfaces. Measures that need to be taken at a national, state and industry level to minimise future spread the pathogen within Australia are now better defined (e.g. protocols to ensue seed is free of PSTVd contamination). The findings of this project have significantly advanced Australia’s capacity to safeguard its potato, tomato and other solanaceous plant-based industries. Ongoing work to highlight possible measures for disinfestation of contaminated materials will further enhance Australia’s border security while also helping to secure the future of valuable horticultural exports from Australia.

Acknowledgements:

Horticulture Australia Limited for matching funding, DAFWA for paying half salaries for Martin Barbetti and Roger Jones during this project.

The operation of export supply chains for agricultural and horticultural produce depends on compliance with the biosecurity standards set for export markets. This project used a systems based approach to analyse the optimal economic design of biosecurity management strategies based on biophysical, economic and market regulation factors.

Research outcomes:

The project developed two detailed biosecurity models, one for area wide management for Qfly in the Sunraysia Pest Free Area (PFA) and the other for Network Wide Management of stored grain pests in Western Australia. Both of these models can be used to address a wide range of biosecurity issues. Some examples are given below.

The results from the Qfly analysis shows the benefits of the current PFA and the optimal investment in surveillance. In terms of R&D it is possible to assess the upper bounds of returns to investment in improved border control, surveillance and eradication technology.

The stored grain analysis shows the costs of operating the grain supply network in the Kwinana zone and the costs to producers and the bulk handlers of closing sub-standard grain stores. The stored grain analysis shows that, in the absence of strong phosphine resistance, the cost of biosecurity lapses are relatively small so long as phosphine remains an effective fumigant.

Research implications:

• It is economically optimal to undertake surveillance on a grid of sentinel surveillance points spaced 830 m apart. This implies that the current surveillance schedule of one trap every 1000 m in production areas and one trap every 400 m in residential areas largely satisfies economic criteria in addition to the biosecurity criteria.
• Optimal surveillance does not vary significantly across the PFA.
• By far the greatest potential cost savings from R & D are to be realised from investments that reduce the cost of post-harvest treatments. This is because Qfly outbreaks are an intrinsic risk in the system, and that benefits of improved post-harvest treatment are realised over the whole of the FFEZ, rather than solely within the PFA.
• The cost of implementing AWM over the whole FFEZ region is more than offset by the post-harvest cost savings realised within the Sunraysia PFA, and confirms the findings of previous BCA of the Tri-State FFEZ strategy. However, there is significant risk of elevated incidence of Qfly outbreaks over decadal time scales, even in the absence of climate change, which will impact significantly on the profitability of the FFEZ scheme. To persist with AWM through these periods and to justify the public expense will likely be politically more difficult. However, even in the worst case scenarios the FFEZ scheme pays for itself, rather than incurring a net loss.

Implications for Grain NWM

• Contracts for grain delivery should have a clear incentive structure that rewards the delivery of insect free grain.
• Increasing the frequency of receival site monitoring or increasing its effectiveness through new technology to detect live insects and insect eggs is beneficial as it indirectly increases the level of biosecutiy effort on farm.
• Changes in the bulk handling network, for instance a receival site closure, should be assessed in terms of changes in producer profits and bulk handler costs. Thus if overall there is a gain in profit from altering the inventory of storage facilities then a change in those facilities should be considered.
• The current cost of infested grain not being detected until the port is relatively modest at a maximum of $1.5 million.

Acknowledgements:

