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Richard Wall - One of the best experts on this subject based on the ideXlab platform.
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Multiple resistance to macrocyclic lactones in the sheep scab mite Psoroptes ovis
Veterinary parasitology, 2019Co-Authors: Charlotte M Sturgess-osborne, Stewart T. G. Burgess, Sian Mitchell, Richard WallAbstract:Abstract The astigmatid mite Psoroptes ovis (Acari: Proroptidae) causes the highly contagious and debilitating ovine disease, sheep scab. This ectoparasitic infection has a high economic and animal welfare impact on British sheep farming. Following recent work demonstrating resistance of Psoroptes mites to moxidectin, a widely used macrocyclic lactone (ML) treatment for scab, the current study compared the toxicity of three of the commonly administered macrocylic lactone therapeutic treatments (moxidectin, ivermectin and doramectin) to P. ovis from outbreak populations that had appeared unresponsive to treatment. These outbreak populations were from Wales and south west England. The data presented demonstrate that there is resistance to all three available ML compounds in populations of Psoroptes mites. However, considerable variation in response suggested that resistance alone was not responsible for the reported lack of efficacy in all of the submitted cases; lack of response in others may be associated with inappropriate treatment application or management. These data highlight the importance of the appropriate use of these compounds to manage national scab incidence at levels that are consistent with acceptable animal welfare standards, while attempting to reduce the development and spread of resistance.
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Taxonomic priority in Psoroptes mange mites: P. ovis or P. equi?
Experimental & Applied Acarology, 2006Co-Authors: Richard Wall, Karin KolbeAbstract:The taxonomic priority of Psoroptes mange mites (Acari: Psoroptidae) is reviewed and the original species descriptions re-examined. The question of whether the name Psoroptes equi or Psoroptes ovis has priority has importance with respect to the descriptions used in any legislation required for compulsory treatment of infested animals. It is concluded that in the work by Hering [(1838) Nova Acta Physico-Medica Acadamiae Caesareae Leopoldino-Carolinae Naturae Curiosorum . Tomi 18, Pars 2, Vratislaviae und Bonn], which is generally assumed to present the type description, the first Psoroptes mite described is P. ovis , and that P. ovis (Hering 1838) should therefore, carry taxonomic priority for the synonomised genus.
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Isolation of Psoroptes scab mite microsatellite markers (Acari: Psoroptidae)
Molecular Ecology Notes, 2003Co-Authors: Lucie M. Evans, Deborah A. Dawson, Richard Wall, Terry Burke, Jamie R. StevensAbstract:Nine microsatellite markers have been isolated from the scab mite, Psoroptes ovis . These markers have been tested for polymorphism in individual Psoroptes mites originating from two hosts, the European rabbit, Oryctolagus cuniculus , and sheep, Ovis aries . No definitive picture of Psoroptes species’ status or interrelationships exists. This study provides the basis for a new molecular system to elucidate the systematics of groupings within the genus Psoroptes , allowing us to clarify the population dynamics and epidemiology of the mites causing sheep scab world wide.
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The effects of temperature and humidity on the off-host survival of Psoroptes ovis and Psoroptes cuniculi.
Veterinary Parasitology, 1999Co-Authors: Ke Smith, Richard Wall, E Berriatua, Nigel P. FrenchAbstract:Abstract The effects of both temperature and humidity on the survival of the mites Psoroptes ovis and Psoroptes cuniculi were considered in laboratory assays. When P. ovis and P. cuniculi were maintained at 95% humidity, maximum survival decreased linearly with increasing temperature, from approximately 15 days at 9°C to 5 days at 30°C. There was no significant difference between P. ovis and P. cuniculi in the effects of temperature on maximum survival. Adult male P. ovis and P. cuniculi had lower mean maximum survival than any of the other life cycle stages. There was a small but significant effect of humidity on survival for P. cuniculi ; LT 50 values were greater at 75–85% r.h. than at 55–65% r.h. The influence of off-host survival and the infestation of naive sheep from mites in the environment on the epidemiology of sheep scab are discussed.
Fernando Iván Flores-pérez - One of the best experts on this subject based on the ideXlab platform.
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Acaricidal effect and histological damage induced by Bacillus thuringiensis protein extracts on the mite Psoroptes cuniculi.
