The Experts below are selected from a list of 141 Experts worldwide ranked by ideXlab platform
A L Bishop - One of the best experts on this subject based on the ideXlab platform.
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Factors affecting the distribution of Culicoides spp. (Diptera: Ceratopogonidae) vectors of bluetongue virus (BTV) in Australia
Australian Journal of Entomology, 2015Co-Authors: A L Bishop, Lorraine J Spohr, Anne M Harris, Damian CollinsAbstract:This study examined environmental and geographical factors affecting the distribution of the bluetongue virus vectors Culicoides brevitarsis Kieffer, C. actoni Smith, C. fulvus Sen and Das Gupta and C. wadai Kitaoka in Australia using graphical analysis. Calculations and mapping were carried out in the R programming environment using freely available data. Average low temperatures of 13.5°C in June and in September were estimated as thresholds and expressed as contours at which C. brevitarsis activity ceases and then recommences during and after winter, respectively. The June threshold also designated areas where populations would be unable to survive the winter. There was substantial variability in the contours between years, around which the activity of C. brevitarsis would be correspondingly dynamic. Culicoides wadai, C. actoni and C. fulvus appeared to be less tolerant of low temperatures. A high temperature limit was proposed at a maximum 35°C during summer. Culicoides brevitarsis was found in areas above and below this temperature, while C. actoni, C. fulvus and C. wadai occurred mainly in coastal environments at maximum temperatures of less than 35°C. Possible effects of global warming were considered with 1°C or 2°C rises in temperature. Changes to low temperature thresholds could expose greater areas of southern Australia to vector activity, while temperature rises in the north could increase the size of areas in which temperatures are lethal to the vectors. Rainfall had no apparent effect on C. brevitarsis during the northern wet and dry seasons. Distributions of C. brevitarsis and cattle overlapped until both ended with the climatic change to desert, which formed a physical barrier preventing C. brevitarsis movement to the south. Temperature restricted associations between C. brevitarsis and sheep. The other Culicoides spp. were found outside major cattle and sheep production areas. Apart from seasonal and dynamic activity around the contours, cattle and sheep in areas below a June average temperature of 13.5°C should remain vector free at current climatic temperatures.
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attraction of Culicoides brevitarsis kieffer diptera ceratopogonidae and culex annulirostris skuse diptera culicidae to simulated visual and chemical stimuli from cattle
Australian Journal of Entomology, 2008Co-Authors: A L Bishop, H J Mckenzie, Lorraine J SpohrAbstract:Different host-seeking responses to cattle by Culicoides brevitarsis and Culex annulirostris were found using two-dimensional cattle-shapes and simulated stimuli. Culicoides brevitarsis was attracted to the respiratory chemicals CO2 and CO2 + octenol but not to octenol alone. It was attracted to cattle-shape when CO2 + octenol was also present and when the shape was enhanced with visible and infrared light. Culex annulirostris was attracted to each chemical treatment but not to any visual stimuli. Orientation of the host, possibly in relation to wind direction, may also be important but requires further consideration. The detection of behavioural differences between the species was dependent on the positioning of attractants and traps in relation to the host image. Responses by C. brevitarsis to CO2 + octenol and the basic shape were only recorded in sticky traps. Contact with the shape was recorded initially on the shape head but preference was shown later to be for the ridge-line of the back. The response by Cx. annulirostris to CO2 + octenol was only recorded in light traps placed centrally and above the shape. It is proposed that the initial location of hosts by C. brevitarsis is by visual stimuli. Attraction to CO2 + octenol is secondary and probably only occurs close to the host. The chemicals help the midge to recognise and come to the potential host where landing is induced visually near the interface between the backline of the host and the background. The primary response by Cx. annulirostris is to CO2 and octenol although these did not appear to bring this insect on to the host. Covers could be used to protect cattle from C. brevitarsis (but not Cx. annulirostris) by blocking the visual stimuli.
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Light trapping of biting midges Culicoides spp. (Diptera: Ceratopogonidae) with green light-emitting diodes
Australian Journal of Entomology, 2006Co-Authors: A L Bishop, H J Mckenzie, Lorraine J Spohr, Glenn A Bellis, Anne M Harris, Ross Worrall, Lorna MelvilleAbstract:A study of responses by Culicoides spp. to light traps with light-emitting diodes (LEDs) confirmed that the livestock virus vector, Culicoides brevitarsis Kieffer, was preferentially attracted to green light. Four species shown previously to respond to blue light exhibited significantly higher responses to ultraviolet (UV) light. Field trials comparing green LEDs with incandescent lights in New South Wales, Northern Territory and East Timor confirmed the superiority of green LEDs for catching C. brevitarsis. The green LED traps also had a significant advantage over incandescent traps for a wide range of Culicoides species. These included: species whose ultimate preference was for UV, most species that are proven or potential vectors of viruses affecting Australian livestock and native animals and the main species affecting humans in northern Australia. Use of green LEDs has been adopted for trapping C. brevitarsis, especially in its marginal and low-density areas, and for detecting incursions of new Culicoides spp. into Australia. Use could be possible for species in other insect Orders.
