Mite as well call Australia home – the immigration success story of the redlegged earth mite

 

Picture bean plant damaged by redlegged earth mite

Redlegged earth mite damage on a faba bean

By Adam Harper

Whenever communities emigrate from far away, they do their best to adapt and succeed in their new environment. Some groups succeed better than others. One population of Australian immigrants has been particularly good at adapting – the rather aptly named Halotydeus destructor, more commonly known as the redlegged earth mite (RLEM for short).

These pinhead-sized pests emigrated from South Africa in the early part of last century. They’ve settled into their new home so well that they are now the most expensive pest for Australian grain growers, at least in southern Australia, causing losses of about $45 million a year. An infestation is a triple threat – it can kill seedlings, reduce productivity and quality of older plants and lower the seed yield in spring. Pesticide treatment for RLEM costs about $20.5 million a year.

Picture of redlegged earth mite

The redlegged earth mite has adapted well to Australian conditions

Not only are they the most expensive pest, they are also showing resistance to some insecticides. What’s more, they’re expanding their range into climatic regions in Australia different from the ones they occupied in their native South Africa. We don’t yet know how far they are capable of extending their range. All these factors mean RLEM could spell disaster for grain growers. Fortunately University of Melbourne PhD student Matthew Hill recently completed his research on this problem.

In collaboration with his supervisors at The University of Melbourne and CSIRO, Matt found how the distribution of RLEM had changed in Australia and what this may mean for grain growers. He used historical data collected on RLEM to show how it is expanding its distribution. His research will help growers not affected by RLEM understand the risks RLEM could pose.

RLEM was first found in WA in 1917. By the 1920s it had spread to Victoria. Its ability to use a wide range of host plants (grain crops, pasture species, clover, and many broad-leaved weeds) meant that it spread easily and quickly. Matthew compiled three data sets, showing the recorded distribution of RLEM in its native South Africa, its invasive range in Australia in the 1960s, and its present-day range in Australia. He used these to develop models describing the environmental conditions this mite experienced in each case. His models show that RLEM has expanded beyond the range predicted by its distribution in South Africa. Today, RLEM can be found in hotter and drier inland regions of Australia.

Several factors may have helped RLEM expand into inland Australia. First, changing farming practices have meant a greater uptake of minimum or no tillage systems, as well as an increase in area under irrigation in the eastern states. Second, climate changes such as a small increase in winter rainfall may have also helped. Third, and perhaps most worryingly, RLEM may have undergone an adaptive genetic shift.

That means Australian RLEM populations may have different physiological traits that make them more tolerant to these new dry and hot environments. When Matthew compared mites from Australia and South Africa, the Australian mites were able to move around at higher temperatures than those from South Africa. Australian mites also recover more quickly from damaging cold temperatures. This shows that RLEM has adapted well to its new Australian home. However, the question still remains; how far is it capable of expanding its distribution?

Matt Hill gathering samples of mites in southern NSW

Matt Hill sampling mites from roadside vegetation in agricultural areas of southern NSW

Dr Garry McDonald at the University of Melbourne has been developing models that predict the risk of a RLEM outbreak each season, based on the weather patterns in a region. RLEMs are generally active in the cool, wet part of the year. Eggs laid in spring go into a suspended growth state over summer to protect them from drying out. Identifying the weather conditions that trigger egg hatching as the autumn weather cools is a crucial part of Garry’s models. Discovering these triggers will help growers more accurately predict when to watch out for RLEM. To discover exactly what the triggers are, Garry compiled data from various research trials conducted by state departments, CSIRO and universities over the past 50 years. He is now using this data to tease out the climate triggers for egg hatching. So far he has found that rainfall, then temperature, act in concert to regulate egg development and hatching.

Interestingly, the triggers in the western region appear to be different from those in the southern-eastern region. This supports some of Matthew’s findings that suggest there may be un-documented differences between populations in the western and southern-eastern regions. Once these triggers are validated across a range of sites, Garry can determine if they will be useful for growers currently managing RLEM, and whether different management strategies should be developed for the two regions.

Current research is aimed at giving growers advance notice of the risk or severity of an RLEM outbreak. However, to confidently predict outbreak risk, the factors that influence RLEM at both the regional and field levels need to be combined.

The work was funded by The University of Melbourne, CSIRO and the Grains Research and Development Corporation, and conducted as part of the National Invertebrate Pest Initiative.

For further information please contact Dr Nancy Schellhorn NIPI Leader nancy.schellhorn@csiro.au


Getting crazy ants under control

By Emily Lehmann

One of the world’s most invasive pests – the yellow crazy ant – is anything but a small problem in Australia’s top end.

Called ‘crazy’ for their erratic and frantic movements, these unwelcome critters were accidentally introduced into Australia and are a threat to native wildlife including other ant species.

Their capacity for destruction has been most devastatingly felt on Christmas Island where crazy ant supercolonies have formed and killed more than 20 million red crabs.

That’s why we have been leading efforts to control and eradicate the pest ant species across northern Australia.

We're keeping these crazy critters in check.
We’re keeping these crazy critters in check.

As part of this mission, we’ve helped local company Yolngu Business Enterprises (YBE2) join the effort by developing a new service in crazy ant control.

Operating in north-east Arnhem Land, YBE2 is contracted to undertake rehabilitation work at Rio Tinto Alcan’s Gove Bauxite mine. The Gove area is ridden with yellow crazy ants.

Crazy ant infestations pose a significant challenge to mining and effective rehabilitation, as digging up the earth risks spreading them. The site needs to be continually monitored and treated to clear it of any colonies.

Through the Researchers in Business program, our ant ecologist Dr Ben Hoffmann worked with the YBE2 team on the ground to develop protocols to monitor the land, and identify and collect data to accurately map ant infestations using a GPS system.

About 200 hectares of infested area was mapped by YBE2 staff and underwent treatment. Since the project ended, a further 200 hectares has been mapped for treatment later this year.

The team gained valuable data on the impact the ants and treatments have on the local environment, which could be used to improve YBE2’s rehabilitation processes.

This research and development has given YBE2 the capacity to monitor and capture data from the land, secured them a contract to control crazy ants on the mine site and will potentially open up new business opportunities.

It’s also putting a halt to the spread of yellow crazy ants, helping to protect the Australian environment.

Read more about our work with small and medium-sized businesses or our biosecurity research.


Avian influenza – why it’s not going away

Where do outbreaks of avian influenza come from? Image: Flickr/cskk

Where do outbreaks of avian influenza come from? Image: Flickr/cskk

By Frank Wong, Agent Characterisation Team Leader and Peter Daniels, Australian Animal Health Laboratory Assistant Director 

While Hong Kong has just reported its first case of the deadly H7N9 bird flu indicating that the virus may be spreading across China, Australia is reporting an egg shortage over Christmas as a result of the recent H7N2 cases in NSW. So how does the virus keep reinventing itself to cause issues across the world?

As over 70 per cent of emerging infectious diseases in people originate in animals, whenever we hear of a new virus outbreak we jump to find the source.

