Scab Mite Research Articles

Persistent activity and therapeutic efficacy of Delcid® 7.5 against scab mites (<i>Psoroptes ovis</i>) in sheep

The purpose of the research is to study persistent activity and therapeutic efficacy of Delcid® 7.5 against scab mites Psoroptes ovis in sheep.Materials and methods. The studies were performed in the Bukhty peasant farm enterprise in November 2021 on the Kizlyarsky District winter pastures in the Republic of Dagestan. Three groups of sheep were formed, of which two groups (second and third) had a confirmed clinical diagnosis of psoroptic mange (P. ovis) and one group (first) was free from scab mites. Sheep from the first and second groups were treated with Delcid at a dose of 10 ml of the drug per animal. After 10 days, sheep from the second group were treated with the drug repeatedly at the same dose. Sheep from the first and second groups were treated with the drug applied on dry and intact skin of the back along the spine using the drop method. The third control (infected) group of animals was not treated. All experimental groups of sheep were kept in a common flock. The Delcid persistent activity and thera-peutic efficacy were evaluated by clinical examination and microscopy of the skin for P. ovis mites before the experiment started and at 1, 3, 7, 10, 14, 21, 25 and 30 days after treatment in the first group and at 1, 3, 7, 11, 13, 17, 20, 24, 31, 35 and 40 days in the second and third groups of sheep.Results and discussion. It was found that Delcid 7.5 showed persistent activity in sheep against psoroptic mange pathogens for 21 days after a single treatment at a dose of 10 ml per animal. Delcid acaricidal effect after double treatment against P. ovis was 31 days.

In silico identification of neurohormones and neuropeptides and their G protein-coupled receptors in the sheep scab mite Psoroptes ovis: potential targets for alternative control strategies

ABSTRACT The genome of the sheep scab mite, Psoroptes ovis, was analysed for the presence of neuropeptide and neurohormone precursors and their G protein-coupled receptors (GPCRs). Many of these showed significant similarities to those known or predicted from other Acaridae and also insect species. Similarities to orthologous precursors and receptors from the sheep Ovis aries, host for P. ovis, were also evaluated. The roles of neuropeptides and neurohormones in the control of behavioural and physiological processes such as osmoregulation, reproduction, growth and development are discussed. The GPCRs for these neuropeptides and neurohormones offer potential targets for the development of next-generation acaricides. Modification of normal receptor function by new chemistries that either block or over-stimulate the GPCRs can result in the death of the mite or alter its normal development and reproductive ability thereby suppressing populations. This work provides the information required to select potential GPCR targets in P. ovis for future development of new acaricides.

What’s scabies?

Scabies is a contagious skin infestation caused by a parasite. In its usual, common form scabies is passed on through long-time close physical contact. Though rarely so, infestation, of the profuse and hyperkeratotic form, can also be caused by shared clothes, shared bed or bathroom linen. Scabies causative agent is the female mite sarcoptes scabiei , also called scab mites, a small-size skin parasite, less than half a millimeter in length, of the larger family of mites. It burrows into the host’s upper skin layer to lay its eggs there. Scabies is a common skin disorder throughout the world. Anyone can get infested whatever their age, sex, social background, or personal body care. Regular episodes of scabies flare up as small scales epidemics in communities like schools, nurseries, retirement homes, inpatient services, &.

Pesticide dose adjustment in fruit and grapevine orchards by DOSA3D: Fundamentals of the system and on-farm validation

