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Michael C Bull - One of the best experts on this subject based on the ideXlab platform.
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a nose for lizards can a detection dog locate the endangered pygmy Bluetongue lizard tiliqua adelaidensis
Transactions of The Royal Society of South Australia, 2016Co-Authors: Torben P Nielsen, Gary Jackson, Michael C BullAbstract:ABSTRACTEnvironmental detection dogs have been used in various research and conservation projects. By detecting scent, dogs are capable of finding animals or scats that are virtually undetectable to humans. The endangered pygmy Bluetongue lizard (Tiliqua adelaidensis) is endemic to heavily fragmented patches of native grassland in the mid-north region of South Australia. The lizards live in spider burrows with entrance diameters of 10–20 mm, which makes them difficult to find. This study presents the first data showing that a dog can detect pygmy Bluetongue lizards. The dog showed the ability to distinguish between pygmy Bluetongue lizard scent and the scent of sleepy lizard (Tiliqua rugosa) and bearded dragon (Pogona barbata). The dog also found more than 30 occupied lizard burrows in the field. Up until now surveys of this endangered lizard have relied on human visual detection of burrows, which is a very labour-intensive process. Although the climate and the ecology of the lizards pose a challenge to d...
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impact of foxes digging for the pygmy Bluetongue lizard tiliqua adelaidensis
Transactions of The Royal Society of South Australia, 2016Co-Authors: Torben P Nielsen, Michael C BullAbstract:ABSTRACTThe endangered pygmy Bluetongue lizard (Tiliqua adelaidensis) is endemic to heavily fragmented patches of native grassland in the mid-north region of South Australia. The lizards live in spider burrows, and suitable burrows can be a limiting factor to local populations. The invasive red fox (Vulpes vulpes) is a likely predator of the lizards. No previous research has focussed on the effects of foxes on pygmy Bluetongue lizards. This article presents observations from three sampling rounds in a single lizard activity season. During each round, burrows were located and lizard presence or absence, fox digging and burrow condition were recorded. Out of 256 monitored lizard burrows, 12 were dug out by foxes. The data show that foxes actively seek to prey on pygmy Bluetongue lizards. In several cases, the fox gave up before reaching the lizard. Dug out burrows were quickly abandoned by the surviving lizards and became filled in, reducing the supply of suitable burrows for the population. These data high...
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lycosid spiders are friends and enemies of the endangered pygmy Bluetongue lizard tiliqua adelaidensis
Transactions of The Royal Society of South Australia, 2012Co-Authors: Mehregan Ebrahimi, Michael C BullAbstract:AbstractThe pygmy Bluetongue lizard is an endangered species and the smallest member (average snoutto-vent length 95 mm) of the genus Tiliqua. It uses spider burrows with a single entrance for shelter and as sites to ambush passing prey. There is a little information about interactions between this lizard and the lycosid and mygalomorph spiders which construct the burrows they use. Surveys of the diet of pygmy Bluetongue lizards show they eat lycosid spiders, and one record of a partly consumed juvenile pygmy Bluetongue lizard found in a lycosid burrow suggests spiders eat lizards. This paper describes the first record of adult pygmy Bluetongue lizards being killed by lycosid spiders. It suggests a complex relationship of lizards and spiders in that the lizards rely on potentially lethal co-inhabitants of their grassland habitat to construct the burrow refuges that they require. Conservation management of this endangered lizard will need to consider both the advantages and disadvantages of maintaining spi...
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injuries to lizards conservation implications for the endangered pygmy Bluetongue lizard tiliqua adelaidensis
Wildlife Research, 2008Co-Authors: Aaron L Fenner, Michael C Bull, Mark N HutchinsonAbstract:Understanding the potential threats of predation can play a crucial role in conservation management of threatened species. We investigated the frequency of sublethal injuries to live individuals of the endangered pygmy Bluetongue lizard (Tiliqua adelaidensis). We found that there was no significant difference in the frequency of injury between males and females. However, there was a significant difference in injury frequency between adults and subadult animals and also between two close, but isolated, populations of pygmy Bluetongue lizards. These data can be used, with caution, to understand the predation risks in natural populations of this species. They also suggest that predation would be a significant hazard that must be considered in any translocation program that is considered for this species.