Parasites & vectors, 2015Co-Authors: Emmanuel Dunstand-guzmán, Guadalupe Peña-chora, Claudia Hallal-calleros, Mario Pérez-martínez, Víctor Manuel Hernández-velázquez, Jorge Morales-montor, Fernando Iván Flores-pérezAbstract:Background The mite Psoroptes cuniculi is a common worldwide ectoparasite and the most frequently found in rabbit farms. It causes significant economic losses on commercial rabbit breeding associated with poor leather quality, reduced conception rates, weight loss, poor growth and death. Several strategies have been proposed for the treatment of mange caused by this mite, ranging from the use of acaricides, entomopathogenic fungi, essential oils and vaccines. However, therapy and control of both human scabies and animal mange are still based mainly on the use of drugs and chemicals such as ivermectin, which involves disadvantages including genotoxic and cytotoxic effects, resistance and environmental damage. Bacillus thuringiensis is a bacterium, innocuous for human being, domestic animals and plants that produces highly biodegradable proteins, and has been used worldwide for biological control. The aim of this work was to find an alternative treatment based on biological control for scabies caused by Psoroptes cuniculi, using protein extracts from strains of Bacillus thuringiensis.
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Acaricidal effect and histological damage induced by Bacillus thuringiensis protein extracts on the mite Psoroptes cuniculi
Parasites & Vectors, 2015Co-Authors: Emmanuel Dunstand-guzmán, Guadalupe Peña-chora, Claudia Hallal-calleros, Mario Pérez-martínez, Víctor Manuel Hernández-velázquez, Jorge Morales-montor, Fernando Iván Flores-pérezAbstract:Background The mite Psoroptes cuniculi is a common worldwide ectoparasite and the most frequently found in rabbit farms. It causes significant economic losses on commercial rabbit breeding associated with poor leather quality, reduced conception rates, weight loss, poor growth and death. Several strategies have been proposed for the treatment of mange caused by this mite, ranging from the use of acaricides, entomopathogenic fungi, essential oils and vaccines. However, therapy and control of both human scabies and animal mange are still based mainly on the use of drugs and chemicals such as ivermectin, which involves disadvantages including genotoxic and cytotoxic effects, resistance and environmental damage. Bacillus thuringiensis is a bacterium, innocuous for human being, domestic animals and plants that produces highly biodegradable proteins, and has been used worldwide for biological control. The aim of this work was to find an alternative treatment based on biological control for scabies caused by Psoroptes cuniculi , using protein extracts from strains of Bacillus thuringiensis . Methods P. cuniculi mites were obtained from naturally infected New Zealand rabbits, and different doses of protein from B. thuringiensis were added to the mites. We measured mortality and obtained the median lethal concentration and median lethal times. For histological analysis, the mites were fixed in 10 % formalin, processed according to the paraffin embedded tissue technique. Sections were stained with hematoxylin-eosin to observe the general histological structure. Results We report here for the first time evidence about the in vitro acaricidal effect caused by the strain GP532 of B. thuringiensis on the mite Psoroptes cuniculi , with an LC_50 of 1.3 mg/ml and a LT_50 of 68 h. Histological alterations caused by B. thuringiensis on this mite, included the presence of dilated intercellular spaces in the basal membrane, membrane detachment of the peritrophic matrix and morphological alterations in columnar cells of the intestine. Conclusions Since this mite is an obligate ectoparasite that affects rabbits, goats, horses, cows and sheep, B. thuringiensis protein extracts are proposed as a potential treatment for biological control of mange in farm animals.
Bertrand Losson - One of the best experts on this subject based on the ideXlab platform.
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Failure of injectable ivermectin to control psoroptic mange in cattle
The Veterinary record, 2010Co-Authors: Mireille Lekimme, Frédéric Farnir, Françoise Maréchal, Bertrand LossonAbstract:PSOROPTIC mange is a severe, debilitating skin condition affecting sheep, goats, rabbits, horses and cattle ([Soulsby 1982][1]). The causative mite, Psoroptes ovis , lives on the skin of the host, producing intense irritation ([Berriatua and others 2001][2]) that leads to marked economic losses and
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In vitro entomopathogenic activity of Beauveria bassiana against Psoroptes spp. (Acari: Psoroptidae).