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interactions between dung beetles coleoptera scarabaeidae and the arbovirus vector Culicoides brevitarsis kieffer diptera ceratopogonidae
Australian Journal of Entomology, 2005Co-Authors: A L Bishop, H J Mckenzie, Lorraine J Spohr, I M BarchiaAbstract:The potential for dung beetles to reduce populations of the biting midge and arbovirus vector Culicoides brevitarsis in bovine dung was studied in the Hunter Valley, New South Wales (NSW) between 1999 and 2003 using natural populations of insects. Preliminary work to develop experimental procedures showed that: a few C. brevitarsis could survive in buried dung; dung beetles and C. brevitarsis coming to dung were unaffected by a background of shade-cloth used experimentally to prevent dung burial; the most abundant dung beetle, Onthophagus gazella L. and C. brevitarsis oviposition occurred concurrently in the first 2 d after dung deposition, and the potential for interaction between dung beetles and C. brevitarsis was greatest in open pasture adjacent to trees where cattle congregate at night. Laboratory experiments on dung burial showed that C. brevitarsis numbers decreased as numbers of dung beetles increased or as the dry weight of dung decreased due to burial. This was seldom reflected in the field where, although significant burial occurred experimentally in 9 of 20 trials over 3 years, a significant decline in C. brevitarsis numbers attributable to burial only occurred once. C. brevitarsis numbers in the field were lower in unburied dung in 70% of trials. Differences were significant twice and were considered the result of dung disturbance. In the laboratory, decreasing numbers of C. brevitarsis were related to three characteristics of disturbance: the flattening, spreading and reduction in wet weight of the dung. Evidence of C. brevitarsis activity throughout coastal NSW suggests that, while C. brevitarsis numbers may be modified by dung beetles, the interaction is insufficient to prevent their increase, spread and ability to transmit viruses to livestock.
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effects of altitude distance and waves of movement on the dispersal in australia of the arbovirus vector Culicoides brevitarsis kieffer diptera ceratopogonidae
Preventive Veterinary Medicine, 2004Co-Authors: A L Bishop, Lorraine J Spohr, I M BarchiaAbstract:Abstract The dispersal of the biting midge and arbovirus vector Culicoides brevitarsis in the Bellinger, Macleay and Hastings river valleys and up the escarpment of the great dividing range (GDR) of mid-northern coastal New South Wales, Australia, from 1995 to 2003 was studied. The midge moved up these valleys from the endemic coastal plain in at least two waves between October and May, and both waves were modelled. Dispersal time can be explained by direct distance from the coast and the altitude of the sites. Dispersal times due to distance were similar at 18.2 ± 2.2 (S.D.) and 15.9 ± 2.6 weeks per 100 km for first- and second-occurrences at fixed altitude. Time of the first wave was extended 0.48 ± 0.22 weeks for every 100-m rise in altitude and the second by 1.14 ± 0.24 weeks for every 100-m rise for a set distance. Although C. brevitarsis can move up the escarpment of the GDR (and possibly transmit virus), vector dispersal, survival and establishment at and beyond the top of the range are limited. A third model showed that previously described slower movement of C. brevitarsis up the more-southerly Hunter valley relative to movements down the coastal plain also was related to increasing altitude.
I M Barchia - One of the best experts on this subject based on the ideXlab platform.
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interactions between dung beetles coleoptera scarabaeidae and the arbovirus vector Culicoides brevitarsis kieffer diptera ceratopogonidae
Australian Journal of Entomology, 2005Co-Authors: A L Bishop, H J Mckenzie, Lorraine J Spohr, I M BarchiaAbstract:The potential for dung beetles to reduce populations of the biting midge and arbovirus vector Culicoides brevitarsis in bovine dung was studied in the Hunter Valley, New South Wales (NSW) between 1999 and 2003 using natural populations of insects. Preliminary work to develop experimental procedures showed that: a few C. brevitarsis could survive in buried dung; dung beetles and C. brevitarsis coming to dung were unaffected by a background of shade-cloth used experimentally to prevent dung burial; the most abundant dung beetle, Onthophagus gazella L. and C. brevitarsis oviposition occurred concurrently in the first 2 d after dung deposition, and the potential for interaction between dung beetles and C. brevitarsis was greatest in open pasture adjacent to trees where cattle congregate at night. Laboratory experiments on dung burial showed that C. brevitarsis numbers decreased as numbers of dung beetles increased or as the dry weight of dung decreased due to burial. This was seldom reflected in the field where, although significant burial occurred experimentally in 9 of 20 trials over 3 years, a significant decline in C. brevitarsis numbers attributable to burial only occurred once. C. brevitarsis numbers in the field were lower in unburied dung in 70% of trials. Differences were significant twice and were considered the result of dung disturbance. In the laboratory, decreasing numbers of C. brevitarsis were related to three characteristics of disturbance: the flattening, spreading and reduction in wet weight of the dung. Evidence of C. brevitarsis activity throughout coastal NSW suggests that, while C. brevitarsis numbers may be modified by dung beetles, the interaction is insufficient to prevent their increase, spread and ability to transmit viruses to livestock.