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habitat requirements of the endangered pygmy Bluetongue lizard tiliqua adelaidensis
Biological Conservation, 2007Co-Authors: Nicholas J Souter, Michael C Bull, Mark Lethbridge, Mark N HutchinsonAbstract:Abstract The pygmy Bluetongue lizard, Tiliqua adelaidensis, occupies spider burrows as home sites. It is an endangered species, known from only 19 small natural grassland sites in the mid-north of South Australia, all on privately owned land. Habitat requirements of the pygmy Bluetongue lizard were investigated at four sites. Both within and between sites, lizards were more likely to be found in areas with a greater number of deep spider burrows. Areas where lizards were not found tended to lack these burrows. Strong site similarities were found for a range of habitat parameters examined. Within these grasslands there was no specific vegetation community associated with areas occupied by pygmy Bluetongue lizards. However there was a distinct vegetation community associated with an absence of lizards. Generally there was no difference in the abundance and diversity of ground dwelling invertebrates between areas with and without lizards. As the only protected area of natural grassland within the known distribution, Mokota Conservation Park was assessed as a potential reintroduction site. It was found to be unsuitable due to a low number of deep spider burrows and a vegetation community similar to that found in uninhabited areas of known lizard inhabited sites. Unless other conservation areas can be established, preservation of this lizard will rely on habitat management by private land holders. Community goodwill and informed advice to the land holders will be essential in this process.
Mark N Hutchinson - One of the best experts on this subject based on the ideXlab platform.
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injuries to lizards conservation implications for the endangered pygmy Bluetongue lizard tiliqua adelaidensis
Wildlife Research, 2008Co-Authors: Aaron L Fenner, Michael C Bull, Mark N HutchinsonAbstract:Understanding the potential threats of predation can play a crucial role in conservation management of threatened species. We investigated the frequency of sublethal injuries to live individuals of the endangered pygmy Bluetongue lizard (Tiliqua adelaidensis). We found that there was no significant difference in the frequency of injury between males and females. However, there was a significant difference in injury frequency between adults and subadult animals and also between two close, but isolated, populations of pygmy Bluetongue lizards. These data can be used, with caution, to understand the predation risks in natural populations of this species. They also suggest that predation would be a significant hazard that must be considered in any translocation program that is considered for this species.
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habitat requirements of the endangered pygmy Bluetongue lizard tiliqua adelaidensis
Biological Conservation, 2007Co-Authors: Nicholas J Souter, Michael C Bull, Mark Lethbridge, Mark N HutchinsonAbstract:Abstract The pygmy Bluetongue lizard, Tiliqua adelaidensis, occupies spider burrows as home sites. It is an endangered species, known from only 19 small natural grassland sites in the mid-north of South Australia, all on privately owned land. Habitat requirements of the pygmy Bluetongue lizard were investigated at four sites. Both within and between sites, lizards were more likely to be found in areas with a greater number of deep spider burrows. Areas where lizards were not found tended to lack these burrows. Strong site similarities were found for a range of habitat parameters examined. Within these grasslands there was no specific vegetation community associated with areas occupied by pygmy Bluetongue lizards. However there was a distinct vegetation community associated with an absence of lizards. Generally there was no difference in the abundance and diversity of ground dwelling invertebrates between areas with and without lizards. As the only protected area of natural grassland within the known distribution, Mokota Conservation Park was assessed as a potential reintroduction site. It was found to be unsuitable due to a low number of deep spider burrows and a vegetation community similar to that found in uninhabited areas of known lizard inhabited sites. Unless other conservation areas can be established, preservation of this lizard will rely on habitat management by private land holders. Community goodwill and informed advice to the land holders will be essential in this process.
Bernd Hoffmann - One of the best experts on this subject based on the ideXlab platform.