Agricultural productivity cannot be sustained without the application of plant protection measures. Within the framework of integrated pest management (IPM), the use of chemical pesticides should be limited to the last option among the available practices. Even though their use remains common, it carries associated environmental and human health risks. One of the most accepted practices within IPM is the reduction of spraying events and/or pesticide applied doses. DOSA3D is a decision support system that allows the dose to be adjusted to the specific treatment scenario. For this, DOSA3D calculates the optimal application volume rate by estimating the leaf area index and takes into account the overall spraying efficiency and the pest or disease to be controlled. The system adopts specific minimum volume rates for fruit trees and vineyards without compromising the crop health status. To establish the adjusted dose, the labeled or the adviser prescription concentration is kept. Resulting adjusted doses provided by DOSA3D achieved pesticide savings up to 53% in fruit trees and 60% in vineyards. DOSA3D has been validated against the main diseases and pests of fruit trees and vineyards: brown spot and psylla in pear orchards; alternaria blotch disease, apple scab, codling moth, oriental moth and red spider mite in apple orchards; powdery mildew, brown rot, aphids, thrips and mites in peach orchards; and, powdery mildew, yellow spider mite and leafhoppers in grapevine orchards. In addition, a methodology called Green Way is presented to provide consistent and crop safety pesticide doses when these are labeled as concentration or ground area doses.

Screening for antibodies against the sheep scab mite (Psoroptes ovis) Pso o 2 antigen in experimentally infested Swifter sheep may fail to identify affected animals

Sheep scab, caused by Psoroptes ovis mites, represents a significant threat to sheep health and welfare. Infestations are diagnosed by parasite identification in skin scrapings, and more recently with a commercial ELISA against serum antibodies to the Pso o 2 mite allergen. However, little is known about the performance of the ELISA in non-UK sheep populations. In this study, six Swifter sheep were experimentally infested with P. ovis. Lesion sizes were monitored and serum IgG against Pso o 2 and the novel Pso-EIP-1 antigens were measured by ELISA. Although all sheep showed signs of infestation, serum from two animals failed to react with Pso o 2. However, they did react to Pso-EIP-1. This indicates that cases of sheep scab in (Swifter) sheep may remain undetected using the Pso o 2 ELISA, which may have implications for routine screening of non- UK sheep breeds.

Sheep, Scab Mites, and Society: The Process and Politics of Veterinary Knowledge in Lesotho, Southern Africa, c. 1900-1933

Abstract This paper reconstructs a sheep-dipping campaign in Lesotho, southern Africa to explore the historical dynamics between local social and political circumstances, ecological change and veterinary knowledge. African livestock owners and the British colonial government accelerated a biological transition from local breeds to non-native merino sheep in the early 1900s to produce wool. Wool-bearing sheep ushered in Psoroptes ovis, a parasitic mite that caused the skin condition called scab. Examining colonial Lesotho's anti-scab campaign from 1903 to 1933, its politics, ideas and procedures, improves our understanding of the past and present interplay between transnational science, farmers, governments and the non-human world. This case study of sheep-dipping and the wool industry that it bolstered shows, too, how people from across the social spectrum interacted within new regulatory communities under a colonial state. These communities, fraught with social cleavages of race and class, and geared towards capitalist production, coalesced during the anti-scab campaigns and formed the political, technical and ideological foundation on which subsequent development schemes were built. Chiefs, stockowners, herders, labourers and European veterinarians too participated in various ways in this process of producing and circulating knowledge, and transforming livestock practices and policies.

Multiple resistance to macrocyclic lactones in the sheep scab mite Psoroptes ovis

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.

Validation of the status of a species with high CO1 and low nuclear genetic divergences: the scab mite Caparinia ictonyctis stat. res. (Acariformes: Psoroptidae) parasitizing the African hedgehog Atelerix albiventris.

We report two host-specific lineages of scab mites of the genus Caparinia, parasitizing European and African hedgehogs. Based on morphology, these mite lineages are closely related sister groups. The morphological differences, however, are subtle and do not provide clear-cut evidence for the existence of separate species. CO1 divergence between these lineages was 7.4-7.8%, well above the CO1 barcoding gaps or thresholds commonly used to separate species, whereas divergence of five nuclear genes was very low, 0.06-0.53%, suggesting that these lineages could belong to a single species with gene flow between them. Thus, there is a conflict between the mitochondrial (CO1) gene and nuclear genes (i.e mito-nuclear discordance). We attribute this conflict to the 'gray zone' where species delimitation is ambiguous due to substantial gene flow. We also report another 'gray zone' species, Psoroptes ovis (a species of veterinary importance), whose within-species CO1 distances reached 6.0%. We provide a detailed morphological description and figures of C. ictonyctis stat. res. from the African hedgehog, using light and SEM microscopy and give morphometric data for this species and its sister species, Caparinia tripilis from Europe. For all known species of Caparinia, we document their host associations and give a key to species of the world based on results of our morphological and molecular analyses and a nearly exhaustive study of museum specimens.