That’s not to vilify the animal species responsible, but to enable scientists to characterise the virus, track its path, assess its level of virulence and its potential impact on animal and human populations. While some recent viruses such as SARS and MERS have been tracked to bats, in the case of avian influenza in people, the source is birds.

Finding the source of influenza

As well as “bird flu” in the past there have also been reports of “swine flu”. In fact both these flu viruses belong to a group known as influenza A, and all influenza A viruses originally come from wild water fowl.

These complex viruses have evolved over time to become infectious to domestic birds such as farmed and back-yard poultry, pigs, horses, other domestic and wild animals and of course people. Cross-species transmissions can occur from time to time.

Viruses that infect more than one species frequently have natural hosts in which they replicate but do not cause obvious disease. The pathogen and host exist in harmony with each other and examples include Hendra, Nipah and SARS viruses in bats, Hanta viruses in rodents and influenza viruses in wild water birds.

On the whole, naturally occurring avian influenza (AI) viruses do not cause disease in wild bird populations. However, if wild water fowl are shedding virus and come in contact with domestic poultry, their food or water, either directly or via their excretions, AI can enter a poultry farm.

Once on a farm, the virus can be transmitted and maintained in the poultry in low pathogenic form, or certain strains can mutate to become highly pathogenic avian influenza (HPAI) in the new host with a high fatality rate.

In the case of farmed chickens, the close contact between these birds can lead to rapid transmission and in some countries infection has jumped from the poultry to other species such as pigs and humans.

Influenza virus evolution

There are a range of different influenza virus subtypes differentiated by the external proteins of the virus: haemagglutinin (H) and neuraminidase (N). It is generally recognised there are 16 different H types and 9 different N types.

Only some viruses of the H7 and H5 subtypes progress to be highly pathogenic in poultry through the process of mutation. Other H types may cause low-level disease but do not show the highly pathogenic mutations that can occur with H7 and H5 strains.

Avian influenza is an RNA virus with eight segments to its genome which makes it prone to re-assortment. When two or more influenza strains infect a host the genetic material can mix thereby producing a new strain or genotype. These genotypes can be tracked over time and the lineage identified for each of the genomic segments.

The major H7 virus lineages can be traced to either one of Europe and Asia (Eurasia), Australia, or Nth American origins. On this basis, gene sequencing of virus from an influenza outbreak can be used to determine whether it is likely to be an exotic strain newly introduced from another region, or derived from viruses already circulating in the local environment.

The Avian Influenza situation in Australia

While Australian water fowl remain predominantly local to our continent, there are many wild migratory birds such as shore birds and waders that travel across the world to share Australia’s waterways. A few of these migratory birds could potentially infect local wild water fowl.

The devastating H5N1 highly pathogenic avian influenza strain has not ever been detected in either Australian wild or domesticated birds. All previous highly pathogenic avian influenza outbreaks in Australian poultry have been caused by H7 viruses.

Low pathogenic viruses with an H7 haemagglutinin similar to that found in the current H7N2 outbreak and the earlier H7N7 outbreak in NSW have been detected in past unrelated samples from Australian wild water fowl.

Genetic tracking gives support to the belief that outbreaks such as the October 2013 H7N2 are the result of transmission of a low pathogenic virus from a wild bird reservoir to the poultry farm, where it then turned highly pathogenic as it spread among the farmed chickens.

Both the 2012 H7N7 and 2013 H7N2 are of Australian H7 lineage which has been circulating naturally here for many years.

Predictive genetic analysis

Genetic markers have been identified on H5 and H7 viruses that are associated with their potential to cause disease in people. The H7N9 virus in China in February 2013, though a low pathogenic avian virus, has certain genetic markers that are believed to be associated with its being more transmissible to and pathogenic in mammalian hosts.

Unlike the Chinese H7N9, the Australian H7N2 and H7N7 strains are more typical avian influenza A viruses that do not contain the same genetic markers that are a concern for disease in people.

The importance of biosecurity

Avian influenza will remain prevalent around the world so long as there are migratory birds. Biosecurity measures can mitigate the risk but whilst poultry, their food or water remain in potential contact with wild birds there remains a low possibility of the poultry becoming infected.

Biosecurity at the farm level is therefore vitally important to mitigate the risk of AI infection and biosecurity precautions to prevent disease outbreaks should be an everyday practice for all bird owners, whether large scale or back-yard poultry farmers.

This article was originally published at The Conversation. Read the original article.


Mega-pest worms its way into Brazil

Helicoverpa armigera_5

By Wee Tek Tay, Research Scientist, CSIRO Biosecurity Flagship

We often speak of the risks of new invasions in our increasingly interconnected world, and stress the need for a strong and reliable biosecurity system to safeguard our borders.

As global trading and markets increase, it’s essential to develop our ability to detect incursions using new and innovative surveillance techniques combined with rapid identification capabilities.  This is important because Incursions by exotic pests and diseases have the potential to seriously impact Australia’s people, agricultural industries and unique environment.

And right now, a team of Australian and international scientists are working closely with colleagues in Brazil as one of the most destructive pests known to agriculture – the cotton bollworm (Helicoverpa armigera) – worms its way into Brazilian agricultural fields.

Helicoverpa armigera has long been recognised as a serious biosecurity threat to the Americas, where it has the potential to establish across the South and North American continent with far greater anticipated potential economic loss to corn and cotton than the closely related Helicoverpa zea which is endemic to the Americas.

Incredibly, despite being intercepted at US Ports of Entry a staggering 4431 times since 1985, this mega-pest had not been previously reported to take hold on the American continents.

In Australia, Asia, Africa and Europe, where cotton bollworm is considered native, the damage it causes is estimated to cost $US 2 billion each year. In the last two growing seasons, high infestations of Helicoverpa species larvae were found in different regions of Brazil, resulting in substantial economic losses of up to 10 billion Brazilian Reals ($US 4.4 billion).

A cotton bollworm larvae decimating a cob of corn

A cotton bollworm larvae decimating a cob of corn

At first it was assumed that the damage was being caused by Helicoverpa zea, because the cotton bollworm had never previously been detected within the country. However, as the scale of spread and destruction was monitored, the Brazilian scientists knew that something was different and suspected that maybe the dreaded incursion of Helicoverpa armigera had indeed begun. At this point, Brazilian scientists from the Mato Grosso Cotton Institute approached CSIRO researchers to assist in the careful identification of the species attacking their crops.

Our scientists, together with French and Indian colleagues from CIRAD and IRD in France and the Indian Council of Agricultural Research used evolutionary and population genetics to confirm that the cotton bollworm has now successfully invaded Brazil.

Along with the confirmation that the Brazilians are indeed dealing with a new incursion of a serious exotic pest, the international team led by scientists from the CSIRO Biosecurity Flagship and Matto Grosso Cotton Institute is providing further vital data that will assist Brazil to manage this new menace.