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effects of altitude distance and waves of movement on the dispersal in australia of the arbovirus vector Culicoides brevitarsis kieffer diptera ceratopogonidae
Preventive Veterinary Medicine, 2004Co-Authors: A L Bishop, Lorraine J Spohr, I M BarchiaAbstract:Abstract The dispersal of the biting midge and arbovirus vector Culicoides brevitarsis in the Bellinger, Macleay and Hastings river valleys and up the escarpment of the great dividing range (GDR) of mid-northern coastal New South Wales, Australia, from 1995 to 2003 was studied. The midge moved up these valleys from the endemic coastal plain in at least two waves between October and May, and both waves were modelled. Dispersal time can be explained by direct distance from the coast and the altitude of the sites. Dispersal times due to distance were similar at 18.2 ± 2.2 (S.D.) and 15.9 ± 2.6 weeks per 100 km for first- and second-occurrences at fixed altitude. Time of the first wave was extended 0.48 ± 0.22 weeks for every 100-m rise in altitude and the second by 1.14 ± 0.24 weeks for every 100-m rise for a set distance. Although C. brevitarsis can move up the escarpment of the GDR (and possibly transmit virus), vector dispersal, survival and establishment at and beyond the top of the range are limited. A third model showed that previously described slower movement of C. brevitarsis up the more-southerly Hunter valley relative to movements down the coastal plain also was related to increasing altitude.
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factors affecting the spread of Culicoides brevitarsis at the southern limit of distribution in eastern australia
Veterinaria Italiana, 2004Co-Authors: A L Bishop, Lorraine J Spohr, I M BarchiaAbstract:Summary Culicoides brevitarsis Kieffer is the main vector of bluetongue and Akabane viruses in Australia. Its threat to animal health and livestock exports requires that areas free of the vector and viruses be defined clearly. In New South Wales, survival of the vector over winter is limited to the northern coastal plains. C. brevitarsis therefore has to reinfest areas outside the endemic area each year. Models have been developed to predict the extent and nature of its movements. It can move at different rates and this is partly due to significant delays of movement due to the barrier formed by the altitude of the Great Dividing Range. C. brevitarsis subsequently retains a coastal distribution in most years. At the end of the season, the times when activity would effectively cease can be estimated from temperature data. These data allow evidenced-based conclusions on zonal and seasonal freedom to be made in combination with light trap monitoring.
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Response of Culicoides spp. (Diptera: Ceratopogonidae) to light-emitting diodes
Australian Journal of Entomology, 2004Co-Authors: A L Bishop, H J Mckenzie, Lorraine J Spohr, Ross Worrall, I M BarchiaAbstract:Light traps with incandescent globes are used in a national monitoring program to detect the presence of Culicoides spp. responsible for the transmission of viruses to livestock and native animals. Recent events have suggested that the efficiency of these traps should be reconsidered and possibly improved. Subsequently, the response of eight species of Culicoides to light-emitting diodes (LEDs) was determined at two locations in New South Wales. Culicoides austropalpalis Lee & Reye, C. bunrooiensis Lee & Reye and C. marksi Lee & Reye were attracted to blue light. Responses to blue and green light could not be separated for C. bundyensis Lee & Reye, C. dycei Lee & Reye, C. nattiensis Lee & Reye and C. victoriae Macfie. Culicoides brevitarsis Kieffer was significantly attracted to green light. This species is the major vector of Akabane and bluetongue viruses in Australia. These responses were all significantly greater than the responses to the incandescent lights currently used in the light traps. The response to red light was less than the response to incandescent light for all species. Catches of C. brevitarsis were also related to the intensity of the green LEDs. These were more effective than the currently used incandescent globes at intensities between 46% and 142% of the incandescent intensity.
