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Dong Zhang - One of the best experts on this subject based on the ideXlab platform.
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spatial distribution of Gasterophilus pecorum diptera eggs in the desert steppe of the kalamaili nature reserve xinjiang china
BMC Ecology and Evolution, 2021Co-Authors: Heqing Huang, Make Ente, Ke Zhang, Changliang Shao, Chen Wang, Zhenbiao Wang, Dong ZhangAbstract:BACKGROUND The dominant Gasterophilus species in the desert steppe (Xinjiang, China) Gasterophilus pecorum poses a serious threat to the reintroduced Przewalski's horses. We investigated the distribution pattern of G. pecorum eggs in June 2017. METHODS Two sampling methods, transect and grid, were used, and the results were analyzed via geostatistics by semivariance. The nest quadrat was used to determine the optimal quadrat size. RESULTS Eggs were found in 99 quadrats (63.1%) and 187 clusters (1.5%) of Stipa caucasica on the steppe. The mean oviposition count of a cluster was 3.8 ± 1.6. Three-eggs is the mode of which females oviposit on each ovigerous S. caucasica (22.0%). Semivariogram analysis revealed that the distance of spatial dependence for eggs was 921 m, 1233 m and 1097 m for transect 1, transect 2 and grid methods, respectively, while spatial continuity was 62%, 77% and 57.0% for transect 1, transect 2 and grid, respectively. The eggs showed a patchy, aggregated distribution pattern. This suggested the spherical model is most applicable. The proportion of ovigerous S. caucasica was significantly correlated with the distance from water resources (r = - 0.382, p = 0). CONCLUSION Our findings indicated that diversification of G. pecorum oviposition was a new adaptative strategy for its survival in the desert steppe ecological niche. This made it more efficient at infecting hosts in the local environment. Areas surrounding water resources, especially around the drinking paths of equids (500 m radius surrounding the water), were concentrated epidemic areas. It is suggested that more attention to be paid to the ecological characteristics of G. pecorum in order to develop control measures that would reduce the infection risk for Przewalski's horses.
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taxonomic review of Gasterophilus oestridae gasterophilinae of the world with updated nomenclature keys biological notes and distributions
ZooKeys, 2019Co-Authors: Thomas Pape, Dong ZhangAbstract:A taxonomic review of Gasterophilus is presented, with nine valid species, 51 synonyms and misspellings for the genus and the species, updated diagnoses, worldwide distributions, and a summary of biological information for all species. Identification keys for adults and eggs are elaborated, based on a series of new diagnostic features and supported by high resolution photographs for adults. The genus is shown to have its highest species richness in China and South Africa, with seven species recorded, followed by Mongolia, Senegal, and Ukraine, with six species recorded.
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Gasterophilus flavipes oestridae gasterophilinae a horse stomach bot fly brought back from oblivion with morphological and molecular evidence
PLOS ONE, 2019Co-Authors: Thomas Pape, Dong ZhangAbstract:Species of Gasterophilus Leach are obligate parasites in domestic and wild equids and responsible for cosmopolitan gasterophilosis. Although with only eight species known so far, they have received considerable attention because of their significant veterinary and economic importance. Surprisingly, we found that G. flavipes (Olivier) is a valid species based on morphological characters from male, female and the egg, after spending half a century as a synonym of G. haemorrhoidalis (Linnaeus). In the present study, G. flavipes, G. haemorrhoidalis and G. inermis (Brauer), which are the three closely related species possessing a remarkable mixture of shared morphological characters, are diagnosed and comparatively redescribed; the key to separate adults and eggs are provided, together with a series of high-resolution photographs from all the body parts. COI barcodes do not allow for a separation of G. flavipes, G. haemorrhoidalis and G. inermis, but showed a closer relationship between G. flavipes and G. haemorrhoidalis than the other two combinations, which is consistent with the morphological evidence. Geographically, G. flavipes seems to be common and widespread in the warmer parts of the Palaearctic region. Thus, the epidemiology of gasterophilosis where G. flavipes is known or supposed to occur calls for a more careful veterinarian re-assessment. A decline in the populations of Gasterophilus spp. has been noticed in Europe, but all seven Palaearctic species of Gasterophilus appear to maintain stable populations in Xinjiang (China), which may be explained by a higher biodiversity of equids and less use of anti-parasitic treatments in Xinjiang than in Europe. Our study shows that morphological characters still provide the solid backbone in classification of Gasterophilus at species-level, and updated diagnoses and a key is provided to distinguish G. flavipes, G. haemorrhoidalis and G. inermis, and to facilitate studies of epidemiology, phylogeny and host-parasite co-evolution.