The next steps for the research team are to investigate where the moth originated, where they are currently distributed, its spread across the South American continent, and the incidence of resistance to key pesticides. This information, coupled with CSIRO’s extensive expertise in insecticide resistance management will assist Brazil to develop effective strategies to manage this mega-pest.

You can read the full research paper at PLOS ONE.


For media enquiries contact Emma Pyers: +61 3 5227 5123, emma.pyers@csiro.au


Explainer: why Australia needs biosecurity

f you like good food, clean water, and protection from disease, you’re probably a fan of biosecurity. Image: AAP Julian Smith

If you like good food, clean water, and protection from disease, you’re probably a fan of biosecurity. Image: AAP Julian Smith

By Gary Fitt, Director, Biosecurity Flagship

When the Department of Agriculture called a halt to imports of pop star Katy Perry’s latest album this month, they weren’t making a musical judgement. They were protecting Australia’s biosecurity.

Biosecurity is also a process – a set of linked science based protocols and procedures aimed at stopping unwanted pests and diseases from arriving in Australia, detecting and rapidly eradicating them if they do arrive, or (if they become established) trying to minimise their impact by using long-term management strategies.

Perry’s album included a paper impregnated with seeds so listeners could grow their own plants; while well-meaning, those seeds could pose a biosecurity risk. That’s exactly the kind of risk that gets investigated in efforts to keep pests out of our country.

“Biosecurity” was first used to describe preventive and quarantine measures to reduce the risk of invasive pests or diseases arriving at a specific location that could damage crops and livestock as well as the wider environment.

Today, biosecurity can encompass much more. It includes managing biological threats to our people, industries or environment. These may be from exotic (foreign) or endemic organisms but they can also extend to pandemic diseases and the threat of bioterrorism.

A challenging environment

Australia’s island status protects us from exotic pests and diseases to a certain extent, but we also have an enormous border to protect. International trade is increasing, and ships, planes and people are moving in increasing volumes across international and state borders. This means there is more pressure than ever on our biosecurity surveillance and response systems.

Australia has an enviable biosecurity and quarantine system. But there is no such thing as zero risk.

Invasive alien species remain one of the greatest threats to our biodiversity, and our agricultural productivity. The reality is that exotic organisms arrive in Australia regularly and sometimes become established. A critical element of biosecurity response is to prioritise which ones are of most concern and need rapid response.

Biosecurity requires constant vigilance.

Biosecurity requires constant vigilance.

Animal biosecurity

Protecting our livestock industries, native wildlife, human health and the environment from exotic or emerging pests and diseases of animals is the realm of animal biosecurity.

Australia is fortunate to be free of many highly infectious animal diseases, such as foot and mouth disease, highly pathogenic forms of avian influenza, African swine fever and many others that have serious consequences in other countries. An outbreak of any of these diseases could significantly impact the productivity of our livestock industries, and make it very difficult to trade our agricultural products overseas, as well as result in significant social and economic costs.

The 2007 equine influenza (horse flu) outbreak in Australia was a “wake up call” of how disruptive exotic disease outbreaks can be and why vigilant biosecurity is so necessary.

Avian influenza has recently been detected on poultry farms in NSW (fortunately not the strains that can affect humans). The widespread culling that followed shows how much social and economic impact individual farmers might suffer if there are future disease outbreaks. Strict farm level biosecurity is becoming increasingly the norm across many industries.

Plant biosecurity

Plant pests and diseases can significantly damage Australia’s productive plant industries. They reduce yields, lower the quality of food, increase production costs and make it difficult to sell our produce in international markets.

This is true across the massive expanses of our wheat production, and in the more intensive high-value production of horticulture, wine, cotton and sugar industries.

Plant pests and diseases may also be a huge threat to our natural environment: native forests, grasslands, and shrub lands.

Again, Australia is lucky to be free of many damaging pests prevalent elsewhere in the world. Citrus greening is a disease of citrus we definitely don’t want, whilst the varroa mite, for example, has devastated honeybee productivity and pollination success in every continent except Australia.

Fewer pest and disease problems mean lower production costs. Areas where rigorous biosecurity can deliver “pest freedom” gives Australian producers an enormous advantage in international markets and allows us to have safer and cheaper locally produced food.

Biosecurity protects Australian farms' productivity.

Biosecurity protects Australian farms’ productivity.

Marine biosecurity

Australia has an enormous shoreline and amazing biodiversity in our marine ecosystems. Marine biosecurity is dedicated to keeping these systems intact. It focuses on protecting aquaculture, ports and the environment from problems caused by invasive marine organisms. These can threaten marine infrastructure and ecosystems.

Australia is in the midst of major port expansion; new ports are being developed and international shipping is increasing dramatically. As a result the risks from marine invasive species are growing and our biosecurity response needs to grow as well.

Human biosecurity

Many emerging infectious diseases in livestock that also affect human health emerge from wild, native species. These so-called zoonotic diseases make up 70% of all the emerging diseases affecting human populations and include the likes of avian influenza, SARS and Hendra virus. The impacts of these diseases can be extremely severe and the need to manage livestock and human health risks in a unified way is also becoming much clearer.

One Health” is a new way of looking at the connections between the environment, production animals and emerging threats to people. As with animal, plant and marine biosecurity, human biosecurity is about effective surveillance and response, being aware of the risks that are circulating the globe, having the tools to rapidly detect and diagnose them and the tools and systems to respond quickly.

Working together

Biosecurity is both a process and an outcome. A successful biosecurity system requires scientists, government, industry, and the community to cooperate. In the end it is a system of shared responsibility.

Australia is achieving this by working together across the continuum. We investigate risks offshore, focus on surveillance and detection at the border, and research effective response and management systems within our borders.

Robust emergency response arrangements are in place to manage outbreaks. But preventing pest, disease and weed incursions in the first place, through effective and smart surveillance, remains a national priority.

This article was originally published at The Conversation. Read the original article.


Putting a stop to the rot

Queensland Fruit Fly

The Queensland Fruit Fly

Flies aren’t only a nuisance for beach goers, some species can cause havoc for Australia’s agricultural industries and threaten the production and export opportunities of our fresh fruit and vegetable produce.

Queensland Fruit Fly (Q-fly) is one of these species. It’s the highest priority pest for a broad range of horticultural industries and can inflict significant costs on producers through management costs, lost production and reduced export opportunities, and on government and industries through eradication campaigns in areas where fruit fly does not regularly occur. These costs all eventually flow through to consumers and taxpayers.

An outbreak of Q-fly in a major fruit or vegetable production area, such as the Riverland in South Australia, has the potential to impact Australia’s export and domestic horticulture markets.

CSIRO’s Biosecurity Flagship together with Horticulture Australia Ltd, Plant & Food Research Australia and the Department of Primary Industries and Regions South Australia are joining forces to find a solution to this Q-fly problem.

Today marks the beginning of this partnership with the South Australian Premier Jay Weatherill announcing the establishment of a $3 million facility to breed male-only sterile Q-flies for use in Sterile Insect Technology (SIT) programs.