Cox1 barcoding versus multilocus species delimitation: validation of two mite species with contrasting effective population sizes

BackgroundThe cox1-barcoding approach is currently extensively used for high-throughput species delimitation and discovery. However, this method has several limitations, particularly when organisms have large effective population sizes. Paradoxically, most common, abundant, and widely distributed species may be misclassified by this technique.ResultsWe conducted species delimitation analyses for two host-specific lineages of scab mites of the genus Caparinia, having small population sizes. Cox1 divergence between these lineages was high (7.4–7.8%) while that of nuclear genes was low (0.06–0.53%). This system was contrasted with the medically important American house dust mite, Dermatophagoides farinae, a globally distributed species with very large population size. This species has two distinct, sympatric cox1 lineages with 4.2% divergence. We tested several species delimitation algorithms PTP, GMYC, ABGD, BPP, STACEY and PHRAPL, which inferred different species boundaries for these entities. Notably, STACEY recovered the Caparinia lineages as two species and D. farinae as a single species. BPP agreed with these results when the prior on ancestral effective population sizes was set to expected values, although delimitation of Caparinia was still equivocal. No other cox1 species delimitation algorithms inferred D. farinae as a single species, despite the fact that the nuclear CPW2 gene shows some evidence for introgression between the cox1 groups. This indicates that the cox1-barcoding approach may result in excessive species splitting.ConclusionsOur research highlights the importance of using nuclear genes and demographic characteristics to infer species boundaries rather than relying on a single-gene barcoding approach, particularly for putative species having large effective population sizes.

First evidence of resistance to macrocyclic lactones in Psoroptes ovis sheep scab mites in the UK

Ovine psoroptic mange (sheep scab) is an infection of substantial economic and animal welfare concern in the UK. Its prevalence has increased rapidly over the last 20 years and management...

Der f 35: An MD-2-like house dust mite allergen that cross-reacts with Der f 2 and Pso o 2.

Dermatophagoides farinae is a source of airborne house dust mite (HDM) allergens. We elucidated IgE-reactive allergens from D.farinae by two-dimensional immunoblotting-based allergenome analysis, and identified one new allergen, named Der f 35, that possesses IgE-binding capacity comparable to that of Der f 2. The aim of this study was to clarify the allergenic capacity of new HDM allergen Der f 35. We cloned der f 35 from D.farinae mRNA and produced recombinant Der f 35 in Escherichia coli. The IgE-binding capacity of Der f 35 and its cross-reactivity with group 2 allergens from D.farinae and Psoroptes ovis were determined by enzyme-linked immunosorbent assay (ELISA) and ELISA inhibition assays, respectively. The deduced amino acid sequence for der f 35, which possesses the MD-2-related lipid-recognition domain, showed higher identity with group 2 allergens from P.ovis (61.5%) and Blomia tropicalis (50.7%) than with Der f 2 (40.8%). Der f 35 showed IgE-binding frequencies of 77.5% (31/40) for the native form upon allergenome analysis and 51.4% (18/35) for recombinant structure by ELISA. Der f 35 showed cross-reactivity with Der f 2 and Pso o 2 in reaction with HDM-allergic patients' IgE by ELISA inhibition assay. Der f 35 is a candidate major allergen from D.farinae, which is more similar to group 2 allergens from sheep scab mite and storage mites. Der f 35 could be responsible for the cross-reactivity among group 2 mite allergens.

