Natural Resources Management Biosecurity Unit

Adelaide, Australia

Natural Resources Management Biosecurity Unit

Adelaide, Australia
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Liu J.,CSIRO | Liu J.,University of Canberra | Fordham D.A.,University of Adelaide | Cooke B.D.,University of Canberra | And 5 more authors.
PLoS ONE | Year: 2014

Background: Australia relies heavily on rabbit haemorrhagic disease virus (RHDV) for the biological control of introduced European wild rabbits Oryctolagus cuniculus, which are significant economic and environmental pests. An endemic non-pathogenic rabbit calicivirus termed RCV-A1 also occurs in wild rabbits in Australian and provides partial protection against lethal RHDV infection, thus interfering with effective rabbit control. Despite its obvious importance for rabbit population management, little is known about the epidemiology of this benign rabbit calicivirus. Methods: We determined the continent-wide distribution and prevalence of RCV-A1 by analysing 1,805 serum samples from wild rabbit populations at 78 sites across Australia for the presence of antibodies to RCV-A1 using a serological test that specifically detects RCV-A1 antibodies and does not cross-react with co-occurring RHDV antibodies. We also investigated possible correlation between climate variables and prevalence of RCV-A1 by using generalised linear mixed effect models. Results: Antibodies to RCV-A1 were predominantly detected in rabbit populations in cool, high rainfall areas of the south-east and south-west of the continent. There was strong support for modelling RCV-A1 prevalence as a function of average annual rainfall and minimum temperature. The best ranked model explained 26% of the model structural deviance. According to this model, distribution and prevalence of RCV-A1 is positively correlated with periods of above average rainfall and negatively correlated with periods of drought. Implications: Our statistical model of RCV-A1 prevalence will greatly increase our understanding of RCV-A1 epidemiology and its interaction with RHDV in Australia. By defining the environmental conditions associated with the prevalence of RCV-A1, it also contributes towards understanding the distribution of similar viruses in New Zealand and Europe. © 2014 Liu et al.


Fordham D.A.,University of Adelaide | Sinclair R.G.,Natural Resources Management Biosecurity Unit | Peacock D.E.,Natural Resources Management Biosecurity Unit | Mutze G.J.,Natural Resources Management Biosecurity Unit | And 4 more authors.
Austral Ecology | Year: 2012

The European rabbit, Oryctolagus cuniculus, is threatened within its native range, yet it is a highly successful colonizing pest species across its worldwide introduced range, causing large economic losses and widespread environmental degradation. To date, there has been no long-term empirical evidence documenting the relative roles of climatic, epidemiological and biological factors in limiting life-history determinants of rabbit range and abundance. Using 12years of capture-mark-recapture data from their exotic range in Australia, we constructed candidate Cormack-Jolly-Seber models to test the influence of environmental, competition and disease conditions on rabbit survival and recruitment. Our results show that: (i) population-level disease infection rate has the largest overall impact on rabbit survival, explaining 80% of variance in survival rates; (ii) environmental as well as epidemiological conditions constrain rabbit survival, especially for younger animals; (iii) temporal variation in rabbit kitten recruitment patterns are best described by a combination of climate, competition and disease settings (accounting for 68% of variance), while temperature alone has a strong negative influence on kitten recruitment; and (iv) recruitment responds positively to rabbit haemorrhagic disease, but negatively to myxomatosis - the former, probably being mediated through a disease driven effect on intraspecific competition for food. A strengthened understanding of climate change impacts on rabbit range and abundance can be achieved by accounting explicitly for potential synergisms between disease dynamics and climate. In this analysis, we provide the first step towards such an attempt for this important mammal species. Integrated approaches of this kind are essential for future forecasts of rabbit range and abundance, offsetting the conservation threat faced by O.cuniculus in its native range, and achieving effective management in exotic habitats. © 2012 The Authors. Austral Ecology © 2012 Ecological Society of Australia.