SIT is a scientifically proven method for suppressing or eradicating fruit fly populations and managing their potential impacts in horticulture production areas.

The $3 million State investment is in addition to a collaborative $15 million research and development consortium which will focus on new technologies to produce the male-only sterile Q-flies, and then the most effective release strategies and monitoring technologies needed to underpin effective area-wide control of Q-fly.

Boy biting into peach with blue sky in the background

Image: iStock

SIT approaches have already been used with great success around the world and in South Australia to combat Mediterranean fruit fly. However, the development of male-only sterile Q-fly will be a world first and will significantly enhance the cost effectiveness of SIT.

SIT is environmentally friendly and can be used in orchards, urban and environmentally sensitive areas, where application of conventional chemical treatments isn’t possible or is intrusive.


For media enquiries contact Emma Pyers: +61 3 5227 5123, emma.pyers@csiro.au


Defending ag from disease

Photo of the exterior of the Australian Animal Health Laboratory

The Australian Animal Health Laboratory in Geelong, Victoria

On-call 24 hours a day, seven days a week, diagnostic scientists at CSIRO are ready to respond should an emergency disease outbreak occur.

They could test 10,000 samples per day in an emergency, but as standard delivery, CSIRO scientists at Australian Animal Health Laboratory (AAHL) in Geelong, Victoria, test more than 45,000 samples for 55 terrestrial and 40 aquatic animal diseases every year.

Luckily, Australia is relatively free of many animal and human diseases found in other parts of the world, such as foot and mouth disease (FMD) and Nipah virus.

However, new infectious diseases, such as new strains of avian influenza, pose a constant threat to the health and wellbeing of animals and humans and pose a risk to Australia’s environment, industries and trade.

According to AAHL’s director Dr Kurt Zuelke, researchers are focused on reducing the threats of exotic and emerging animal diseases and, for example, are on standby with over 650 different tests covering a diverse range of animal species. “AAHL researches diseases of national importance found in livestock, aquaculture animals and wildlife, including those that can pass from animals to people,” Dr Zuelke said. “Our scientists are a front-line defence who help protect the country’s billion dollar livestock and aquaculture industries from disease threats on a daily basis.”

They play this defence role through performing diagnoses, establishing surveillance to monitor movements and emergences and if required, responding to animal disease emergencies. Better understanding diseases to develop diagnostic tests, vaccines and treatments is also crucial and CSIRO AAHL scientists lead the world on bat and insect-borne disease research. This is important for animal and human health as bats and insects are natural reserviours of a range of viruses and cause many of the world’s infectious diseases in both animals and humans.

Malaria and dengue, for example, are harmless to mosquitoes; blue tongue virus is harmless to midges; and Hendra, Nipah, and Severe Acute Respiratory Syndrome (SARS) viruses are harmless to bats – but all can be lethal to humans. AAHL also helps to train veterinarians in other countries to reduce the disease risks to Australia and is an official collaborating centre for capacity building in Southeast Asia. Recently, teams have visited Vietnam, Cambodia and Laos to train local veterinarians in disease diagnosis and testing techniques in their efforts to control and eradicate diseases such as FMD, classical swine fever and avian influenza. Importantly, this international work means Australia is more prepared with better threat assessments, surveillance and management options for many foreign diseases.


This article originally appeared in our 16 May Rural Press insert (pdf).

You can see what else we’ve been up to in our Rural Press Inserts Archive.


Australian agriculture’s biggest threat needs a global approach

Foot and mouth disease wreaks havoc on the economies of countries where it breaks out.

Foot and mouth disease wreaks havoc on the economies of countries where it breaks out.

By Wilna Vosloo, Principal investigator FMD risk management.

Co-authored by Dr Juan Lubroth, Chief Veterinary Officer, Food and Agriculture Organization of the United Nations (FAO).

Australia has been free of foot and mouth disease since 1872, but it is still considered the most serious biosecurity threat to Australia’s agricultural industries. A widespread outbreak could cost the economy more than A$16 billion in the first 12 months.

Can foot and mouth disease actually be controlled? We think so, and we can learn a lot from how rinderpest – a highly virulent cattle plague – was eradicated.

A model for eradication

Even before the 2011 global declaration of freedom from rinderpest by the United Nations, many were asking what animal disease we could focus on next. Rinderpest was only the second virus to be globally eradicated, after smallpox.

For centuries, rinderpest devastated cattle and buffalo populations in Europe, Asia, the Middle East and Africa. It led to the downfall of armies, caused rural famine and created inestimable hardship.

The disease was not restricted by national borders: international coordination was fundamental for managing, controlling and finally ridding the planet of the virus.

Rinderpest’s reintroduction into Europe led to the establishment of a coordinating authority, the World Organisation for Animal Health, in 1924. When the Food and Agriculture Organisation of the United Nations was created in 1945, their charter to improve food and nutrition across the globe could only be realised by fighting devastating livestock diseases such as rinderpest and foot and mouth disease.

The tools for managing foot and mouth disease can be used to bring other benefits.

The tools for managing foot and mouth disease can be used to bring other benefits.

After decades of research and significant investment, rinderpest was isolated to only a handful of geographical areas by the late 1990s. The last outbreak was reported in 2001.

The rinderpest success story makes it clear there are three things needed if you are to eradicate an animal disease. You need political will, veterinary and local knowledge about how the disease spreads, and adequate tools (such as diagnostic assays and quality vaccines) for intervention.

These factors apply to many animal diseases, so control does not need to focus on one disease alone. Investment in improved veterinary services, for example, doesn’t just apply to disease elimination; it benefits animal health, community livelihoods and a country’s whole economy.

Can we control and eliminate foot and mouth disease?

As with rinderpest, tackling foot and mouth disease needs a global approach. Recent outbreaks in previously disease-free countries show that a piecemeal approach isn’t working: we must control the disease at source, in the places where the virus is endemic.

But disease-free countries also have to invest in their neighbours’ efforts to control and eliminate the disease. Australia is investing in neighbouring countries such as Indonesia and the Philippines, helping them with control strategies, laboratory facilities, and staff training through CSIRO and AusAID. Those countries are now free of foot and mouth disease.

Once a country is free of foot and mouth disease it can take advantage of lucrative trade with other disease-free countries. This trade isn’t just in animals, milk and meat, but also in genetics. But it takes millions of dollars to maintain freedom from foot and mouth disease, and to keep those market opportunities – worth billions – open.

Meanwhile, resource-poor countries are devastated by the effects of foot and mouth disease: reduced milk quantity and quality, weight loss and severe lameness. They are further crippled by unploughed fields, inability to transport produce to market for sale and loss of available food and quality nutrients for humans.

Unfortunately, countries where such debilitating diseases are circulating usually also have competing priorities in other sectors such as human health, education, governance and maintaining civil and political stability.

We know we have the tools, the diagnostic ability and enough knowledge about disease transmission to take on foot and mouth disease. So, globally, can we tackle the threat in endemic settings head on?