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models for the dispersal in australia of the arbovirus vector Culicoides brevitarsis kieffer diptera ceratopogonidae
Preventive Veterinary Medicine, 2000Co-Authors: A L Bishop, I M Barchia, Lorraine J SpohrAbstract:Abstract Culicoides brevitarsis is the main biting midge responsible for the transmission of bluetongue and Akabane viruses to livestock in Australia. Models are given for its dispersal after winter from endemic areas at the southern limit of its distribution in New South Wales (NSW); the models might also be applicable elsewhere. Model 1 shows that dispersal can be explained by distance from a key point just outside the endemic area in mid-northern/northern coastal NSW. The model provides probability data for times of first occurrence at sites within regions down the southern coastal plain or up the Hunter Valley towards (but rarely reaching) the western slopes and tablelands. Model 2 shows that the movement depends on temperature and wind speed from northerly and easterly directions. Preliminary data also are given to suggest a relationship between density in the endemic area and the maximum distance that C. brevitarsis can travel in a given year. The models can be linked to other information which in combination can provide probabilities for winter survival outside the endemic area, times of occurrence at sites where it cannot survive winter and times when activity ceases naturally at these sites at the end of the season. This information can be used to predict the potential for virus transmission and indicate zones of seasonal freedom from both vector and virus for the export of livestock.
Lorraine J Spohr - One of the best experts on this subject based on the ideXlab platform.
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Factors affecting the distribution of Culicoides spp. (Diptera: Ceratopogonidae) vectors of bluetongue virus (BTV) in Australia
Australian Journal of Entomology, 2015Co-Authors: A L Bishop, Lorraine J Spohr, Anne M Harris, Damian CollinsAbstract:This study examined environmental and geographical factors affecting the distribution of the bluetongue virus vectors Culicoides brevitarsis Kieffer, C. actoni Smith, C. fulvus Sen and Das Gupta and C. wadai Kitaoka in Australia using graphical analysis. Calculations and mapping were carried out in the R programming environment using freely available data. Average low temperatures of 13.5°C in June and in September were estimated as thresholds and expressed as contours at which C. brevitarsis activity ceases and then recommences during and after winter, respectively. The June threshold also designated areas where populations would be unable to survive the winter. There was substantial variability in the contours between years, around which the activity of C. brevitarsis would be correspondingly dynamic. Culicoides wadai, C. actoni and C. fulvus appeared to be less tolerant of low temperatures. A high temperature limit was proposed at a maximum 35°C during summer. Culicoides brevitarsis was found in areas above and below this temperature, while C. actoni, C. fulvus and C. wadai occurred mainly in coastal environments at maximum temperatures of less than 35°C. Possible effects of global warming were considered with 1°C or 2°C rises in temperature. Changes to low temperature thresholds could expose greater areas of southern Australia to vector activity, while temperature rises in the north could increase the size of areas in which temperatures are lethal to the vectors. Rainfall had no apparent effect on C. brevitarsis during the northern wet and dry seasons. Distributions of C. brevitarsis and cattle overlapped until both ended with the climatic change to desert, which formed a physical barrier preventing C. brevitarsis movement to the south. Temperature restricted associations between C. brevitarsis and sheep. The other Culicoides spp. were found outside major cattle and sheep production areas. Apart from seasonal and dynamic activity around the contours, cattle and sheep in areas below a June average temperature of 13.5°C should remain vector free at current climatic temperatures.
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attraction of Culicoides brevitarsis kieffer diptera ceratopogonidae and culex annulirostris skuse diptera culicidae to simulated visual and chemical stimuli from cattle
Australian Journal of Entomology, 2008Co-Authors: A L Bishop, H J Mckenzie, Lorraine J SpohrAbstract:Different host-seeking responses to cattle by Culicoides brevitarsis and Culex annulirostris were found using two-dimensional cattle-shapes and simulated stimuli. Culicoides brevitarsis was attracted to the respiratory chemicals CO2 and CO2 + octenol but not to octenol alone. It was attracted to cattle-shape when CO2 + octenol was also present and when the shape was enhanced with visible and infrared light. Culex annulirostris was attracted to each chemical treatment but not to any visual stimuli. Orientation of the host, possibly in relation to wind direction, may also be important but requires further consideration. The detection of behavioural differences between the species was dependent on the positioning of attractants and traps in relation to the host image. Responses by C. brevitarsis to CO2 + octenol and the basic shape were only recorded in sticky traps. Contact with the shape was recorded initially on the shape head but preference was shown later to be for the ridge-line of the back. The response by Cx. annulirostris to CO2 + octenol was only recorded in light traps placed centrally and above the shape. It is proposed that the initial location of hosts by C. brevitarsis is by visual stimuli. Attraction to CO2 + octenol is secondary and probably only occurs close to the host. The chemicals help the midge to recognise and come to the potential host where landing is induced visually near the interface between the backline of the host and the background. The primary response by Cx. annulirostris is to CO2 and octenol although these did not appear to bring this insect on to the host. Covers could be used to protect cattle from C. brevitarsis (but not Cx. annulirostris) by blocking the visual stimuli.