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Bluetongue Virus
2013Co-Authors: Bernd Hoffmann, Michael Saßerath, Sabine Thalheim, Claudia Bunzenthal, Günter Strebelow, Martin BeerAbstract:Reemerging Bluetongue virus serotype 8 (BTV-8) in Germany was detected fi rst in May 2007 in a sentinel cow and in February 2008 in an export heifer. Reemergence was confi rmed by retesting the samples, experimental inoculation, fi ngerprinting analysis, and virus isolation. Overwintering of BTV-8 and continuous low-level infections are assumed. Bluetongue virus (BTV) is a double-stranded RNA virus of the genus Orbivirus. BTV is transmitted to its hosts by the bite of Culicoides spp. midges. It causes a noncontagious, arthropod-borne disease of domestic and wild ruminants and camelids (1); disease can be serious, particularly in sheep (2–4). BTV had never been reported in any European country north of the Alps until August 2006, when outbreaks of BTV serotype 8 (BTV-8) were almost simultaneously discovered in the Netherlands, Belgium, Germany, and France (5–7). In 2006, a total of 893 cases were detected in Germany, but the source of initial virus introduction remains unknown. Subsequently, BTV-8 overwintered in the region, spread over most of the country, and led to almost 21,000 new cases in 2007 in Germany. BTV-8 infections spread to additional European countries, e.g., the United Kingdom, Switzerland, the Czech Republic
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monitoring of putative vectors of Bluetongue virus serotype 8 germany
Emerging Infectious Diseases, 2009Co-Authors: Bernd Hoffmann, Burkhard Bauer, C Bauer, Hans Joachim Batza, Martin Beer, Peterhenning Clausen, Martin Geier, Jorn Gethmann, Ellen Kiel, Gabriele LiebischAbstract:To identify the vectors of Bluetongue virus (BTV) in Germany, we monitored Culicoides spp. biting midges during April 2007–May 2008. Molecular characterization of batches of midges that tested positive for BTV suggests C. obsoletus sensu stricto as a relevant vector of Bluetongue disease in central Europe.
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epidemiology of Bluetongue virus serotype 8 germany
Emerging Infectious Diseases, 2009Co-Authors: Franz Josef Conraths, Martin Beer, Jorn Gethmann, Christoph Staubach, Thomas C Mettenleiter, Bernd HoffmannAbstract:In Germany, Bluetongue disease had not been reported before 2006. During August 2006–August 2008, >24,000 Bluetongue virus serotype 8 infections were reported, most (20,635) in 2007. In 2006 and 2007, respectively, case-fatality rates were 6.4% and 13.1% for cattle and 37.5% and 41.5% for sheep. Vaccination in 2008 decreased cases.
P S Mellor - One of the best experts on this subject based on the ideXlab platform.
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investigating incursions of Bluetongue virus using a model of long distance culicoides biting midge dispersal
Transboundary and Emerging Diseases, 2013Co-Authors: P S Mellor, Laura Burgin, J Gloster, Christopher Sanders, Simon Gubbins, Simon CarpenterAbstract:Bluetongue virus (BTV) is an economically important pathogen of ruminants that is the aetiological agent of the haemorrhagic disease Bluetongue. Bluetongue virus is biologically transmitted by Culicoides biting midges (Diptera: Ceratopogonidae), and long-range dispersal of infected vector species contributes substantially to the rapid spread of the virus. The range of semi-passive flights of infected Culicoides on prevailing winds has been inferred to reach several hundred kilometres in a single night over water bodies. In this study, an atmospheric dispersion model was parameterized to simulate Culicoides flight activity based on dedicated entomological data sets collected in the UK. Five outbreaks of BTV in Europe were used to evaluate the model for use as an early warning tool and for retrospective analyses of BTV incursions. In each case, the generated predictions were consistent with epidemiological observations confirming its reliability for use in disease outbreak management. Furthermore, the model aided policy makers to predict, contain and eradicate BTV outbreaks in the UK during 2007 and 2008.
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culicoides and the emergence of Bluetongue virus in northern europe
Trends in Microbiology, 2009Co-Authors: Simon Carpenter, Anthony J Wilson, P S MellorAbstract:In June 2006, Bluetongue virus, an arboviral pathogen of ruminants, appeared in northern Europe for the first time, successfully overwintered and subsequently caused substantial losses to the farming sector in 2007 and 2008. This emergence served as a test of how the probability of arboviral incursion into new regions is assessed and has highlighted the reliance of decision making on paradigms that are not always underpinned by basic biological data. In this review, we highlight those areas of the epidemiology of Bluetongue that are poorly understood, reflect upon why certain vital areas of research have received little attention and, finally, examine strategies that could aid future risk assessment and intervention.