Improving practises at farm level is a good first step

There is much work to be done. But rather than focusing specifically on eradicating foot and mouth disease, countries where the disease exists could start by improving on-farm biosecurity generally.

They should improve production practises and hygiene, thereby increasing efficiency in milk and meat production, and improving the way they manage natural resources.

This can spread benefits to other areas: child and maternal care, nutrition and hygiene for the farmers and communities around the world. Boosting veterinary services and information sharing provides better health care and builds trust with trading partners.

If we took this approach, we would certainly reduce the effect of production and trade-related diseases, as well as a multitude of diseases humans can get from animals and food. Such a holistic strategy would also increase access to quality drugs and veterinary vaccines across the myriad of microbial threats, and improve the availability of high quality nutritious foods.

It is therefore not possible to focus on only one disease when embarking on disease eradication or control. We need a global approach – targeted and tailored to the prevailing social and economic conditions – against those diseases that affect livelihoods, human health and global-to-local trade opportunities.

With significant effort and investment, control and eradication are possible – not just of foot and mouth disease, but of all high-impact diseases that threaten today’s and tomorrow’s world.

This article was originally published at The Conversation. Read the original article.


The turbulent times ahead for airborne pests

Boy on beach playing with sand

Image: Shutterstock

By Emma Pyers

Picture this – it’s a windy day in Northern Australia; in fact it’s a northerly wind. What are your initial thoughts?  Maybe heading to the beach with the family, hosting a BBQ or spending time outside with your canine friend?  But did you think about the risks these winds pose to our country’s biosecurity status?

If not, that’s OK because that’s what our scientists are here for – to help find solutions to protecting our environment and people from nasty pest and disease threats.

Currently the biggest biosecurity threat to Australia comes from the import of animals, plants, seeds and food that carry pests or pathogens.

So it makes sense that most of our surveillance effort goes into detecting these potential biosecurity threats at air and marine ports, and using our quarantine system for imported animals, although this still leaves open another ‘pathway’ for these nasties to use.

It’s on the wind.

It’s not as common as the direct import pathway, but it’s more concerning as it’s out of our immediate control.

So, we’re turning to mathematics and computer modelling to develop surveillance systems that can predict when and where pests and pathogens might be blown into, and from, Australia.

Yellow hot air balloon in the sky

Been hot air ballooning? Then you’ve experienced travelling with air layers and currents. Image: Zurijeta/Shutterstock

Traditionally wind trajectories have been used to show wind direction, but transport on the wind is more complex, as the pests and pathogens are also taken vertically.  The higher they are taken, the further they can travel.

Fortunately this is an area of great significance to atmospheric physicists, as they are interested in predicting things like how pollutants are dispersed in the air by chimneys, and how radiation might disperse following a nuclear accident.

This has led them to use a combination of mathematics and computer simulation to represent transport of particles in the atmosphere. There are now a number of computer applications that can do the hard work of combining the climate and weather data with the maths and physics of wind dispersion.

Infographic including maps detailing the dispersal of culicoides midges blowing into northern Australia

However, pest or pathogen dispersion is different to dust or pollutant dispersions, as living organisms respond differently within the atmosphere.  They might die if it’s too hot or cold, if the wind is too turbulent, or even if they’re susceptible to ultra-violet light.  All these organism-specific parameters need to be taken into account on top of standard dispersion modelling approaches to establish if there is a biosecurity risk or not.

It’s a challenge to bring these important elements together and make optimal decisions about when and where to do surveillance for wind-borne threats, even allowing for a high performance computer to analyse the data.

We’re working to solve this problem for all the relevant biosecurity domains interested in wind-borne spread, for example plant, animal and human health.

We are in the process of building a web-based tool that will link to the Bureau of Meteorology’s high-performance computing.  This new application is called the Tool for Assessing Pest or Pathogen Airborne Spread, also known as TAPPAS (sorry, it’s not Spanish cuisine). 

We expect TAPPAS to be ready for government, industry and research agencies interested in predicting and responding to airborne biosecurity threats for a ‘user acceptance testing” workshop in around 12-18 months time.

Our very own Peter Durr is presenting a talk on TAPPAS at the Biosecurity and Bioinvasion workshop tomorrow at CSIRO Discovery in Canberra.  CSIRO is co-hosting this event, which is part of the International Year of the Mathematics of Planet Earth, with AMSI, ANU and DAFF.


Maths at the zoo

By Carrie Bengston

You might not realise, but we use maths in nearly all of our daily activities. Every time we check the weather, use the internet or travel anywhere, maths plays a part. On a larger scale, maths can even be used to protect our flora and fauna from invasive pests. Our Biosecurity Flagship Director Dr Gary Fitt explains.

Zoos are a great place to visit but we don’t want Australia to become one. Image: Shutterstock.

Zoos are a great place to visit but we don’t want Australia to become one. Image: Shutterstock.

Q: You’ve said we don’t want Australia to become a zoo. What do you mean?

A:  Zoos have collections of animals from all around the world. While they’re fun to visit, we don’t want Australia to become one. Australia already has its own magnificent native flora and fauna. We’re an island continent and our wildlife really is unique in the world.

Take the Gouldian Finch for example. I’ve just spent a week in the Kimberley region of WA observing and counting these spectacularly colourful little birds. These endangered species are found nowhere else in the world but northern Australia. It would be tragic if they were lost from nature because of the introduction of a pest or disease.

With the world so connected by air and sea, the risks are real that Australia could become a zoo of introduced species alongside a reduced set of native ones.

It’s not just animals either – our plants are unique too. Botany Bay, where Captain James Cook landed, is named after the science of plants because so many unusual plant specimens were collected there by Joseph Banks. Unfortunately, our bushland today can become a new home for invasive plants, like the garden escapees lantana and privet.

Australia is home to some of the world's most unique and precious wildlife, just like the Gouldian Finch. Image: Cheryl Mares.

Australia is home to some of the world’s most unique and precious wildlife, just like the Gouldian Finch. Image: Cheryl Mares.

We don’t want invasive animals, plants or even micro-organisms from other parts of the world coming in and getting a foothold. Australia’s ecosystems would change forever, affecting health and agriculture. We need to protect our own biodiversity as much as we can. Our biosecurity research is key to that. It’s in our interests and future generations’ interests to get that right.

Q: You’ve enlisted mathematicians and statisticians to work on this research. What do they bring to the field of biosecurity?

Biosecurity is in a sense a game of probabilities. In this game the mathematical sciences are critical in two ways.

The first is to do with risk. Maths can help us determine the chances of a particular pest arriving and surviving in Australian environments, often in the face of uncertainties. By better understanding the risks and pathways, we can optimise investments in the right kind of surveillance systems. For instance, some of our projects quantify the riskiest pathways of entry in Australia, while others look at where to focus surveillance in ports.

The second is to do with response. Once a pest has arrived here, how do we get rid of it or limit its spread? We need to choose strategies that have the greatest chance of success. Once implemented, we need to know whether those methods are working.

Image: Cheryl Mares.