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molecular and morphological characterization of third instar palaearctic horse stomach bot fly larvae oestridae gasterophilinae Gasterophilus
Veterinary Parasitology, 2018Co-Authors: Yiou Chen, Qike Wang, Thomas Pape, Dong ZhangAbstract:Species of Gasterophilus are obligate parasites of equids and may induce severe, even lethal myiasis. However, identification of the third instar Gasterophilus larva at the species level is still problematic predominantly due to a shortage of diagnostic morphological features and incomplete molecular libraries. Testing the suitability of three different molecular markers showed that the traditional 650 bp barcode region near the 5' terminus of the cytochrome c oxidase subunit I (COI) served as a better tool for species-level identification than a 663 bp region near the 3' terminus of COI and a 554 bp region near the 5' terminus of the large subunit ribosomal RNA. We found that barcoding discriminates G. intestinalis, G. nasalis, G. nigricornis and G. pecorum but not G. haemorrhoidalis and G. inermis. A comparative morphological study using scanning electron microscopy was conducted to promote the identification of the third instar larvae. Photographs of fresh mature third instar larvae are provided for all species, and the remarkable green body colour of third instar G. nigricornis is fully documented for the first time. Two morphological keys are provided, one is suitable for quick identification, and the other based on ultrastructural details is provided for further comparative morphological investigation. A new term 'oral plate' instead of 'mandible' was proposed for a pair of sclerites of uncertain homology emerging from the secondary mouth opening. Our data shows that DNA barcodes cannot replace morphology for identification of third instars of Gasterophilus species, and a scaffold is provided for an integrated taxonomic reference system, which will contribute to monitoring gasterophilosis for equid welfare and protection, and also facilitate further studies in functional anatomy, phylogenetic analyses and host-parasite co-evolutionary investigations of Gasterophilus.
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genetic diversity of common Gasterophilus spp from distinct habitats in china
Parasites & Vectors, 2018Co-Authors: Boru Zhang, Heqing Huang, Haoyu Wang, Dong Zhang, Hongjun Chu, Make EnteAbstract:Gasterophilus species are widely distributed around the world. The larvae of these flies parasitize the digestive tract of equids and cause damage, hindering horse breeding and protection of endangered species. However, study of the genetic structure of geographically distinct Gasterophilus populations is lacking. Here, we analyzed the genetic diversity of Gasterophilus pecorum, G. intestinalis, G. nasalis and G. nigricornis from three typical grasslands (meadow, desert and alpine steppes) in China as compared to published sequences from Italy, Poland and China (Daqing and Yili), based on the mitochondrial cytochrome c oxidase cox1 and cox2 gene sequences. Haplotype diversity and nucleotide diversity of mitochondrial genes was generally high in all Gasterophilus populations. Due to the unique natural climatic conditions of the alpine steppe, there were high levels of genetic differentiation among different geographical populations of G. pecorum and G. nasalis, indicating that environmental variations influenced population genetic structure. Frequent exchanges between meadow and desert steppe Gasterophilus species resulted in low genetic differentiation. The highest exchange rates were found among G. intestinalis populations. Genetic differentiation was only observed on a large geographical scale, which was confirmed by analyzing population genetic structure. Three species, G. pecorum, G. intestinalis and G. nasalis, from meadow steppe showed a high emigration rate, indicating that the direction of Gasterophilus dispersal in China was from east to west. Our results show that the four Gasterophilus species have a high level of genetic diversity and different degrees of genetic differentiation and gene flow among different populations of the same species, reflecting their potential to adapt to the environment and the environmental impact on genetic structure. Knowledge of the genetic structure, population history, and migration will help understand the occurrence and prevalence of gasterophilosis and provide a basis for controlling the local spread of Gasterophilus spp.
M C Cogley - One of the best experts on this subject based on the ideXlab platform.