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Light trapping of biting midges Culicoides spp. (Diptera: Ceratopogonidae) with green light-emitting diodes
Australian Journal of Entomology, 2006Co-Authors: A L Bishop, H J Mckenzie, Lorraine J Spohr, Glenn A Bellis, Anne M Harris, Ross Worrall, Lorna MelvilleAbstract:A study of responses by Culicoides spp. to light traps with light-emitting diodes (LEDs) confirmed that the livestock virus vector, Culicoides brevitarsis Kieffer, was preferentially attracted to green light. Four species shown previously to respond to blue light exhibited significantly higher responses to ultraviolet (UV) light. Field trials comparing green LEDs with incandescent lights in New South Wales, Northern Territory and East Timor confirmed the superiority of green LEDs for catching C. brevitarsis. The green LED traps also had a significant advantage over incandescent traps for a wide range of Culicoides species. These included: species whose ultimate preference was for UV, most species that are proven or potential vectors of viruses affecting Australian livestock and native animals and the main species affecting humans in northern Australia. Use of green LEDs has been adopted for trapping C. brevitarsis, especially in its marginal and low-density areas, and for detecting incursions of new Culicoides spp. into Australia. Use could be possible for species in other insect Orders.
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interactions between dung beetles coleoptera scarabaeidae and the arbovirus vector Culicoides brevitarsis kieffer diptera ceratopogonidae
Australian Journal of Entomology, 2005Co-Authors: A L Bishop, H J Mckenzie, Lorraine J Spohr, I M BarchiaAbstract:The potential for dung beetles to reduce populations of the biting midge and arbovirus vector Culicoides brevitarsis in bovine dung was studied in the Hunter Valley, New South Wales (NSW) between 1999 and 2003 using natural populations of insects. Preliminary work to develop experimental procedures showed that: a few C. brevitarsis could survive in buried dung; dung beetles and C. brevitarsis coming to dung were unaffected by a background of shade-cloth used experimentally to prevent dung burial; the most abundant dung beetle, Onthophagus gazella L. and C. brevitarsis oviposition occurred concurrently in the first 2 d after dung deposition, and the potential for interaction between dung beetles and C. brevitarsis was greatest in open pasture adjacent to trees where cattle congregate at night. Laboratory experiments on dung burial showed that C. brevitarsis numbers decreased as numbers of dung beetles increased or as the dry weight of dung decreased due to burial. This was seldom reflected in the field where, although significant burial occurred experimentally in 9 of 20 trials over 3 years, a significant decline in C. brevitarsis numbers attributable to burial only occurred once. C. brevitarsis numbers in the field were lower in unburied dung in 70% of trials. Differences were significant twice and were considered the result of dung disturbance. In the laboratory, decreasing numbers of C. brevitarsis were related to three characteristics of disturbance: the flattening, spreading and reduction in wet weight of the dung. Evidence of C. brevitarsis activity throughout coastal NSW suggests that, while C. brevitarsis numbers may be modified by dung beetles, the interaction is insufficient to prevent their increase, spread and ability to transmit viruses to livestock.
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effects of altitude distance and waves of movement on the dispersal in australia of the arbovirus vector Culicoides brevitarsis kieffer diptera ceratopogonidae
Preventive Veterinary Medicine, 2004Co-Authors: A L Bishop, Lorraine J Spohr, I M BarchiaAbstract:Abstract The dispersal of the biting midge and arbovirus vector Culicoides brevitarsis in the Bellinger, Macleay and Hastings river valleys and up the escarpment of the great dividing range (GDR) of mid-northern coastal New South Wales, Australia, from 1995 to 2003 was studied. The midge moved up these valleys from the endemic coastal plain in at least two waves between October and May, and both waves were modelled. Dispersal time can be explained by direct distance from the coast and the altitude of the sites. Dispersal times due to distance were similar at 18.2 ± 2.2 (S.D.) and 15.9 ± 2.6 weeks per 100 km for first- and second-occurrences at fixed altitude. Time of the first wave was extended 0.48 ± 0.22 weeks for every 100-m rise in altitude and the second by 1.14 ± 0.24 weeks for every 100-m rise for a set distance. Although C. brevitarsis can move up the escarpment of the GDR (and possibly transmit virus), vector dispersal, survival and establishment at and beyond the top of the range are limited. A third model showed that previously described slower movement of C. brevitarsis up the more-southerly Hunter valley relative to movements down the coastal plain also was related to increasing altitude.
Maria G Onyango - One of the best experts on this subject based on the ideXlab platform.