Maths and stats play a vital role in protecting Australia from invasive pests. Image: Cheryl Mares.

By making decisions based on statistical inference from the available data, rather than gut feel or vested interests, we can help policy makers and operational Biosecurity players better target funds for response. Maths is also important for modelling the life cycle stages of invasive species which might be most vulnerable to biological control.

Q: It’s Canberra’s centenary year. How has research in Canberra contributed to our understanding of bioinvasion and biosecurity?

A: Canberra is and has been home to some of Australia’s most famous research into invasive pests.

Canberra was where the ANU’s Frank Fenner worked on myxamatosis with CSIRO’s Ian Clunies-Ross and Macfarlane-Burnett. Mid-last century, they famously injected themselves with the myxoma virus, brought in to control the country’s rabbit plague, to prove it wouldn’t infect humans. 

For years, our work has played a vital role in controlling 'those pesky wabbits'.

For years, we’ve been helping to control ‘those pesky wabbits’.

The introduction of myxamotosis was a big step forward in controlling a pest that had devastated huge areas of farmland and was costing millions in lost production. We’re continuing our work here to improve the effectiveness of the next generation rabbit biocontrol agent, calicivirus.

***

September 12 – 13 is the Biosecurity and Bioinvasion workshop in Canberra. Our experts are discussing how maths is essential in protecting Australia from the threat of pests and diseases as part of the International Year of the Maths of Planet Earth.


Emerging tech creating a safer food chain

iStock_000021161362XLarge

By Mala Gamage and Kai Knoerzer

In recent years a number of emerging or new food processing technologies have been investigated, developed and to some extent implemented, with the aim of improving or replacing conventional processing technologies.

By reducing pathogens and invasive species from food products, these technologies have great potential for the treatment of products exported interstate or overseas, opening the doors for wider export markets.

Because they take advantage of different applications and gentler processing methods, they also often result in processed food with a ‘fresh-like’ quality.

And while they all use vastly different techniques, they’re all pretty impressive.

Photo of sesame seeds being subjected to cool plasma

Are these sesame seeds cooler now after a dose of plasma?

Cool plasma

Cool plasma isn’t only cool in temperature, it’s cool science.

Plasma is also known as the fourth state of matter (as well as solid, liquid and gas) and exists when the internal energy of a gas is increased to a state where the gas molecules become ionised.  This plasma phase contains a number of reactive species, such as ions, free radicals and also UV radiation, which are all effective in killing bacteria, fungal spores and insects, and can be used to inactivate pests on the product surface.

Photo of a Pilot-scale continuous, pentagonal Microwave tunnel

A continuous pentagonal microwave tunnel (including convection heating facilities) at our Food Manufacturing pilot plant in Werribee, Victoria.

Microwave Processing

Large scale microwaves are actually very similar to the microwave ovens most of us have at home, but usually have a higher power capacity, and conveying systems to transport products through a microwave tunnel, where they are heated with an electromagnetic field.

Microwave processing has recently been used to disinfest (inactivate insect pests) fresh food such as apples, capsicums, zucchinis and avocados, while maintaining the quality and freshness of the product.

The microwave technology also has great potential for the disinfestation of grains.

The effect of high pressure on bugs

The effect of high pressure on bugs

High Pressure Processing

Imagine 200 elephants, each weighing three tons, standing on a piston the size of a CD. That’s greater pressure than at the deepest point of the ocean, and is the amount of pressure that products face during High Pressure Processing (HPP).

The products are packed into tight vessels and subjected to pressures up to 600 MPa, or 6000 bars.

And while you might think that would crush the products, they actually only compress by about 20 per cent, although that’s enough to kill any bacteria and insects present.

And by the end of the process, the product usually finishes at the same size it started.

Photo of a collapsing cavitation bubble

A collapsing cavitation bubble

Ultrasound

Ultrasound is nothing but sound, but at a frequency so high that it can’t be heard by people.

It’s generated by vibrating plates (at 20,000 vibrations per second or higher) which leads to the formation of water vapour bubbles, called cavitation bubbles.

Once they exceed a certain size the bubbles violently collapse, creating very high pressures, temperatures and streaming. These harsh conditions can be used to get rid of pests from product surfaces, as well as cracks and crevices.

A schematic representation of electrons activating on the surface of pecan nuts. Or...pecan nuts covered with a lot of e-'s

A schematic representation of electrons activating on the surface of pecan nuts. Or…pecan nuts covered with a lot of ‘e-‘s

Low Energy Electron Beams

Electron beams inactivate bacteria, spores, fungi and insects through ionisation of the molecules in the pest.

The technology is actually very similar to the old, bulky tube TVs, where electrons are released from a hot electrode and accelerated and guided by magnetic fields onto the TV screen. Instead of the TV screen, the electron beam is guided onto the surface of a product.

Similar to cool plasma, it’s mainly effective on product surfaces, but can also penetrate to depths up to 1mm.

The technology is gaining traction in Germany for the organic treatment of grain seeds, where it completely inactivates pests without negatively affecting germination of the seeds.


About the Authors

Photo of Mala GamageDr Mala Gamage, Research Project Leader, CSIRO Animal, Food and Health Sciences

Mala has initiated research on the identification of innovative technological solutions for insect disinfestation in horticultural commodities, and evaluated the feasibility of using ultrasound, high pressure and microwave for the disinfestation of fruit flies.


Kai KnoerzerDr Kai Knoerzer, Research Project Leader, CSIRO Animal, Food and Health Sciences

Kai is working to enhance the nutritional value, convenience and quality attributes (such as fresh taste, colour etc) of processed foods through innovative food processing technologies, including high pressure, pulsed electric fields, microwave, ultrasound, and cool plasma processing.


Have Australia’s native plants dodged a rusty bullet?

It doesn't just happen to old metals - plants can get rusty too. Image: Louise Morin

It doesn’t just happen to old metal – plants can get rusty too. Image: Louise Morin.

By Mary-Lou Considine

It was the disease Australian plant biologists had been waiting for. In April 2010, myrtle rust – a type of fungus that was threatening eucalypt plantations overseas – found its way on to a native plant in New South Wales.

Environmentalists predicted that if the rust spread, Australia’s landscape would become a mycological firestorm. But three years on biologists are asking, has it been more of a fungal fizzle?

Given the right conditions, myrtle rust could infect many Australian native trees within the myrtle family. When the rust infects a plant, bright yellow lesions appear causing the leaves to twist and die.

Since myrtles account for ten per cent of Australia’s total plant species, it’s no wonder the appearance of the fungus in 2010 was seen as a potential disaster.

But while the pathogen’s reach across the myrtle family is broad, it hasn’t created the widespread devastation as predicted. Our Ecosystem Science experts explain why.

Unfortunately it’s not all good news. With our changing climate and increased global trade, introduced diseases and pests are on the rise. Thankfully our new Biosecurity Flagship is putting these threats under the microscope to help protect the health of our environment and people.

Read the full story in the latest edition of ECOS Magazine.