Veterinary parasitology, 2006Co-Authors: Mireille Lekimme, B Mignon, S Tombeux, C Focant, F Maréchal, Bertrand LossonAbstract:An indigenous strain (IHEM 18747) of Beauveria bassiana (Balsamo) Vuillemin (Deuteromycetes) was evaluated for its in vitro entomopathogenic activity against the parasitic mite Psoroptes ovis Hering (Acari: Psoroptidae) from rabbits. The following aspects were evaluated: (1) effects of conidial concentration on the viability of adult females; (2) influence of the infection on the fertility, and on the hatchability of eggs; (3) and transmission of infection between mites, and from contaminated surface. Adult females immersed into increasing concentrations of conidia (10(4)-10(9)conidia ml(-1)) showed a dose-related susceptibility. At the highest concentration of conidia, LT50 was 1.6 days while LT50 of the controls reached 5.8 days. The fungus was able to sporulate on the body surface and 100% of the mites were covered with mycelium after immersion in solutions containing 10(7)-10(9)conidia ml(-1). One hundred percent of healthy mites exposed to infected cadavers or surfaces acquired the infection (LT50 reached 1.9 and 1.73 days, respectively, versus 6.1 and 5.1 days in controls, respectively). Egg laying was not reduced by the fungal infection but both the hatchability of the eggs and the life span of the emerging larvae were significantly reduced. Eggs directly infected with the fungus did not show reduced hatchability but the life span of the larvae was shortened. It is concluded that B. bassiana has a high entomopathogenic activity against Psoroptes spp. The in vivo use of this biocontrol agent against Psoroptes spp. in rabbit, sheep and cattle deserves further attention.
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In vitro tests for evaluation of the hatchability of the eggs of Psoroptes mites following exposure to acaricidal compounds
Medical and veterinary entomology, 2006Co-Authors: Mireille Lekimme, Françoise Maréchal, Bernard Mignon, T. Leclipteux, Sabrina Tombeux, Bertrand LossonAbstract:. Three in vitro assays for the evaluation of the hatchability of the eggs of the mite Psoroptes ovis (Hering) (Acari: Psoroptidae) are described. Preliminary trials showed that hatching occurs at very high rates when eggs are incubated under conditions of high humidity, on a liquid medium and in agarose dishes. These three protocols were compared, taking into account the ease of preparation, follow-up and accuracy of counting. The best protocol was found to be the use of agarose dishes. It was accurate, easy to carry out and reproducible for further evaluation of existing or potentially new compounds against both adults and eggs of Psoroptes spp. The acaricidal properties of phoxim and amitraz were then evaluated against eggs and adults using the three protocols. Results showed that for both drugs, in vitro adulticidal activity was complete, whereas the in vitro ovicidal activity was only partial. Nevertheless, efficacy of amitraz against both adults and eggs was shown to be higher than that of phoxim.
Guangyou Yang - One of the best experts on this subject based on the ideXlab platform.
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Beauveria bassiana is a potential effective biological agent against Psoroptes ovis var. cuniculi mites
Biological Control, 2019Co-Authors: An Jiang, Yuan Yuan, Rui Yang, Na Zhang, Yue Xie, Weiming Lai, Peng Xuerong, Guangyou YangAbstract:Abstract Beauveria bassiana is an entomopathogenic fungus known for its high efficacy against many agricultural insect pests, and is considered to be safe to the environment. Previous studies showed that B. bassiana is also capable of infection and horizontal transmission between Psoroptes ovis mites, but we still lack information on the clinical efficacy of B. bassiana against P. ovis. In this study, we evaluated the acaricidal efficacy of B. bassiana against Psoroptes ovis var. cuniculi, both in vitro and in vivo. Tests consistently showed that B. bassiana caused high mortality against P. ovis var. cuniculi in vitro with dose- and time-dependent susceptibility responses; applying 4.26 × 109 conidia/ml resulted in 100% mortality of P. ovis var. cuniculi within 9 days with an LT50 of 2.50. In vivo, rabbits infected with P. ovis var. cuniculi that were treated with 4.26 × 109 conidia/ml B. bassiana fungal suspension showed a 100% therapeutic response 3 days later, an efficacy greater than that of the anti-parasitic drug ivermectin. Moreover, no rabbits treated with B. bassiana showed symptoms of disease recurrence by 60 days post-treatment. Taken together, these results show that B. bassiana has high efficacy against P. ovis var. cuniculi; hence, it may be a potentially effective biological insecticide for use against psoroptic mange.