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genotyping of whole genome amplified reduced representation libraries reveals a cryptic population of Culicoides brevitarsis in the northern territory australia
BMC Genomics, 2016Co-Authors: Glenn A Bellis, Maria G Onyango, Appolinaire Djikeng, Nicola C Aitken, Cameron Jack, Aaron Chuah, James Oguya, Stephen Kemp, Adrian NicholasAbstract:The advent of genotyping by Next Generation Sequencing has enabled rapid discovery of thousands of single nucleotide polymorphism (SNP) markers and high throughput genotyping of large populations at an affordable cost. Genotyping by sequencing (GBS), a reduced representation library sequencing method, allows highly multiplexed sequencing of genomic subsets. This method has limitations for small organisms with low amounts of genomic DNA, such as the bluetongue virus (BTV) vectors, Culicoides midges. This study employed the GBS method to isolate SNP markers de novo from whole genome amplified Culicoides brevitarsis genomic DNA. The individuals were collected from regions representing two different Australian patterns of BTV strain distribution: the Northern Territory (NT) and the east coast. We isolated 8145 SNPs using GBS. Phylogenetic analysis conducted using the filtered 3263 SNPs revealed the presence of a distinct C. brevitarsis sub-population in the NT and this was confirmed by analysis of mitochondrial DNA. Two loci showed a very strong signal for selection and were unique to the NT population. Bayesian analysis with STRUCTURE indicated a possible two-population cluster. The results suggest that genotyping vectors with high density markers in combination with biological and environmental data is useful. However, more extensive sampling over a wider spatial and temporal range is needed. The presence of sub-structure in populations and loci under natural selection indicates the need for further investigation of the role of vectors in shaping the two Australian systems of BTV transmission. The described workflow is transferable to genotyping of small, non-model organisms, including arthropod vectors of pathogens of economic and medical importance.
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Genotyping of whole genome amplified reduced representation libraries reveals a cryptic population of Culicoides brevitarsis in the Northern Territory, Australia
BMC Genomics, 2016Co-Authors: Maria G Onyango, Glenn A Bellis, Adrian Nicholas, Appolinaire Djikeng, Steve Kemp, Nicola C Aitken, Cameron Jack, Aaron Chuah, James Oguya, Peter J WalkerAbstract:Background The advent of genotyping by Next Generation Sequencing has enabled rapid discovery of thousands of single nucleotide polymorphism (SNP) markers and high throughput genotyping of large populations at an affordable cost. Genotyping by sequencing (GBS), a reduced representation library sequencing method, allows highly multiplexed sequencing of genomic subsets. This method has limitations for small organisms with low amounts of genomic DNA, such as the bluetongue virus (BTV) vectors, Culicoides midges. Results This study employed the GBS method to isolate SNP markers de novo from whole genome amplified Culicoides brevitarsis genomic DNA. The individuals were collected from regions representing two different Australian patterns of BTV strain distribution: the Northern Territory (NT) and the east coast. We isolated 8145 SNPs using GBS. Phylogenetic analysis conducted using the filtered 3263 SNPs revealed the presence of a distinct C. brevitarsis sub-population in the NT and this was confirmed by analysis of mitochondrial DNA. Two loci showed a very strong signal for selection and were unique to the NT population. Bayesian analysis with STRUCTURE indicated a possible two-population cluster. Conclusions The results suggest that genotyping vectors with high density markers in combination with biological and environmental data is useful. However, more extensive sampling over a wider spatial and temporal range is needed. The presence of sub-structure in populations and loci under natural selection indicates the need for further investigation of the role of vectors in shaping the two Australian systems of BTV transmission. The described workflow is transferable to genotyping of small, non-model organisms, including arthropod vectors of pathogens of economic and medical importance.