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use of detomidine hydrochloride as an adjunct for studying first stage Gasterophilus intestinalis diptera gasterophilidae in the tongue of the horse
Veterinary Parasitology, 2000Co-Authors: T P Cogley, M C CogleyAbstract:Abstract A synthetic α-2 adrenergic agonist, detomidine hydrochloride, was used in the study of in vivo activity of Gasterophilus intestinalis (Diptera: Gasterophilidae) during migration in the tongue of the horse. Use of the drug allowed the investigator to manipulate the tongue and closely observe the movement patterns and tissue disturbance caused by burrowing first-stage larvae. Detomidine hydrochloride should be utilized in studies of drug efficacy and larval biology, whenever possible, to avoid the need to sacrifice the horse.
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inter relationship between Gasterophilus larvae and the horse s gastric and duodenal wall with special reference to penetration
Veterinary Parasitology, 1999Co-Authors: T P Cogley, M C CogleyAbstract:Abstract The degree of penetration into the stomach and duodenum of the horse by bot fly larvae, Gasterophilus intestinalis (De Geer) and G . nasalis (Linnaeus) (Diptera : Gasterophilidae) was evaluated. Evidence of larval perforation of the stomach or duodenum was not found on gross inspection. Palpation of the intact stomach and duodenum was not effective in establishing the existence of Gasterophilus larvae within the organs. Findings suggest that larvae of both species produce an ulcer of similar depth within the gastrointestinal wall. The ulcer depth produced by larvae did not correlate with the normal, unaffected thickness of the particular stomach or duodenum. Tissue proliferation beneath ulcers of the stomach and duodenum was not correlated with the depth of the ulcer. Proliferation of the tissue beneath the ulcers of the stomach generally exceeded that found under duodenal ulcers. Gastric wall beneath the G . intestinalis ulcer frequently attained a thickness equal to or greater than the normal stomach wall. Histopathological examinations below the ulcer revealed intense fibrosis. Duodenal thickness below the G. nasalis ulcer was typically less than normal and resulted in an attenuated wall. Histopathological analysis of the affected duodenum revealed severe loss of submucosal glands in a sharply demarcated area below and surrounding the lesion. Fibrosis of the underlying lamina propria mucosae and tunica submucosa was appreciable but failed to restore the original thickness of the duodenal wall. Host tissue response and moderation of the parasite’s behavior reduce the chances of direct perforation of the gastrointestinal tissue.
Douglas D. Colwell - One of the best experts on this subject based on the ideXlab platform.
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species composition of Gasterophilus spp diptera oestridae causing equine gastric myiasis in southern italy parasite biodiversity and risks for extinction
Veterinary Parasitology, 2005Co-Authors: Domenico Otranto, Piermarino Milillo, Gioia Capelli, Douglas D. ColwellAbstract:Horse gastrointestinal myiasis caused by larvae of Gasterophilus spp. (Diptera, Oestridae) flies has a worldwide distribution and, where present, it is primarily caused by larvae of Gasterophilus intestinalis and Gasterophilus nasalis. Other species, i.e., Gasterophilus inermis, Gasterophilus pecorum and Gasterophilus haemorrhoidalis, present in different or in the same regions of the gastrointestinal tract, were only occasionally reported in very limited areas of eastern European Countries and in central Italy. With the aim to contribute data on the species composition of Gasterophilus and on the seasonal variation of the infection pattern in southern Italy, 152 native horses were necropsied from January to December 2003 and Gasterophilus larvae were collected from the stomach, the small intestine and the rectum of each of them. On the whole, 125 (82.2%) horses were infected by larvae of Gasterophilus spp. and 214 second stage larvae (L2) and 13,342 third stage larvae (L3) collected. Five species of Gasterophilus were identified with the following prevalence: G. intestinalis=95.2%, G. nasalis=44.8%, G. inermis=15.2%, G. pecorum=2.6% and G. haemorrhoidalis=0.8%. L3 were retrieved throughout the observation period with the highest mean burdens from January to August 2003 while the lowest mean was registered from September to November 2003. L2 were collected in February-March 2003 and from September to December 2003. The majority of the animals (n=66, 43.4%) were infected with a single Gasterophilus species, however, 45 animals (29.6%) harboured 2 species, 12 animals (7.9%) 3 species and 2 animals (1.3%) 4 species. The trend of abundance in the L3 of G. intestinalis and G. nasalis, the most represented species, was highly concordant (r=0.5, p<0.001). A retrospective comparison of our results and of other data from four seasons of observation (1983-1986) in central Italy showed that the number of G. inermis, G. pecorum and G. haemorrhoidalis have been decreasing relative to G. intestinalis and G. nasalis which may suggest tendency toward the extinction of the three former species of Gasterophilus.