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In vitro acaricidal activity of extracts from 16 traditional Chinese medicines against Psoroptes ovis var. cuniculi
International Journal of Acarology, 2017Co-Authors: Yuqing Liang, Xuerong Peng, Cheng Guo, Chun-lin Fang, Guangyou YangAbstract:The in vitro acaricidal activities of 16 different traditional Chinese medicines against Psoroptes ovis var. cuniculi were evaluated using extracts prepared by water decocting and ethanol thermal c...
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the complete mitochondrial genome of the scab mite Psoroptes cuniculi arthropoda arachnida provides insights into acari phylogeny
Parasites & Vectors, 2014Co-Authors: Guohua Liu, Guangyou Yang, Huiqun Song, Tianyu Liu, Xingquan ZhuAbstract:Background Limited available sequence information has greatly impeded population genetics, phylogenetics and systematics studies in the subclass Acari (mites and ticks). Mitochondrial (mt) DNA is well known to provide genetic markers for investigations in these areas, but complete mt genomic data have been lacking for many Acari species. Herein, we present the complete mt genome of the scab mite Psoroptes cuniculi.
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Molecular taxonomic relationships of Psoroptes and Chorioptes mites from China based on COI and 18S rDNA gene sequences.
Veterinary Parasitology, 2012Co-Authors: Shuai Wang, Shuxian Wang, Xuerong Peng, Xiaobin Gu, Yan Fu, Guangyou YangAbstract:In this present study, the mitochondrial DNA gene cytochrome coxidase subunit I (COI) and the small subunit ribosomal RNA (18S rDNA) gene were used to determine the taxonomic relationships of Psoroptes and Chorioptes mites from China. The neighbor-joining and maximum-parasimony approach were used to evaluate the evolutionary relatedness among different hosts in the genera Psoroptes and Chorioptes. Phylogenetic analysis showed that Psoroptes cuniculi and Psoroptes natalensis may be two different species within the genus Psoroptes, and Chorioptes texanus and Chorioptes panda are different species within the genus Chorioptes.
Walter M. Boyce - One of the best experts on this subject based on the ideXlab platform.
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Phylogeny and Host Specificity of Psoroptic Mange Mites (Acarina: Psoroptidae) as Indicated by ITS Sequence Data
Journal of medical entomology, 2000Co-Authors: Rob Roy Ramey, Walter M. Boyce, Scott T. Kelley, Brian Dorsey FarrellAbstract:We used molecular phylogenetic techniques to study the systematic relationships and host specificity of Psoroptes mange mites, which are pests of numerous domestic and wild ungulates. Phylogenetic analysis of DNA sequence data from the internal transcribed spacer region 1 (ITS1) of nuclear ribosomal DNA indicated that populations of Psoroptes are not host specific. Furthermore, the currently used taxonomy of Psoroptes is not concordant with the phylogeny derived from ITS1. During the course of the study, we discovered apparent paralogous ITS sequences within individual mites as a result of varying polymerase chain reaction reaction conditions. This finding concords with other studies of ITS and suggests a cautious approach when interpreting data from ITS sequences. Host DNA contamination was also found to be a significant problem in data collection, and we report on the development of methods to overcome the problems of contamination in parasitic mites.
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Pathogen Exposure Patterns among Sympatric Populations of Bighorn Sheep, Mule Deer and Cattle
Journal of wildlife diseases, 1997Co-Authors: Randall S. Singer, David A. Jessup, Ian A. Gardner, Walter M. BoyceAbstract:We sampled sympatric bighorn sheep (Ovis canadensis, n = 31), mule deer (Odocoileus hemionus, n = 38), and domestic cattle (n = 26) in the San Bernadino Mountains of southern California (USA) for the presence of Psoroptes spp. mites and for serologic evidence of exposure to bluetongue virus (BTV) and Babesia spp. From 1991 through 1994, Psoroptes spp. infestations were found on 12 (44%) of 27 bighorn sheep. No mites were found on mule deer or cattle. The BTV serum antibody prevalence in a cohort of 26 cattle ranged from 17 to 89%. There was no evidence of exposure to BTV in the bighorn sheep or mule deer. The cumulative serum antibody prevalence of Babesia spp. during the study was 35% in 26 bighorn sheep and 85% in 20 mule deer, while antibodies were not detected in a cohort of cattle when they were sampled in May (n = 23) and December (n = 22) of 1992. Based on these results, we concluded that infestation with Psoroptes spp. and exposure to BTV was limited to bighorn sheep and cattle, respectively. In contrast, Babesia spp. infections appeared to be common in both mule deer and bighorn sheep while there was no evidence of exposure in cattle.
