Chorioptes mites: re-evaluation of species integrity

Morphological diagnosis and successful treatment of chorioptic mange in 2 South American coatis (Nasua nasua)

Two female South American coatis (Nasua nasua) kept in a zoo in Southern Germany presented with pruritus and moderate hair loss at the dorsal trunk, thigh areas and alongside the tail. Otherwise the animals showed no clinical signs. While the clinical general examination as well as cytology of dermatologic samples showed no pathologic changes, Chorioptes sp. mites could be identified in a superficial skin scraping. Two consecutive topical applications of a selamectin/sarolaner spot-on formulation 4 weeks apart lead to a complete resolution. No side effects were observed.

Chorioptic Mange in an American Black Bear (Ursus americanus) from Massachusetts, USA

American black bears (Ursus americanus) are increasingly reported to develop mange. This report describes a case of mange associated with a Chorioptes species, which has not previously been reported, to our knowledge, in free-ranging black bears. Basic clinical findings as well as methods of identification for this mite are provided.

Transcriptome-based analysis of putative allergens of Chorioptes texanus

Background

Mites of the genus Chorioptes are non-burrowing and cause mange in a wide range of domestic and wild animals including cattle, horses, sheep, goats, panda, moose, camelids, mydaus and alpacas. Molecular biology and host-parasite interactions of Chorioptes texanus are poorly understood, and only a few C. texanus genes and transcript sequences are available in public databases including the allergen genes.

Methods

Chorioptes texanus RNA was isolated from mites, and the transcriptome of C. texanus was analyzed using bioinformatics tools. Chorioptes texanus unigenes were compared with the allergen protein sequences from the mite allergen database website to predict the potential allergens. Chorioptes texanus putative allergen unigenes were compared with hydrolase genes by building a C. texanus hydrolase gene library with the best match of the homologous sequences. Three allergen genes were cloned and expressed, their recombinant proteins were purified and their allergenic activities were preliminarily investigated.

Results

Transcriptome sequencing (RNA-Seq) of C. texanus was analyzed and results demonstrated that 33,138 unigenes were assembled with an average length of 751 bp. A total of 15,130 unigenes were annotated and 5598 unigenes were enriched in 262 KEGG signaling pathways. We obtained 209 putative allergen genes and 34 putative allergen-hydrolase genes. Three recombinant allergen proteins were observed to induce different degrees of allergic reactions on rabbit skin.

Conclusions

The present transcriptome data provide a useful basis for understanding the host-parasite interaction and molecular biology of the C. texanus mite. The allergenic activities of recombinant Euroglyphus maynei 1-like (Eur m 1-like) protein, Dermatophagoides ptreronyssinus 1-like (Der p 1-like) protein and Dermatophagoides ptreronyssinus 7-like (Der p 7-like) protein were preliminarily investigated by intradermal skin test. Meanwhile, differences in eosinophil counts were observed in different injected sites of the skin. The identification of putative allergen genes and hydrolase genes offers opportunities for the development of new diagnostic, prevention and treatment methods.

Integrated Bayesian species delimitation and morphological diagnostics of chorioptic mange mites (Acariformes: Psoroptidae: Chorioptes)

The external morphology of adult and immature stages of mange mites of the genus Chorioptes was investigated with the aid of light and scanning electron microscopy. A molecular phylogeny of this genus was inferred based on six genes (18S, 28S rDNA, EF1-α, SRP54, HSP70, and CO1). The validity of four species (Ch. bovis, Ch. panda, Ch. texanus, and Ch. sweatmani sp. nov. described from the moose from Sweden, Finland, and Russia) was confirmed based on morphology and a Bayesian species delimitation analysis incorporating both gene tree uncertainties and incomplete lineage sorting via the coalescent process model in BPP. Sequence data for Ch. crewei and Ch. mydaus was not available but their morphology strongly suggests their validity. The six valid Chorioptes species are diagnosed using type and non-type specimens, and a key to species is provided. Ch. sweatmani differs from closely related Ch. texanus by the following features: in males, the body length, including the gnathosoma, is 380-405 μm (vs. 220-295 in Ch. texanus), the idiosoma is 3-4 times longer than setae cp (vs. 1.3-1.6 times longer), legs III are approximately three times longer than setae sRIII (vs. 1.8-2 times longer), the apical spur of tarsus III is curved (vs. straight), a spur near seta fIII base is not developed (vs. small but distinct); in females, setae h2 are 1.4-1.5 times shorter than legs IV (vs. about two times longer). Hosts and distribution records of Chorioptes species are summarized.

Acaricidal activity of petroleum ether extracts from Eupatorium adenophorum against the ectoparasitic cattle mite, Chorioptes texanus

In this study, we evaluated the acaricidal efficacy of extracts obtained from the plant Eupatorium adenophorum against the common cattle mite Chorioptes texanus. The results showed that 95% ethanol extracts at concentrations of 1.0, 0.5, and 0.25 g/mL (w/v) were highly toxic to C. texanus in vitro, killing 100% of mites in 4 h. Similarly, petroleum ether extracts of E. adenophorum resulted in between 80 and 100% mortality of mites in vitro at concentrations of 0.1, 0.05, and 0.025 mL/mL (v/v) within 4 h. In clinical trials, all infected individuals completely recovered after two treatments administered at 7-day intervals and remained disease-free at 60 days posttreatment. The clinical effect of treatment with E. adenophorum petroleum ether extracts was similar to that of treatment with the acaricide fenvalerate. These results indicated that E. adenophorum contains novel potential acaricidal compounds that can effectively control mites in livestock.