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Assessment of population genetic structure in the arbovirus vector midge, Culicoides brevitarsis (Diptera: Ceratopogonidae), using multi-locus DNA microsatellites
Veterinary Research, 2015Co-Authors: Maria G Onyango, Nigel W Beebe, David Gopurenko, Glenn Bellis, Adrian Nicholas, Moses Ogugo, Appolinaire Djikeng, Steve Kemp, Peter J Walker, Jean-bernard DucheminAbstract:Bluetongue virus (BTV) is a major pathogen of ruminants that is transmitted by biting midges ( Culicoides spp.). Australian BTV serotypes have origins in Asia and are distributed across the continent into two distinct episystems, one in the north and another in the east. Culicoides brevitarsis is the major vector of BTV in Australia and is distributed across the entire geographic range of the virus. Here, we describe the isolation and use of DNA microsatellites and gauge their ability to determine population genetic connectivity of C. brevitarsis within Australia and with countries to the north. Eleven DNA microsatellite markers were isolated using a novel genomic enrichment method and identified as useful for genetic analyses of sampled populations in Australia, northern Papua New Guinea (PNG) and Timor-Leste. Significant ( P
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assessment of population genetic structure in the arbovirus vector midge Culicoides brevitarsis diptera ceratopogonidae using multi locus dna microsatellites
Veterinary Research, 2015Co-Authors: Glenn A Bellis, Maria G Onyango, Nigel W Beebe, David Gopurenko, Adrian Nicholas, Moses Ogugo, Appolinaire Djikeng, Steve KempAbstract:Bluetongue virus (BTV) is a major pathogen of ruminants that is transmitted by biting midges (Culicoides spp.). Australian BTV serotypes have origins in Asia and are distributed across the continent into two distinct episystems, one in the north and another in the east. Culicoides brevitarsis is the major vector of BTV in Australia and is distributed across the entire geographic range of the virus. Here, we describe the isolation and use of DNA microsatellites and gauge their ability to determine population genetic connectivity of C. brevitarsis within Australia and with countries to the north. Eleven DNA microsatellite markers were isolated using a novel genomic enrichment method and identified as useful for genetic analyses of sampled populations in Australia, northern Papua New Guinea (PNG) and Timor-Leste. Significant (P < 0.05) population genetic subdivision was observed between all paired regions, though the highest levels of genetic sub-division involved pair-wise tests with PNG (PNG vs. Australia (FST = 0.120) and PNG vs. Timor-Leste (FST = 0.095)). Analysis of multi-locus allelic distributions using STRUCTURE identified a most probable two-cluster population model, which separated PNG specimens from a cluster containing specimens from Timor-Leste and Australia. The source of incursions of this species in Australia is more likely to be Timor-Leste than PNG. Future incursions of BTV positive C. brevitarsis into Australia may be genetically identified to their source populations using these microsatellite loci. The vector’s panmictic genetic structure within Australia cannot explain the differential geographic distribution of BTV serotypes.
Glenn A Bellis - One of the best experts on this subject based on the ideXlab platform.
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genotyping of whole genome amplified reduced representation libraries reveals a cryptic population of Culicoides brevitarsis in the northern territory australia
BMC Genomics, 2016Co-Authors: Glenn A Bellis, Maria G Onyango, Appolinaire Djikeng, Nicola C Aitken, Cameron Jack, Aaron Chuah, James Oguya, Stephen Kemp, Adrian NicholasAbstract:The advent of genotyping by Next Generation Sequencing has enabled rapid discovery of thousands of single nucleotide polymorphism (SNP) markers and high throughput genotyping of large populations at an affordable cost. Genotyping by sequencing (GBS), a reduced representation library sequencing method, allows highly multiplexed sequencing of genomic subsets. This method has limitations for small organisms with low amounts of genomic DNA, such as the bluetongue virus (BTV) vectors, Culicoides midges. This study employed the GBS method to isolate SNP markers de novo from whole genome amplified Culicoides brevitarsis genomic DNA. The individuals were collected from regions representing two different Australian patterns of BTV strain distribution: the Northern Territory (NT) and the east coast. We isolated 8145 SNPs using GBS. Phylogenetic analysis conducted using the filtered 3263 SNPs revealed the presence of a distinct C. brevitarsis sub-population in the NT and this was confirmed by analysis of mitochondrial DNA. Two loci showed a very strong signal for selection and were unique to the NT population. Bayesian analysis with STRUCTURE indicated a possible two-population cluster. The results suggest that genotyping vectors with high density markers in combination with biological and environmental data is useful. However, more extensive sampling over a wider spatial and temporal range is needed. The presence of sub-structure in populations and loci under natural selection indicates the need for further investigation of the role of vectors in shaping the two Australian systems of BTV transmission. The described workflow is transferable to genotyping of small, non-model organisms, including arthropod vectors of pathogens of economic and medical importance.
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Genotyping of whole genome amplified reduced representation libraries reveals a cryptic population of Culicoides brevitarsis in the Northern Territory, Australia
BMC Genomics, 2016Co-Authors: Maria G Onyango, Glenn A Bellis, Adrian Nicholas, Appolinaire Djikeng, Steve Kemp, Nicola C Aitken, Cameron Jack, Aaron Chuah, James Oguya, Peter J WalkerAbstract:Background The advent of genotyping by Next Generation Sequencing has enabled rapid discovery of thousands of single nucleotide polymorphism (SNP) markers and high throughput genotyping of large populations at an affordable cost. Genotyping by sequencing (GBS), a reduced representation library sequencing method, allows highly multiplexed sequencing of genomic subsets. This method has limitations for small organisms with low amounts of genomic DNA, such as the bluetongue virus (BTV) vectors, Culicoides midges. Results This study employed the GBS method to isolate SNP markers de novo from whole genome amplified Culicoides brevitarsis genomic DNA. The individuals were collected from regions representing two different Australian patterns of BTV strain distribution: the Northern Territory (NT) and the east coast. We isolated 8145 SNPs using GBS. Phylogenetic analysis conducted using the filtered 3263 SNPs revealed the presence of a distinct C. brevitarsis sub-population in the NT and this was confirmed by analysis of mitochondrial DNA. Two loci showed a very strong signal for selection and were unique to the NT population. Bayesian analysis with STRUCTURE indicated a possible two-population cluster. Conclusions The results suggest that genotyping vectors with high density markers in combination with biological and environmental data is useful. However, more extensive sampling over a wider spatial and temporal range is needed. The presence of sub-structure in populations and loci under natural selection indicates the need for further investigation of the role of vectors in shaping the two Australian systems of BTV transmission. The described workflow is transferable to genotyping of small, non-model organisms, including arthropod vectors of pathogens of economic and medical importance.