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Antibody Responses to Psoroptes sp. Mites in Dall Sheep (Ovis dalli)
Journal of wildlife diseases, 1996Co-Authors: Walter M. Boyce, Randall L. ZarnkeAbstract:We determined that antibody responses to Psoroptes sp. mites were not present in 403 of 407 sera samples collected opportunistically from 1979 through 1991 from Dall sheep (Ovis dalli) from five locations in Alaska, USA (Eastern Arctic, n = 61; Central Arctic, n = 15; Western Interior, n = 122; Central Interior, n = 63; Eastern Interior, n = 146). Test values for four samples exceeded the positive cutoff value for the immunoassay, but exposure to mites could not be confirmed since the 95% confidence interval for true prevalence ranged from 0 to 2.3%. Therefore, we concluded that these were probably false positive results. Our analysis, coupled with the lack of previous reports of mites or lesions in Dall sheep or other Alaskan ungulates, provided indirect evidence that Psoroptes sp. are not enzootic in Dall sheep in Alaska. In contrast, Psoroptes sp. have been reported in bighorn sheep (Ovis canadensis) and other wild ungulate populations from southern Canada to Mexico. These findings are compatible with ...
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Seroprevalence of Psoroptes sp. mites in free-ranging elk (Cervus elaphus) as determined by kinetic ELISA.
Journal of wildlife diseases, 1996Co-Authors: Michael H. Ziccardi, Walter M. Boyce, Ian A. GardnerAbstract:Western blots and a kinetic enzyme-linked immunosorbent assay (ELISA) were used to characterize and quantify the prevalence of antibodies to Psoroptes sp. mites in elk (Cervus elaphus) from nine herds in North America. Sera from infested (n =18) and non-infested (n = 22) elk were used to optimize test methodology and to define cut-off values for negative, suspect, and positive samples. Among 357 samples, 35 (9.8%) of the animals were seropositive, 259 (73%) were negative, and 63 (18%) were suspect. Six of nine herds (67%) contained positive animals and two additional herds (22%) had suspect animals. Sex was not associated with prevalence of antibodies, but adults greater than 2 yr old were approximately five times more likely (95% confidence interval = 2.6–15.4) to be seropositive than calves. Based on these results, we propose that exposure to Psoroptes sp. mites may be widespread in free-ranging elk of North America.
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EXPOSURE TO Psoroptes SP. MITES IS COMMON AMONG BIGHORN SHEEP (OVIS CANADENSIS) POPULATIONS IN CALIFORNIA
Journal of wildlife diseases, 1992Co-Authors: Jonna A. K. Mazet, Ian A. Gardner, Walter M. Boyce, Richard K. Clark, Jay Mellies, David A. JessupAbstract:Sera (n = 806) from 50 populations of bighorn sheep (Ovis canadensis) in California (USA) were evaluated for antibodies to Psoroptes sp. mites using a kinetic enzyme-linked immunosorbent assay (ELISA). Test values for each sample were determined to be either positive or negative at each of two ELISA cutoff values that provided either 100% sensitivity (low cutoff) or 100% specificity (high cutoff), respectively. One hundred sixty-eight (20.8%) sera were seropositive at the low cutoff value, and 87 (10.8%) of these sera also were seropositive at the high cutoff value. Eleven populations were designated as scabies-suspect and 25 populations were designated as scabies-positive because they had at least one seropositive animal at the low and the high cutoff values, respectively. Based on these results, exposure to Psoroptes sp. mites appeared to be widely distributed among bighorn sheep populations from 1980 to 1990 and infested animals may have been present prior to 1980.