• James Ridsdill-Smith
• DAFWA - Richard Johnston, Darryl Hardie, Rob Emery, Shashi Sharma, Francis De Lima, Bill Woods, Chris Newman, Maria deSousa-Majer, Mike Nunweek, Avril Russell-Brown
• I&I NSW - Kathryn Tobin, Richard Roger, Olga Ozols, Katina Lindhout, John Gould, Olivia Reynolds CBH - Ern Kostas, Graeme Smallman
• DSE Victoria - Emile Skender, Jaymie Norris BRS - Jodie Mewett, Rob Lesslie
• DPI Victoria – Gary D’Arcy, SallyAnn Harvey, Bill Fisher
• DEEDI QLD – Pat Collins
• BOM - Cathy Toby
• LPMA NSW – David Taylor
• CSIRO Entomology - Darren Kriticos, David Cook, Hazel Parry
• CRCNPB – Cain Roberts, Kirsty Bayliss
• QUT - Tony Clarke, Sama Low-Choy, Mark Stanaway, Solomon Balagawi, David Elmouttie
• UQ – Myron Zalucki
• UWA – Michael Renton, Mingren Shi, Juan Jose Garcia Adeva
• National University of Singapore - Roman Carrasco
• NEARMAP (for online image data)
• ABS (for online data).
• Industry groups (for data) - Citrus Australia, Murray Valley Citrus Board (MVCB), Australian Table Grape Association Inc (ATGA), Summer fruit Australia, HAL

Myrtle rust (eucalyptus/guava rust) caused by the fungus Puccinia psidii affects plants in the Myrtaceae family, which includes many Australian natives such as eucalypts, paperbark, bottlebrush, tea tree and lilly pilly. The disease is native to South America and was first described in 1884 in Brazil affecting guava, and more recently affecting eucalypt plantations (hence the common names guava and eucalyptus rust). P. psidii was identified as a ‘high to extreme risk’ biosecurity threat to Australia prior to its introduction here, due to the potential impacts on plant industries that rely on myrtaceous plants, and the significance of Myrtaceae in the Australian environment. A strain of Puccinia psidii (referred to as myrtle rust) was first detected on the central coast of New South Wales (NSW) in April 2010 and then quickly spread to Queensland (in December 2010) and Victoria (in December 2011), affecting more than 200 host species.

Research outcomes

This research into the epidemiology and host specificity of myrtle rust will:

• Help inform the development of disease forecasting systems to assist in fungicide management systems for plant industries reliant on species of Myrtaceae.
• Provide important baseline information to help gain an understanding of environments most threatened by myrtle rust allowing for development of strategic disease management programs.
• Provide information on the strain of P. psidii present in Australia, thus improving our capabilities to detect new strains of the rust.
• Provide information on host resistance mechanisms for the development of rapid resistance screening methods.
• Provide crucial data for more accurate predictive modelling systems for future monitoring and impact studies for states and territories where the disease has yet to spread, and other countries where myrtle rust has not yet been detected.
• Provide data for predicting impact levels in relation to future climate patterns within states of Australia already impacted by the disease.

Research implications 

The information and knowledge generated within this project provides the basis for other areas of research and development on this disease e.g. surveillance, population genetics, resistance breeding and monitoring impacts.

Acknowledgements

• Dr Gordon Guymer, Department of Science, Information Technology, Innovation and the Arts, Queensland
• CRCNPB
• New South Wales Government
• Queensland Government

This project looked at two aspects of the biology of lesser grain borer, dispersal ability and potential use of food sources other than stored grains.

Research outcomes:

We showed that fluorescent powders are effective for marking beetles used in field studies and that alternating colours are necessary to discriminate between beetles released at weekly intervals, as individuals from previous releases can persist in the local environment for 7-14 days. Recovery of marked beetles from pheromone traps 1 km from the release point was 1.4%, showing this pest has strong dispersal ability over open agricultural landscapes.

Host plant studies showed that lesser grain borers can develop on a range of other plants, however most native plants tested were either unsuitable or very poor hosts. The best alternative hosts were introduced ornamental species. Development of beetles on non-grain hosts takes longer and the adult beetles may also be smaller. So far no lesser grain borers have been recovered from field samples of plants known to support development of this pest in the laboratory.

Research implications:

If further data supports the theory that native plants are unsuitable or very poor hosts for lesser grain borers, and that introduced plant species are being used by lesser grain borers in the field, then there may be a real opportunity to reduce infestation risk in commercial storages through selective management of introduced plant species in the surrounding areas.

The results of this project demonstrate that lesser grain borers have strong dispersal capacity in Australian agricultural landscapes, with close parallels to the situation in the USA. The maximum dispersal distance remains unknown and there would be considerable merit in repeating the work over greater distances and also evaluating dispersal potential across more densely vegetated landscapes. Overseas studies suggest that the maximum dispersal distance for lesser grain borers may be 2-4km. If this holds true, then ensuring that major grain storages have no smaller on-farm storages within 4km would help to mitigate infestation risk, provided alternative food sources in the field are not acting as reservoirs for the beetles.