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assessment of population genetic structure in the arbovirus vector midge Culicoides brevitarsis diptera ceratopogonidae using multi locus dna microsatellites
Veterinary Research, 2015Co-Authors: Glenn A Bellis, Maria G Onyango, Nigel W Beebe, David Gopurenko, Adrian Nicholas, Moses Ogugo, Appolinaire Djikeng, Steve KempAbstract:Bluetongue virus (BTV) is a major pathogen of ruminants that is transmitted by biting midges (Culicoides spp.). Australian BTV serotypes have origins in Asia and are distributed across the continent into two distinct episystems, one in the north and another in the east. Culicoides brevitarsis is the major vector of BTV in Australia and is distributed across the entire geographic range of the virus. Here, we describe the isolation and use of DNA microsatellites and gauge their ability to determine population genetic connectivity of C. brevitarsis within Australia and with countries to the north. Eleven DNA microsatellite markers were isolated using a novel genomic enrichment method and identified as useful for genetic analyses of sampled populations in Australia, northern Papua New Guinea (PNG) and Timor-Leste. Significant (P < 0.05) population genetic subdivision was observed between all paired regions, though the highest levels of genetic sub-division involved pair-wise tests with PNG (PNG vs. Australia (FST = 0.120) and PNG vs. Timor-Leste (FST = 0.095)). Analysis of multi-locus allelic distributions using STRUCTURE identified a most probable two-cluster population model, which separated PNG specimens from a cluster containing specimens from Timor-Leste and Australia. The source of incursions of this species in Australia is more likely to be Timor-Leste than PNG. Future incursions of BTV positive C. brevitarsis into Australia may be genetically identified to their source populations using these microsatellite loci. The vector’s panmictic genetic structure within Australia cannot explain the differential geographic distribution of BTV serotypes.
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Light trapping of biting midges Culicoides spp. (Diptera: Ceratopogonidae) with green light-emitting diodes
Australian Journal of Entomology, 2006Co-Authors: A L Bishop, H J Mckenzie, Lorraine J Spohr, Glenn A Bellis, Anne M Harris, Ross Worrall, Lorna MelvilleAbstract:A study of responses by Culicoides spp. to light traps with light-emitting diodes (LEDs) confirmed that the livestock virus vector, Culicoides brevitarsis Kieffer, was preferentially attracted to green light. Four species shown previously to respond to blue light exhibited significantly higher responses to ultraviolet (UV) light. Field trials comparing green LEDs with incandescent lights in New South Wales, Northern Territory and East Timor confirmed the superiority of green LEDs for catching C. brevitarsis. The green LED traps also had a significant advantage over incandescent traps for a wide range of Culicoides species. These included: species whose ultimate preference was for UV, most species that are proven or potential vectors of viruses affecting Australian livestock and native animals and the main species affecting humans in northern Australia. Use of green LEDs has been adopted for trapping C. brevitarsis, especially in its marginal and low-density areas, and for detecting incursions of new Culicoides spp. into Australia. Use could be possible for species in other insect Orders.
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Protection of cattle from Culicoides spp. in Australia by shelter and chemical treatments.
Veterinaria Italiana, 2004Co-Authors: Doherty Wm, A L Bishop, Glenn A Bellis, Lorna Melville, Johnson Sj, Hunt NtAbstract:Summary Trials were conducted in three regions of Australia to investigate the potential for improvised shelters and chemical treatments to reduce feeding by Culicoides on cattle and thereby minimise the risk of bluetongue transmission during transport of cattle to ports. Various designs and combinations of roofs and walls were placed around penned cattle. Chemical treatments were applied to other penned cattle. Culicoides were collected from the cattle by vacuum samplers or by light traps in the pens. Roofs alone did not consistently reduce the numbers of Culicoides brevitarsis or C. fulvus and increased the numbers of C. actoni collected. Walls alone reduced the numbers of C. wadai but not C. brevitarsis. Roofs and walls in combination reduced the numbers of C. brevitarsis and C. wadai. The chemical treatments ‘Flyaway’ (a blend of repellents) and fenvalerate reduced the numbers of C. brevitarsis and C. wadai up to 52 h post treatment.