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Cuticular sensilla on newly hatched larvae of Gasterophilus intestinalis and Oestrus ovis.
Medical and Veterinary Entomology, 1995Co-Authors: Douglas D. Colwell, Philip J SchollAbstract:. Cuticular sensilla on newly hatched larvae of Gasterophilus intestinalis De Geer (Diptera: Gasterophilidae) and Oestrus ovis (L.) were studied by scanning electron microscopy. Two types of trichoid sensilla, two types of coeloconic sensilla and a pit sensillum were present on the thoracic and abdominal segments of G. intestinalis larvae. Sensilla on larvae of O. ovis were similar although only one type of trichoid sensillum was present. Total number of sensilla were higher for O. ovis than for G. intestinalis (248 v. 214). Variation in numbers of sensilla is consistent with the concept that increasing numbers of sensilla are associated with increasingly complex searching behaviour required to locate suitable habitats for development.
T P Cogley - One of the best experts on this subject based on the ideXlab platform.
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use of detomidine hydrochloride as an adjunct for studying first stage Gasterophilus intestinalis diptera gasterophilidae in the tongue of the horse
Veterinary Parasitology, 2000Co-Authors: T P Cogley, M C CogleyAbstract:Abstract A synthetic α-2 adrenergic agonist, detomidine hydrochloride, was used in the study of in vivo activity of Gasterophilus intestinalis (Diptera: Gasterophilidae) during migration in the tongue of the horse. Use of the drug allowed the investigator to manipulate the tongue and closely observe the movement patterns and tissue disturbance caused by burrowing first-stage larvae. Detomidine hydrochloride should be utilized in studies of drug efficacy and larval biology, whenever possible, to avoid the need to sacrifice the horse.
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inter relationship between Gasterophilus larvae and the horse s gastric and duodenal wall with special reference to penetration
Veterinary Parasitology, 1999Co-Authors: T P Cogley, M C CogleyAbstract:Abstract The degree of penetration into the stomach and duodenum of the horse by bot fly larvae, Gasterophilus intestinalis (De Geer) and G . nasalis (Linnaeus) (Diptera : Gasterophilidae) was evaluated. Evidence of larval perforation of the stomach or duodenum was not found on gross inspection. Palpation of the intact stomach and duodenum was not effective in establishing the existence of Gasterophilus larvae within the organs. Findings suggest that larvae of both species produce an ulcer of similar depth within the gastrointestinal wall. The ulcer depth produced by larvae did not correlate with the normal, unaffected thickness of the particular stomach or duodenum. Tissue proliferation beneath ulcers of the stomach and duodenum was not correlated with the depth of the ulcer. Proliferation of the tissue beneath the ulcers of the stomach generally exceeded that found under duodenal ulcers. Gastric wall beneath the G . intestinalis ulcer frequently attained a thickness equal to or greater than the normal stomach wall. Histopathological examinations below the ulcer revealed intense fibrosis. Duodenal thickness below the G. nasalis ulcer was typically less than normal and resulted in an attenuated wall. Histopathological analysis of the affected duodenum revealed severe loss of submucosal glands in a sharply demarcated area below and surrounding the lesion. Fibrosis of the underlying lamina propria mucosae and tunica submucosa was appreciable but failed to restore the original thickness of the duodenal wall. Host tissue response and moderation of the parasite’s behavior reduce the chances of direct perforation of the gastrointestinal tissue.
L G Evangelista - One of the best experts on this subject based on the ideXlab platform.
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scanning electron microscope observations on third instar Gasterophilus nasalis diptera oestridae
Journal of Medical Entomology, 1999Co-Authors: Antonio Cesar Rios Leite, F B Scott, L G EvangelistaAbstract:Scanning electron microscope observations studied the morphology of 3rd-instar Gasterophilus nasalis (L.). Distinctive features are illustrated in a sequence of 16 micrographs, bearing indications of structures considered of special interest. The morphology of G. nasalis is compared with that of other larval bot flies.