PubMed | Natural Resources Management Biosecurity Unit, University of Adelaide, University of Canberra and CSIRO
Type: Journal Article | Journal: PloS one | Year: 2014

Australia relies heavily on rabbit haemorrhagic disease virus (RHDV) for the biological control of introduced European wild rabbits Oryctolagus cuniculus, which are significant economic and environmental pests. An endemic non-pathogenic rabbit calicivirus termed RCV-A1 also occurs in wild rabbits in Australian and provides partial protection against lethal RHDV infection, thus interfering with effective rabbit control. Despite its obvious importance for rabbit population management, little is known about the epidemiology of this benign rabbit calicivirus.We determined the continent-wide distribution and prevalence of RCV-A1 by analysing 1,805 serum samples from wild rabbit populations at 78 sites across Australia for the presence of antibodies to RCV-A1 using a serological test that specifically detects RCV-A1 antibodies and does not cross-react with co-occurring RHDV antibodies. We also investigated possible correlation between climate variables and prevalence of RCV-A1 by using generalised linear mixed effect models.Antibodies to RCV-A1 were predominantly detected in rabbit populations in cool, high rainfall areas of the south-east and south-west of the continent. There was strong support for modelling RCV-A1 prevalence as a function of average annual rainfall and minimum temperature. The best ranked model explained 26% of the model structural deviance. According to this model, distribution and prevalence of RCV-A1 is positively correlated with periods of above average rainfall and negatively correlated with periods of drought.Our statistical model of RCV-A1 prevalence will greatly increase our understanding of RCV-A1 epidemiology and its interaction with RHDV in Australia. By defining the environmental conditions associated with the prevalence of RCV-A1, it also contributes towards understanding the distribution of similar viruses in New Zealand and Europe.


Elsworth P.G.,University of Canberra | Elsworth P.G.,Robert Wicks Pest Animal Research Center | Kovaliski J.,Natural Resources Management Biosecurity Unit | Cooke B.D.,University of Canberra
Epidemiology and Infection | Year: 2012

Rabbit haemorrhagic disease is a major tool for the management of introduced, wild rabbits in Australia. However, new evidence suggests that rabbits may be developing resistance to the disease. Rabbits sourced from wild populations in central and southeastern Australia, and domestic rabbits for comparison, were experimentally challenged with a low 60 ID50 oral dose of commercially available Czech CAPM 351 virus - the original strain released in Australia. Levels of resistance to infection were generally higher than for unselected domestic rabbits and also differed (0-73% infection rates) between wild populations. Resistance was lower in populations from cooler, wetter regions and also low in arid regions with the highest resistance seen within zones of moderate rainfall. These findings suggest the external influences of non-pathogenic calicivirus in cooler, wetter areas and poor recruitment in arid populations may influence the development rate of resistance in Australia. © Copyright Cambridge University Press 2012.


Strive T.,CSIRO | Strive T.,University of Canberra | Elsworth P.,University of Canberra | Elsworth P.,Robert Wicks Pest Animals Research Center | And 7 more authors.
Veterinary Research | Year: 2013

The endemic non-pathogenic Australian rabbit calicivirus RCV-A1 is known to provide some cross protection to lethal infection with the closely related Rabbit Haemorrhagic Disease Virus (RHDV). Despite its obvious negative impacts on viral biocontrol of introduced European rabbits in Australia, little is known about the extent and mechanisms of this cross protection. In this study 46 rabbits from a colony naturally infected with RCV-A1 were exposed to RHDV. Survival rates and survival times did not correlate with titres of serum antibodies specific to RCV-A1 or cross reacting to RHDV, but were instead influenced by the time between infection with the two viruses, demonstrating for the first time that the cross protection to lethal RHDV infection is transient. These findings are an important step towards a better understanding of the complex interactions of co-occurring pathogenic and non-pathogenic lagoviruses. © 2013 Strive et al.; licensee BioMed Central Ltd.


Mutze G.,Natural Resources Management Biosecurity Unit | Sinclair R.,Natural Resources Management Biosecurity Unit | Peacock D.,Natural Resources Management Biosecurity Unit | Kovaliski J.,Natural Resources Management Biosecurity Unit | Capucci L.,Instituto Zooprofilattico Sperimentale della Lombardia e dellEmilia Romagna
Wildlife Research | Year: 2010