Preventing a pathway for pathogens

Part of the Biosecurity Series

By guest blogger Professor Peter Doherty

Photo of the tail of three planes

Image: caribb/Flickr

It’s no big secret that we’re citizens of an increasingly globalized planet where ideas, information, goods and services get around very fast. One of the downsides of this brave new world is that the same is true for pests and pathogens.

The security services, customs officers and quarantine regulations/officials protect Australia from such invasions as much as possible, although given the volume of trade and human movement, stopping bad things at the borders can only be part of any effective strategy.

There’s also a need for continual environmental monitoring to make sure that nothing dangerous slips through which could compromise Australia’s agricultural industries, wildlife and natural environments.

When it comes to biodefence against invading viruses, bacteria, insects, plants, marine parasites (on the hulls of ships) and so forth, we have layers of operation that function both at the Federal and State level.

This is, of course, where the wonderful high security CSIRO Australian Animal Health Laboratory (AAHL) comes into its own, providing the essential diagnostic tools and facilities for safe studies of deadly viruses in animals that are unique to the South-east Asian region.

Photo of the exterior of the Australian Animal Health Laboratory

The Australian Animal Health Laboratory in Geelong, Victoria

Apart from its service to the veterinary world, AAHL has also pioneered studies of bat-borne viruses like Hendra and Nipah (active to the North-West of Australia) that can transmit to people from infected horses and pigs respectively. These are classic cases of the “One Health” view CSIRO takes that stresses the intimate interplay between animal disease and human disease. Apart from the Henipaviruses, AAHL also has the facilities that allow CSIRO researchers to study the avian influenza A viruses, that are a looming threat to both domestic poultry and people.

An artificially coloured electron micrograph of the new-SARS like virus – now known as the Middle East Respiratory Syndrome (MERS) – which has caused an ongoing outbreak of respiratory disease and has spread from the Middle East to the United Kingdom, Germany, France, Italy and Tunisia.

An artificially coloured electron micrograph of the new-SARS like virus – now known as the Middle East Respiratory Syndrome (MERS) – which has caused an ongoing outbreak of respiratory disease and has spread from the Middle East to the United Kingdom, Germany, France, Italy and Tunisia. (click for full size image)

The new CSIRO Biosecurity Flagship pulls together research capability from across CSIRO together with a broad range of collaborating centres and groups. Sharing information is vital for such activities.  Clearly, Australia cannot afford to have “silos” and artificial barriers that in any sense compromise our biological security. Of ongoing concern are the hi-path variants of the avian influenza H5N1 viruses that continue to circulate in wild and domestic birds (and occasionally infect and kill people) in the countries to the north-west of Australia. While we’ve avoided that particular threat so far, the situation requires constant monitoring.

Another threat is the recently emerged H7N9 avian influenza virus and MERS, a novel coronavirus in the Middle East.

I’ve said nothing about plant, insect and fish pathogens, but there are many diseases of key species, such as bees, trout and salmon that we have so far managed to keep at bay.

The new CSIRO Biosecurity Flagship is a great step in the right direction, and we need to continue doing all that we possibly can to ensure the long-term health and wellbeing of all the life forms that inhabit our extraordinary and unique country.

Join the Conversation: #bflaunch


About the Author

Photo of Peter Doherty

Peter Doherty trained initially as a veterinarian and shared the 1996 Nobel Prize for Physiology or Medicine for discoveries concerning our immune defence against viruses. He published the non-fiction book “Sentinel Chickens: What Birds Tell Us About our Health and our World” in 2012, and his new book “Pandemics: What Everyone Needs to Know” will be available in Australia from October.

Follow Peter on twitter: @ProfPCDoherty


Controlling ‘those pesky wabbits’ on land and in water

Part of the Biosecurity Series

By Michelle Beltrame, Ken McColl and Tanja Strive

‘Shhh. Be vewy vewy quiet, we’re wesearching viruses’.

If Elmer Fudd is the arch-enemy of Bugs Bunny, then it’s safe to say that we’re not only the arch-enemy of the European rabbit, but the fish known as the ‘rabbit of the waterways’ – the European carp.

We’re arming ourselves with viruses with the aim of keeping these two invasive species in check and to help protect Australia’s economy and environment. This strategy is called biological control (‘biocontrol’ for short) – using disease to tackle invasive pests.

The battle of the rabbit

Black and white photo of rabbits clustering around a small waterhole

This photo was taken under controlled conditions during myxoma virus trials on Wardang Island off South Australia in 1938 (click for full size image). Photo: M W Mules/CSIRO.

The European rabbit is a serious threat to agriculture and biodiversity in Australia. Myxoma virus, released in 1950 and Rabbit Calicivirus Disease (RCD), released in 1996, have proven the only effective means to significantly reduce rabbit numbers. The benefits to the agricultural industries of these two biocontrol viruses are estimated at $70 billion.

The European rabbit was brought to Australia onboard the First Fleet in 1788, but only became a major pest in 1859 when 24 wild rabbits were released by a wealthy Victorian grazier keen on the sport of hunting, and, …well… they bred like wild rabbits! Soon millions of rabbits were competing with Australia’s livestock for feed and were damaging the environment and threatening our native animals.

Our predecessor, CSIR, conducted initial trials of myxomatosis that ultimately resulted in the release of the virus in 1950. It was the world’s first successful biocontrol program of a mammalian pest, taming a scourge that had threatened Australian agriculture and environment.

Lionel Bull, Chief of the CSIR Division of Animal Health and Nutition, releasing the first infected rabbits as part of the myxoma virus trial. (click for full size image)

Lionel Bull, Chief of the CSIR Division of Animal Health and Nutition, releasing the first infected rabbits as part of the myxoma virus trial. (click for full size image)

The initial release of myxoma virus led to a dramatic reduction of Australia’s rabbit population – killing 99.8 per cent of rabbits that caught the infection in some areas. Because the virus is spread by mosquitoes, it had its greatest impact in the highest rainfall areas but didn’t work as well in arid zones where mosquitoes can’t survive.

By the late 1950s, resistance to the myxoma virus was starting to build up in Australia’s rabbits. The virus became less effective and rabbit numbers increased, but not to pre-1950 levels.

RDC was first discovered in China in 1984 and soon after in other countries in Asia, Europe and in Mexico. The viral disease affects only European rabbits, and its discovery offshore alerted scientists to a potential new biocontrol for wild rabbits in Australia.

The introduction of calicivirus in Australia in 1996 again reduced rabbit numbers drastically, but it had greater impact in the arid zones and least impact in the higher rainfall areas. A few years ago we discovered that Australian rabbits in the higher rainfall areas actually carry a native calicivirus that may provide some immunity to the disease. This benign form of the virus is very similar, so we suspect it’s acting as an imperfect natural vaccine against the more virulent strain.

Calicivirus and myxomatosis are still having an impact, but over the years their effectiveness has declined. As a result, we’re currently researching different caliciviruses in Australian wild rabbits, and their interactions with RCD to help determine potential future implementations for rabbit biocontrol.