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where does Bluetongue virus sleep in the winter
PLOS Biology, 2008Co-Authors: Anthony J Wilson, Karin E Darpel, P S MellorAbstract:Bluetongue virus (BTV) is spread by the bites of Culicoides midges (Figure 1), and can infect ruminant livestock such as cattle, sheep, and goats, wild ruminants such as deer, and camelids. Some infected animals develop the disease known as Bluetongue, with clinical signs ranging from apathy and weight loss to swollen heads, tender feet and death (Figure 2). Historically a tropical and subtropical disease, Bluetongue has become a regular visitor to southern Europe in the last decade [1,2]. Although growth in the global trade in livestock may have increased the frequency with which exotic viruses are introduced into Europe, the increasing tendency of those introduced strains to persist and spread is probably best explained by changes to the European climate [3], and several direct and indirect links between climate and BTV transmission have been identified [2]. BTV reached northern Europe for the first time in 2006, and affected around 2,000 holdings before reports ceased in early January 2007. The outbreak then re-emerged months later [4] and spread to a further 45,000 holdings by the end of the year, making it the most economically damaging outbreak of Bluetongue ever seen [2,5]. Figure 1 Blood-Feeding Culicoides Midges Figure 2 Moderate (Left) and Severe (Right) Clinical Signs of Bluetongue in Sheep Although this re-emergence was a timely reminder of the ability of BTV to escape detection for months at a time in temperate regions, the ability of BTV to “overwinter” has been recognised for decades (e.g., [6–8]). Both midge activity and virus replication in the midge cease at cool temperatures, interrupting transmission, but outbreaks sometimes resume after “silent” periods of several months—far longer than the typical lifespan of the adult vector or the normal period of infectious viraemia in a mammalian host [7–9]. Where, then, might the virus persist without detection during the winter months?
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prediction of Bluetongue vector distribution in europe and north africa using satellite imagery
Veterinary Microbiology, 2003Co-Authors: Andrew J Tatem, P S Mellor, Matthew Baylis, Bethan V. Purse, Ruben Capela, I Pena, David J RogersAbstract:Bluetongue is an infectious, non-contagious arboviral disease thought to infect all known ruminant species. Since 1998, an unprecedented epizootic of the disease has occurred in the Mediterranean region, resulting in the deaths of over 800,000 sheep to date. Bluetongue virus (BTV) is transmitted by biting midges of which one species, Culicoides imicola, is the major vector in the old world. C. imicola was trapped for 2 years at 87 sites across Portugal and models were developed for predicting the presence and abundance of the midge at these sites. Discriminant analysis was used to identify the best models from 40 temporally Fourier-processed 1 km spatial resolution remotely-sensed variables. The best models correctly predicted presence and absence at 83 of the 87 sites, and abundance at 76 sites. The models were then used to predict C. imicola presence and abundance elsewhere across Europe and north Africa. C. imicola was predicted to be present and in high abundance at the majority of areas affected in the recent Bluetongue epizootic, including the Balearics, Sardinia, Corsica, Sicily, areas of mainland Italy, large areas of Greece, western Turkey and northern Algeria and Tunisia.
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identification of a novel Bluetongue virus vector species of culicoides in sicily
Veterinary Record, 2003Co-Authors: S Caracappa, Alessandra Torina, A Guercio, Fabrizio Vitale, A Calabro, G Purpari, Vincenzo Ferrantelli, Maria Vitale, P S MellorAbstract:The vectors of Bluetongue virus are certain species of Culicoides biting midges, and in the Mediterranean area Culicoides imicola has long been considered to be the only field vector. In Sicily an entomological and serological surveillance programme has been in operation since the autumn of 2000, which has shown that the prevalence and abundance of C imicola is lower than in many other Italian regions. Moreover, in 2002, there were outbreaks of Bluetongue in the absence of C imicola, and in these regions Bluetongue viral RNA was detected by means of a nested reverse-transcriptase PCR in wild-caught, non-blood-engorged, parous Culicoides pulicaris. Furthermore, Bluetongue virus serotype 2 was isolated on five occasions from extracts of non-blood-engorged parous C pulicaris by using embryonated hens eggs and BHK-21 cells as assay systems. These findings suggest that in parts of Italy and possibly in other areas of Europe, where C imicola is absent or rare, C pulicaris may act as a fully competent vector of Bluetongue virus.
Richard Shine - One of the best experts on this subject based on the ideXlab platform.