Context. European rabbits are serious environmental and agricultural pests throughout their range in Australia. Rabbit haemorrhagic disease virus (RHDV) greatly reduced rabbit numbers in arid central Australia but had less impact in cooler, higher-rainfall areas. RHDV-like benign caliciviruses (bCVs) have been implicated in limiting the impact of RHDV in the higher-rainfall regions of Australia and also in Europe. Aims. Experimental releases of RHDV on bait were tested as a means of initiating disease outbreaks. Serological evidence of antibodies to bCVs was examined to determine whether they reduce mortality rates and/or spread of the released RHDV, and how that might influence the effectiveness of future RHDV releases for rabbit management. Methods. Four experimental releases were conducted in high-rainfall and coastal regions of southern Australia. Virus activity was implied from recapture rates and serological changes in marked rabbits, and genetic sequencing of virus recovered from dead rabbits. Changes in rabbit abundance were estimated from spotlight transect counts. Key results. Release of RHDV on bait produced disease outbreaks that challenged almost all animals within the general release area and spread up to 4km beyond the release sites. Recapture rates were high in marked rabbits that possessed antibodies from previous exposure to RHDV and extremely low amongst rabbits that lacked any detectable antibodies. Rabbits carrying antibodies classified as being due to previous infection with bCVs had recapture rates that were dependent on circulating antibody titre and were ∼55% of recapture rates in rabbits with clear antibodies to RHDV. Conclusions. This is the first quantified evidence that antibodies produced against bCVs provide significant protection against RHD outbreaks in field populations of rabbits. Implications. bCVs can greatly reduce the impact of RHDV on wild-rabbit populations in Australia and presumably elsewhere. RHDV can be effectively released on bait although further releases are likely to be of minor or inconsistent benefit for controlling rabbit numbers where bCVs are common. © 2010 CSIRO.


Moulton M.P.,University of Florida | Cropper Jr. W.P.,University of Florida | Moulton L.E.,University of Florida | Avery M.L.,National United University | Peacock D.,Natural Resources Management Biosecurity Unit
Biodiversity and Conservation | Year: 2012

Introduced species are widely believed to represent a significant threat to conservation of biological diversity. A better understanding of the ecological factors associated with successful species establishment should lead to improved management and mitigation of these introductions. The "propagule pressure hypothesis", implying a greater chance of successful introduction with greater numbers introduced, has been widely accepted as a principal ecological factor in explaining establishment of exotic species. The historical record of bird introductions in a few locations, including the state of Victoria in Australia, has been advanced as the principal quantitative support for the hypothesis. We compiled lists of bird species introductions into Australia from several sources, and discovered inconsistencies in the records of introductions. In a series of comparisons, we found that the historical record of passerine introductions to Australia does not support the propagule pressure hypothesis unless superfluous introductions of already successful species are included. An additional problem with previous analyses is the inclusion of unsuccessful haphazard cage escapes. © 2011 Springer Science+Business Media B.V.


Peacock D.,Natural Resources Management Biosecurity Unit | Abbott I.,Caddy Avenue | Abbott I.,Bentley Delivery Center
Australian Journal of Zoology | Year: 2013

We investigated two questions: Why did most historical releases of rabbits on the Australian mainland fail? And why did many releases of rabbits on islands around Australia persist? We reviewed historical sources and present here nearly 300 records of the importation, sale, transportation and release of rabbits in the period 1788-1900, with >90 records before the popularly cited 1859 Barwon Park (near Geelong, Victoria) release by Thomas Austin. Similarly, we present records of localised impact of quolls (especially Dasyurus viverrinus) on rabbits and poultry, indicative of the great abundance of quolls. Rabbits were often imported and traded and releases were frequent and widespread. This evidence implicates native predators, particularly quolls (Dasyurus spp.) as responsible for the widespread and early failure of rabbits to establish on mainland Australia. In contrast, rabbits thrived on many islands, nearly all of which lacked cursorial natural enemies. We suggest that these accounts support the establishment of rabbits from several locations, with Barwon Park being a primary location and rabbit source. © CSIRO 2013.


Peacock D.,Natural Resources Management Biosecurity Unit | Abbott I.,University of Western Australia | Abbott I.,Bentley Delivery Center
Australian Journal of Zoology | Year: 2010

We reviewed historical literature and obtained nearly 200 records of the mongoose in Australia up to 1942. Although the earliest importations (from 1855) were for its snake-killing prowess, often as entertainment, its perceived potential as a control agent for the European rabbit (Oryctolagus cuniculus) plague saw concerted introductions made in New South Wales, Victoria and South Australia, primarily in 1883 and 1884. At least 1000 mongoose were released to control rabbits at 14 reported release locations in these states. As many as 700 of these mongoose were reported released in one New South Wales rabbit-control trial. These numbers indicate that insufficient propagule pressure does not explain why Australia escaped the additional devastation of an established mongoose population. The only reason stated for the failure of the mongoose releases to control rabbits is destruction of the mongoose by rabbit trappers, both inadvertently and in seeking to protect their employment. Unfavourable climate was implicated by CLIMATCH modelling in the failure of all releases, especially those into semiarid areas such as western New South Wales. No contemporary detail could be located of the reported 1884 failed introduction of 'numbers' of mongoose into North Queensland to control rats in sugarcane plantations. © 2010 CSIRO.

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