Curbing our carp numbers

Photo of carp jumping out of water

A European Carp. Image: Dirk-Jan Kraan/Flickr

Carp is a pest associated with the poor health of our rivers and wetlands. The fish was first introduced to Australia more than 100 years ago and is now rampant in the Murray-Darling Basin.

Image: sophietica/Flickr.

Koi Carp. Image: sophietica/Flickr.

We’re currently investigating a disease called cyprinid herpesvirus-3, also known as koi herpesvirus (or KHV), as a potential new biocontrol agent to help eradicate carp from Australia. The virus first appeared in Israel in 1998, and spread rapidly throughout much of the world, although not to Australia or New Zealand. It causes high death rates in common carp and in the ornamental variety of carp known as koi carp. No other species of fish, including goldfish, are known to be affected by it.

We’re conducting our research within the world’s most sophisticated high containment facility within the CSIRO-Australian Animal Health Laboratory (AAHL), where we’re undertaking rigorous tests to determine the virus’ suitability for controlling carp.

We’ve identified that CyHV-3 does kill Australian carp, and it kills them quickly, and current research has shown that the virus doesn’t affect native Australian or any other introduced species of fish.

Over the next few years we’ll continue to test the susceptibility of other fish species to CyHV-3 and address questions regarding the safety of possible widespread distribution of the virus, both for humans and for other animal species

Join the Conversation: #bflaunch


About the Authors

Photo of Ken MccollDr Ken McColl, Research Scientist at CSIRO’s Australian Animal Health Laboratory, Geelong.

Ken is a veterinary virologist and pathologist specialising in the research and diagnosis of diseases of aquatic animals. For the past few years, Dr McColl’s major interest has centred on the possible use of koi herpesvirus (KHV) as a biological control agent for carp in Australia.


Photo of Tanja StriveDr Tanja Strive, Research Team Leader, CSIRO Ecosystem Sciences.

Tanja is a molecular virologist, and her current research focuses on various aspects of the biological control of vertebrate pest species, in particular rabbits. Key projects investigate: a) the interactions of different co-occurring rabbit pathogens in the field and the implications for rabbit control, b) the molecular virulence mechanisms of rabbit calicivirus, c) the selection of suitable virus strains for successive and ongoing field releases, and d) The evolution of rabbit caliciviruses as a model system for emerging diseases.


Battling pests by the numbers

Biosecurity Series

By Simon Barry

Image: Freedigitalphotos.net

Image: Freedigitalphotos.net

Effective biosecurity protects Australia’s environment and industries, but managing risk is an uncertain business. That’s why we need statistics.

Australia’s physical isolation has fostered the development of an amazing diversity of unique plants and animals, and has protected us from many serious pests and diseases that circulate around the world.

But we’re also a nation of traders — our prosperity is built on the import and export of goods and services.

With trade, however, can come exotic pests and diseases that have significant impacts on agriculture, the environment and economy.

In Australia’s history, a number of iconic examples are etched in the national psyche.

Rabbits were introduced into Australia several times, beginning with the First Fleet in 1788.  Once established, they multiplied rapidly reaching plague proportions last century.  They, in combination with introduced red fox and feral cat populations they support, are suspected of being the main cause of species loss in Australia.

The cactus prickly pear (Opuntia sp.) was introduced to Australia to start a cochineal dye industry.  It spread quickly and at its height infested 24 million hectares of farmland with severe impacts on our agriculture.

A prickly pear site before treatment with Cactoblastis cactorum (click for a comparison of before and after)

A prickly pear site before treatment with Cactoblastis cactorum (View a comparison of before and after)

While the community narrative is often framed around fear of invasion and potentially catastrophic consequences, the policy challenges are more complex and diffuse.

Decision makers need to assess risks of importation of different goods and materials against their possible benefits.  They need to design surveillance systems to manage unacceptable risks; to certify that our exports are pest free; to predict their spread and impact when incursions of pests occur.

All of this is done against a backdrop of uncertainty.

Which species will successfully establish can be difficult to predict – impacts of exotic pests in agricultural systems may be predictable in some circumstances, but their environmental impacts are more uncertain.  The linkage between biosecurity, trade and market access means that stakeholders may have a vested interest in the process. And the data required to predict accurately how successfully pest species establish here are limited or in most cases thankfully non-existent, so secondary sources, such as observations in other countries need to be used.

This is where statistics helps inform our decisions.

Statistics deals naturally with uncertainty and explicitly considers one of the most fundamental scientific questions: What can we logically infer about the world based on limited data?

It can support the development of established methodologies, such as assessing biological control agents, but it also opens up the possibility of using other existing and new data streams such as citizen-science collected data and genomics.

When these are combined with new algorithms and high performance computing, a range of exciting new opportunities arise that mean we’re better placed to tackle these issues than ever before.

For example, we are using these new computational informatics approaches to analyse whether or not red foxes have been eradicated in Tasmania.

Photo of red fox

European red fox (Vulpes vulpes). Image: Liz Poon/CSIRO

Hard data is limited to a handful of fox carcasses discovered by members of the public, some footprints, a skull, DNA extracted from fox scats (poo) and blood found at the site of a chook pen raid from an unsighted predator.

As of 2010, the distribution of fox DNA-positive scats suggested a widespread fox population.

We’ve analysed the fox sighting data using a new statistical method known as approximate Bayesian computation, which uses computers to simulate millions of different plausible scenarios for the introduction and growth of the fox population.

Our analysis of the data up until 2013 provides different conclusions — that the introduced fox population is most likely extinct, or small and probably demographically weak.

Rather than worry us, the conflict between this result and the analysis based on scats is a healthy one and will drive research efforts to reconcile these differences.

We’re also using statistic to monitor the risk of pests and diseases which threaten Australia’s honeybee industry and many horticultural industries that rely on bees for pollination.

Australia is one of the only countries free of the mite Varroa destructor.  Varroa has had a huge impact on global beekeeping as bee populations overseas have been decimated. Thankfully, it has yet to reach Australia and here is a need for early detection so that eradication could begin.

A European honey bee prepupa with varroa mites

A European honey bee prepupa with varroa mites

We are using shipping data from the Lloyds registry and interception data on exotic bees and bee pests from Australian quarantine officers to resolve the relative risk of different overseas locations and the reduction of this risk due to journey duration.

Effective biosecurity will continue to be important in maintaining the efficiency of Australian agricultural industries and to protect the environment.

These two examples demonstrate how mathematical and statistical sciences play a key role and Australia is well placed to innovate in this area.

Join the Conversation: #bflaunch

We’re hosting  A Planet at Risk: Bioinvasion and Biosecurity workshop in Canberra in September. Visit the website for more details.


About the Author

Photo of Simon BarryDr Simon Barry is Program Leader of Environmental Informatics, CSIRO Biosecurity Flagship.

Simon uses his expertise in modelling and monitoring methodologies to lead research projects with the aim of helping environmental resource managers and stakeholders understand what resources we have, their quality and how to manage them for sustainability.


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