Primary screen for potential sheep scab control agents

The efficacy of potential acaricidal agents were assessed against the sheep scab mite Psoroptes ovis using a series of in vitro assays in modified test arenas designed initially to maintain P. ovis off-host. The mortality effects of 45 control agents, including essential oils, detergents, desiccants, growth regulators, lipid synthesis inhibitors, nerve action/energy metabolism disruptors and ecdysteroids were assessed against adults and nymphs. The most effective candidates were the desiccants (diatomaceous earth, nanoclay and sorex), the growth regulators (buprofezin, hexythiazox and teflubenzuron), the lipid synthesis inhibitors (spirodiclofen, spirotetramat and spiromesifen) and the nerve action and energy metabolism inhibitors (fenpyroximate, spinosad, tolfenpyrad, and chlorantraniliprole).

Ectoparasites of White-Tailed Deer (Artiodactyla: Cervidae) in Southeastern Georgia, USA

Abstract Ectoparasites were collected from 232 freshly culled white-tailed deer, Odocoileus virginianus (Zimmermann), from October through January during 2000–2001, 2001–2002, and 2013–2014 in an 11-county region in southeastern Georgia, USA. Seven species of arthropods were collected: the ticks Amblyomma americanum (L.), Dermacentor albipictus (Packard), and Ixodes scapularis Say (Acari: Ixodidae); the scab mite Psoroptes equi (Hering) (Acari: Psoroptidae); the chewing louse Tricholipeurus lipeuroides (Megnin) (Phthiraptera: Trichodectidae); the sucking louse Solenopotes binipilosus (Fahrenholz) (Phthiraptera: Linognathidae); and the ked Lipoptena mazamae Rondani (Diptera: Hippoboscidae). Prevalence (percentage of deer infested) was significantly higher during the 2013–2014 season for D. albipictus, I. scapularis, and P. equi, and significantly higher during the 2000–2001 season for T. lipeuroides. Prevalence and mean intensity (mean per infested deer) for D. albipictus were both significantly higher on...

Comparative immune responses against Psoroptes ovis in two cattle breeds with different susceptibility to mange.

The sheep scab mite, Psoroptes ovis, is a major problem in the beef cattle industry, especially in Belgian Blue (BB) cattle. This breed is naturally more predisposed to psoroptic mange but reasons for this high susceptibility remain unknown. Different immune responses could be a potential cause; thus in this study, the cutaneous immune response and in vitro cellular immune response after antigen re-stimulation were examined in naturally infested BB. Cytokine production in the skin and in circulating re-stimulated peripheral blood mononuclear cells (PBMC) demonstrated a mixed pro-inflammatory Th2/Th17 profile, with transcription of IL-4, IL-13, IL-6 and IL-17. Strong IL-17 up-regulation in the skin of BB was associated with an influx of eosinophils and other immune cells, potentially leading towards more severe symptoms. Virtually no changes in cutaneous IFN-γ transcription were detected, while there was substantial IFN-γ up-regulation in re-stimulated PBMC from infested and uninfested animals, potentially indicating a role of this pro-inflammatory cytokine in the innate immune response. In Holstein–Friesian (HF) cattle, generally more resistant to P. ovis infection, a largely similar immunologic response was observed. Differences between HF and BB were the lack of cutaneous IL-17 response in infested HF and low transcription levels of IFN-γ and high IL-10 transcription in re-stimulated PBMC from both infested and uninfested animals. Further research is needed to identify potential cell sources and biological functions for these cytokines and to fully unravel the basis of this different breed susceptibility to P. ovis.

Ectoparasites of medical and veterinary importance: drug resistance and the need for alternative control methods.