Acknowledgements:

The authors thank Tom Weir and Rolf Oberpreiler, Australian National Insect Collection, CSIRO, Canberra, for the identification of Coccotrypes carpophagus. Joe Valenzisi, Farm Manager, Yanco Agricultural Institute, and his staff are thanked for working around the large number of insect traps that have been set up all over the Institute. Bernie Dominiak and Laura Jiang, NSW DPI, provided the fluorescent marking powders used in the dispersal studies.

This project was developed to create a template to guide pest risk assessors through the steps to identify necessary adjustments to Pest Risk Analysis (PRA) to take account of climate change.

Research outcomes:

Pest Risk Analysis (PRA) is a formal process used by Biosecurity Australia to identify and assess the risk from pests and pathogens of concern to Australia. This project developed a template to guide pest risk assessors through the steps to identify necessary adjustments to PRA to take account of climate change. The template allows this to be done in a structured, repeatable and transparent manner. Completing the template for each PRA stage reveals whether risk has increased, decreased or remained unchanged. Accompanying this conclusion for each stage is a confidence score based on how much relevant data is available. This template is the first one developed that allows climate change to be factored into PRA.

Research implications:

Climate change is potentially going to cause significant changes to the arrival, establishment and spread of many pests and pathogens. Now that the template is available it will hopefully stimulate further work on this important problem.

The template will now ideally be applied to a range of quarantine pests and pathogens to establish how workable it is across a range of pest organisms. Results from wide application of the template may also prove useful by identifying common patterns of climate change influence. Another benefit from applying this template more widely would be to highlight where there is a particular lack of knowledge for elements of the PRA process or categories of pest.

Acknowledgements:

We would like to acknowledge the CRC Plant Biosecurity for supporting this project. Dr Ian Naumann from DAFF provided feedback on earlier versions of this document. We would also like to thank the following members of the QUADS working group for stimulating discussions and advice on how to incorporate climate change into analysis of pest risk: Karen Castro (Canadian Food Inspection Agency); Roger Magarey (North Carolina State University, USDA, APHIS) and Melanie Newfield (Ministry for Primary Industries, New Zealand).

Publications:

There are hundreds, perhaps thousands, of invasive species that have the potential to arrive and establish in any particular region or country. Identifying which species are more likely than others to arrive and establish is extremely difficult, yet the capacity to do so is vitally important to the biosecurity of a nation.

The aim of this project was to combine arrival likelihood with establishment likelihood to generate the invasion threat to Australia for 1,486 invasive fungal pathogens and insect pests, from all countries of the world.

Research outcomes

Arrival and establishment likelihood for Australia was estimated for 1,486 invasive insect pests and fungal plant pathogens. Arrival likelihood was estimated from the level of trade occurring between Australia and all other countries in millions of US$. Establishment likelihood was estimated by completing a SOM analysis of the worldwide distribution of the 1,486 invasive species. These two estimates were combined to generate a value for the invasion threat of all species in millions of US$. Considering all plant invasive species, China, USA and Japan poses the highest source of risk.

Research implications

Biosecurity agencies can use this information for further refinement of import risk assessments and inspection protocols. Further, the methodology presented here could be applied to any number of invasive species and the outputs generated be incorporated into any consultative process currently used to prioritise pest lists.

Acknowledgements

Thanks to CABI and Sue Worner for providing the CABI data and to Liam Thammavongsa for collating and editing the CABI and the IMF DOT data.

Stored grain is subject to major biosecurity problems which have the potential to significantly reduce the quality of the stored grain and to make it unsuitable for both domestic and international markets. The problems include attack by insect pests, rodents, birds and pathogens like fungi, as well as contamination by weed seeds, mycotoxins and pest faeces.

The Grain Storage and Biosecurity Training project was conducted to meet a need expressed by the grains storage industry for an accredited training program to ensure industry personnel managing the storage of bulk grain have the required knowledge and skills to protect and preserve stored grains to meet market demands. The training program developed has built on a Grain Quality Protection Course previously delivered by Charles Sturt University.