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activity patterns and movements of free ranging Bluetongue lizards tiliqua scincoides intermedia and tiliqua multifasciata in the australian wet dry tropics
Journal of Herpetology, 2014Co-Authors: Samantha J Pricerees, Gregory P Brown, Richard ShineAbstract:Abstract We used GPS-based radiotelemetry to quantify diel activity patterns and movements by two species of large scincid lizards in the Australian wet-dry tropics. From an average of 63 days tracking of 54 Northern Bluetongues (Tiliqua scincoides intermedia) and 42 days tracking of 8 Centralian Bluetongues (Tiliqua multifasciata), we obtained 53,801 and 8,139 data points, respectively, on lizard locations over a 13-month period. Lizard species, sex, and study site had relatively little effect on distances moved, at both daily and hourly levels. However, Northern Bluetongues moved further per day than did Centralian Bluetongues at a site where they were sympatric. Most movements were <20 m, with longer movements (dispersal between core areas within the wider home range) occurring primarily during midmorning and late afternoon. The only major effect of ambient temperatures on lizard activity patterns likely was that midday movements were precluded by the risk of overheating; at all other times of the day ...
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school for skinks can conditioned taste aversion enable Bluetongue lizards tiliqua scincoides to avoid toxic cane toads rhinella marina as prey
Ethology, 2011Co-Authors: Samantha J Pricerees, Jonathan K Webb, Richard ShineAbstract:The invasion of cane toads (Rhinella marina) through Australia imperils native predators that are killed if they consume these toxic anurans. The magnitude of impact depends upon the predators’ capacity for aversion learning: toad impact is lower if predators can learn not to attack toads. In laboratory trials, we assessed whether Bluetongue lizards (Tiliqua scincoides) ‐ a species under severe threat from toads ‐ are capable of learned taste aversion and whether we can facilitate that learning by exposing lizards to toad tissue combined with a nausea-inducing chemical (lithium chloride). Captive Bluetongues rapidly learned to avoid the ‘unpalatable’ food. Taste aversion also developed (albeit less strongly) in response to meals of minced cane toad alone. Our data suggest that taste aversion learning may help Bluetongue lizards survive the onslaught of cane toads, but that many encounters will be fatal because the toxin content of toads is so high relative to lizard tolerance of those toxins. Thus, baiting with nausea-inducing (but non-lethal) toad products might provide a feasible management option to reduce the impact of cane toad invasion on these native predators.
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predation on toxic cane toads bufo marinus may imperil Bluetongue lizards tiliqua scincoides intermedia scincidae in tropical australia
Wildlife Research, 2010Co-Authors: Samantha J Pricerees, Gregory P Brown, Richard ShineAbstract:Context. Detecting ecological impacts of invasive species can be extremely difficult. Even major population declines may be undetectable without extensive long-term data if the affected taxon is rare and/or difficult to census, and exhibits stochastic variation in abundance as a result of other factors. Our data suggest such a situation in an iconic Australian reptile species, the Bluetongue lizard. Originally restricted to Central and South America, cane toads (Bufo marinus) are rapidly spreading through tropical Australia. Most native predators have no evolutionary history of exposure to the toads’ distinctive chemical defences (bufadienolides), and many varanid lizards, elapid snakes, crocodiles and marsupials have been killed when they have attempted to consume toads. Aims. Scincid lizards have not been considered vulnerable to toad invasion; however, one lineage (the Bluetongues, genus Tiliqua) consists of large omnivores that may be affected. Our field and laboratory research aimed to elucidate this concern. Methods. Nightly surveys for Bluetongue lizards (Tiliqua scincoides intermedia) and cane toads were conducted along two adjacent roadways on the Adelaide River floodplain of the Northern Territory. Scent discrimination trials in the laboratory assessed lizard responses to chemical cues from three food types (native frogs, cane toads and ‘preferred foods’) by counting tongue-flicks and biting elicited by cotton swabs. A subset of lizards was presented with live toads. Key results. Numbers of Bluetongues encountered during standardised field surveys in the Darwin region declined soon after toads arrived, and we have not recorded a single lizard for the last 20 months. In the laboratory, foraging responses of Bluetongues were as intense to cane-toad scent as to the scent of native frogs, and many of the lizards we tested attempted to consume toads, and were poisoned as a result. Conclusions and implications. The population decline of Bluetongues in this region appears to have been the direct result of fatal ingestion of toxic cane toads. Our studies thus add a scincid lizard species to the list of native Australian predators imperilled by cane-toad invasion, and point to the difficulty of detecting invader impact even for an iconic species in a system subject to detailed survey work.