Despite multiple attempts at eradication, many ectoparasites of humans and domestic livestock remain a persistent problem in the modern world. For many years, a range of pesticide drugs including organophosphates, organochlorides and synthetic pyrethroids provided effective control of these parasites; but intensive use of these drugs has led to the evolution of resistance in many target species. This paper aims to review the effectiveness of current control methods and discuss potential alternatives for the long term sustainable control of ectoparasites. Important medical ectoparasites such as scabies mites, head lice and bed bugs present a significant public health problem, and so adequate control methods are essential. Ectoparasites of domestic livestock and farmed fish (for example sheep scab mites, poultry mites and sea lice) are also of concern given the increasing strain on the world's food supply. These parasites have become resistant to several classes of pesticide, making control very difficult. Recently, an increasing amount of research has focussed on alternative control methods such as insect growth regulators, biological control using essential oils or fungi, as well as vaccine development against some ectoparasites of medical and veterinary importance. Drug resistance is prevalent in all of the ectoparasites discussed in this review. A wide variety of alternative control methods have been identified, however further research is necessary in order for these to be used to successfully control ectoparasitic diseases in the future.

The complete mitochondrial genome of the scab mite Psoroptes cuniculi (Arthropoda: Arachnida) provides insights into Acari phylogeny.

BackgroundLimited 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.MethodsP. cuniculi was collected from a naturally infected New Zealand white rabbit from China and identified by morphological criteria. The complete mt genome of P. cuniculi was amplified by PCR and then sequenced. The relationships of this scab mite with selected members of the Acari were assessed by phylogenetic analysis of concatenated amino acid sequence datasets by Bayesian inference (BI), maximum likelihood (ML) and maximum parsimony (MP).ResultsThis mt genome (14,247 bp) is circular and consists of 37 genes, including 13 genes for proteins, 22 genes for tRNA, 2 genes for rRNA. The gene arrangement in mt genome of P. cuniculi is the same as those of Dermatophagoides farinae (Pyroglyphidae) and Aleuroglyphus ovatus (Acaridae), but distinct from those of Steganacarus magnus (Steganacaridae) and Panonychus citri (Tetranychidae). Phylogenetic analyses using concatenated amino acid sequences of 12 protein-coding genes, with three different computational algorithms (BI, ML and MP), showed the division of subclass Acari into two superorders, supported the monophylies of the both superorders Parasitiformes and Acariformes; and the three orders Ixodida and Mesostigmata and Astigmata, but rejected the monophyly of the order Prostigmata.ConclusionsThe mt genome of P. cuniculi represents the first mt genome of any member of the family Psoroptidae. Analysis of mt genome sequences in the present study has provided new insights into the phylogenetic relationships among several major lineages of Acari species.

Vaccination with recombinant actin from scab mites and evaluation of its protective efficacy against Psoroptes cuniculi infection

The mite Psoroptes cuniculi is globally widespread and has a serious impact on commercial rabbit breeding. Current treatment methods are based on chemotherapy. Because of the disadvantages of these methods, alternative measures are required, and vaccination is one of the most promising strategies. Here, we cloned and expressed the recombinant P. cuniculi actin gene (rPc-act). Antiserum levels against rPc-act in rabbits were used to locate actin distribution in mite sections. Challenge trials were carried out to evaluate the immunity protection of rPc-act in rabbits, with antibody levels determined by ELISA. Sequence analysis of this gene fragment showed 89·26% and 84·91% identity to Sarcoptes scabiei and Mayetiola destructor sequences, respectively. Immunohistochemistry showed rPc-act to locate widely throughout the mites, especially in feet and muscle tissues. Recombinant P. cuniculi actin with QuliA adjuvant was used to immunize six rabbits. Each animal was challenge-infested with 25-50 adult mites. Although IgE levels showed no significant difference to controls, IgG levels were significantly higher, and clinical development showed no significantly different severity of lesions in vaccinated rabbits than in the controls. This study showed that rPc-act is a muscular isotype actin and has no clinical protective efficacy against P. cuniculi.