Research outcomes

Stored grain is subject to major biosecurity problems which have the potential to significantly reduce the quality of the stored grain and to make it unsuitable for both domestic and international markets. The problems include attack by insect pests, rodents, birds and pathogens like fungi, as well as contamination by weed seeds, mycotoxins and pest faeces.

The Grain Storage and Biosecurity Training project was conducted to meet a need expressed by the grains storage industry for an accredited training program to ensure industry personnel managing the storage of bulk grain have the required knowledge and skills to protect and preserve stored grains to meet market demands. The training program developed has built on a Grain Quality Protection Course previously delivered by Charles Sturt University.

The project entailed industry consultation, development of on-line training materials and assessments to maximise accessibility and flexibility, and conduct of a pilot course and workshop at Charles Sturt University, Wagga Wagga in March 2011.

On successful completion of the training and assessments participants are awarded a Statement of Attainment for the National Competency Standard: RTE4008A Maintain grain quality in storage. This will change to AHCBAC406A Maintain grain quality in storage when this comes into effect.

Ongoing delivery of the training program will be undertaken by Charles Sturt University’s School of Agricultural and Wine Sciences and CSU Training. 

Research implications

This professional development course is broadly aimed at middle level management/supervisors and operators involved principally in bulk-grain handling, grain merchandising, stock feeds manufacturing, brewing, milling, general rural merchandising, and grain storage. The course is also of relevance to grain transporters, advisers/consultants, marketers and re-sellers of grain protectants and fumigants.

Industry organisations and personnel, the community and policy makers will benefit in a number of ways:

• A more competent and adaptable workforce will lead to more cost-effective operations, greater competitiveness and higher profits for industry.
• Employees benefit in terms of potential for promotion, workplace satisfaction, employment and further education opportunities as well as a more professional approach to their duties.
• A skilled workforce will help protect the grains industry from biosecurity threats and assure domestic and international customers of the quality of Australian grain.

Acknowledgements

• Paul Weston, Project Officer, Charles Sturt University
• Jo Holloway, Research Entomologist, NSW Department Primary Industries
• Jo Slattery, Plant Health Australia
• Gerard McMullen, Consultant
• Jenny King, CSU Training
• Kamala Anggamuthu, CSU School of Agricultural and Wine Sciences
• Kirsty Bayliss, CRCNPB
• Chris Newman, Department of Agricultre and Food, WA
• David Jeffries, CBH
• Peter Botta, Department of Primary Industry, VIC
• Stephen Buick, Viterra
• Robin Reid, Graincorp Operations Ltd
• Stephen Dibley, Plant Health Australia

The recently completed CRCNPB funded project (CRC40135) “Improved Post Entry Quarantine Diagnostics” has developed a diagnostic protocol to detect at least 40 known and unknown potyvirus species (Zheng et al., 2010). The potyviruses are one of the most economically important plant virus groups with a wide geographical distribution and include several pathogens that are listed as biosecurity risks to Australian agricultural industries (e.g. Plum pox virus which poses a major threat to the stone fruit and almond industries).

Research outcomes

To ensure end user engagement by federal and state plant diagnostic laboratories in Australia and New Zealand, this protocol has been submitted to the Sub-committee for Plant health Diagnostic Standards (SPHDS) for ratification.

This is the first protocol for the detection of a group of target organisms (e.g. potyviruses) to be ratified by SPHDS and will be used at the border to test material for both known and unknown potyviruses. 

Research implications

It is envisaged that a SPHDS approved diagnostic protocol for potyvirus detection will demonstrate a degree of quality assurance to plant diagnostic laboratories in Australia and New Zealand that will facilitate the uptake and application of this diagnostic tool on a day-to-day basis.

Acknowledgements

The authors would like to thank Gerard Clover (MAF Biosecurity New Zealand), and Laurene Levy (USDA APHIS PPQ CPHST NPGBL, MD, USA) for trailing the degenerate primers for potyvirus detection in their labs. The Vic DPI and the CRCNPB supported the development of this diagnostic tool over the past five years.