Clinical efficacy of botanical extracts from Eupatorium adenophorum against the scab mite, Psoroptes cuniculi

This study evaluated the in vivo clinical efficacy of Crofton weed (Eupatorium adenophorum) extracts against the scab mite, Psoroptes cuniculi. A 30-day experiment was performed using New Zealand rabbits that were naturally infested with P. cuniculi on a farm. Rabbits were randomly divided into five groups (6 animals per group); animals in groups A, B and C were treated in each ear topically with 2ml of 1.0, 0.5 and 0.25g/ml (w/v) E. adenophorum ethanol extract, respectively. Animals in groups D and E were treated with ivermectin (by injection; positive controls) and glycerol with water only (by embrocation; negative controls), respectively. Each rabbit was treated twice with separate treatments on days 0 and 7. Rabbits were observed daily and detailed examinations were performed on days 0, 7, 14 and 30, to inspect the presence or absence of mites and scabs/crusts. Clinical infection and the degree of recovery were evaluated, and the rate of reduction in mites and clinical efficacy rate (%) were calculated. The clinical effect of treatment with E. adenophorum extracts was similar to treatment with ivermectin. Seven days after the initial treatment, the mean clinical scores (presence of scabs/crusts) decreased from 3.32, 3.08 and 3.17 to 0.37, 0.47 and 0.48 in the left ears of animals in groups A, B and C, respectively, and from 3.53, 3.73 and 3.67 to 0.40, 0.45 and 0.48 in the right ears of animals in groups A, B and C, respectively, which were similar to the observations recorded in the positive control rabbits. However, the clinical score for negative control rabbits did not decrease significantly (P>0.05) during the experiment, and this changed from 3.32 to 2.75 in the left ears and from 3.50 to 3.25 in the right ears, and there were no significant differences in clinical efficacy between left and right ears. After two treatments (7 days space), the rabbits in groups A, B, C and D had recovered completely 30 days after the last treatment and no recurrences of infection were observed. These results indicate that E. adenophorum contains potent compounds for the effective control of animal acariasis.

Transcriptomic Analysis of Circulating Leukocytes Reveals Novel Aspects of the Host Systemic Inflammatory Response to Sheep Scab Mites

Infestation of ovine skin with the ectoparasitic mite Psoroptes ovis results in the development of a rapid cutaneous inflammatory response, leading to the crusted skin lesions characteristic of sheep scab. To facilitate the identification of novel diagnostic and therapeutic targets, a better understanding of the host-parasite relationship in sheep scab is essential. Although our knowledge of the host's local cutaneous inflammatory response to sheep scab has increased in recent years, we still know relatively little about the mechanisms of this response at the systemic level. This study used a combined network and pathway analysis of the in vivo transcriptomic response of circulating leukocytes to infestation with P. ovis, during a 6 week period. Network graph analysis identified six temporally-associated gene clusters, which separated into two distinct sub-networks within the graph, representing those genes either up or down-regulated during the time course. Functional and pathway analysis of these clusters identified novel insights into the host systemic response to P. ovis infestation, including roles for the complement system, clotting cascade and fibrinolysis. These analyses also highlighted potential mechanisms by which the systemic immune response to sheep scab can influence local tissue responses via enhanced leukocyte activation and extravasation. By analysing the transcriptomic responses of circulating leukocytes in sheep following infestation with P. ovis, this study has provided key insights into the inflammatory response to infestation and has also demonstrated the utility of these cells as a proxy of events occurring at local tissue sites, providing insight into the mechanisms by which a local allergen-induced inflammatory response may be controlled.

Intestinal proteases of free-living and parasitic astigmatid mites

Among arthropod pests, mites are responsible for considerable damage to crops, humans and other animals. However, detailed physiological data on these organisms remain sparse, mainly because of their small size but possibly also because of their extreme diversity. Focusing on intestinal proteases, we draw together information from three distinct mite species that all feed on skin but have separately adapted to a free-living, a strictly ecto-parasitic and a parasitic lifestyle. A wide range of studies involving immunohistology, molecular biology, X-ray crystallography and enzyme biochemistry of mite gut proteases suggests that these creatures have diverged considerably as house dust mites, sheep scab mites and scabies mites. Each species has evolved a particular variation of a presumably ancestral repertoire of digestive enzymes that have become specifically adapted to their individual environmental requirements.