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Abstract Background The family Capillariidae is a group of thread-like nematodes of 27 genera and over 300 species that infect a great variety of hosts including humans. Among these, some taxa such as the genus Aonchotheca have remained controversial regarding their systematic status for decades. The aim of the current study was to verify Aonchotheca’s systemic status and to further determine whether it is a distinct genus from Capillaria using molecular and phylogenetic analyses. Results We sequenced the mitochondrial (mt) genome and nuclear small subunit (18S) rRNA gene of Aonchotheca putorii, a representative species of the genus, and investigated its systematic status in Trichinellida using maximum likelihood and Bayesian inference. The differences in amino acid sequences of 13 protein-coding genes were 12.69–67.35% among Aonchotheca, Capillaria, Eucoleus, and Pseudocapillaria with cox1 (12.69%) and atp8 (67.35%) as the most and the least conserved gene, respectively, and the difference of two mt rRNAs was 18.61–34.15%. Phylogenetic analyses of the complete mt genome and 18S rRNAs unequivocally showed that Aonchotheca was a distinct genus from Capillaria. Conclusions Large difference exists among Aonchotheca, Capillaria, Eucoleus, and Pseudocapillarias. Aonchotheca putorii is the first species in the genus Aonchotheca for which a complete mitogenome has been sequenced. These data are useful for phylogenetics, systematics and the evolution of Capillariidae. Graphical Abstract

Parasites have the potential to negatively affect host populations, if infection intensity is high. For parasites in which part of life cycle takes place outside the host, host infection intensity is likely affected by climate condition. Therefore, the parasite's impact on the host populations could be related to climatic conditions and may be altered with climate change. The aim of our study was to analyse the prevalence and infection intensity of two nematodes (Aonchotheca putorii and Molineus patens) from the Northern Hemisphere in relation to variations in climatic conditions. We reviewed 54 published studies on the occurrence of these two nematode species in 7 mustelid hosts. For A. putorii, infection parameters were higher when the stomach was included in the analyses compared to M. patens. The seasonality of precipitation influenced the prevalence the most, and the mean temperature of the warmest quarter had the strongest influence on infection intensity. The predicted prevalence of M. patens increased with increasing seasonal variation in precipitation, while the prevalence of A. putorii decreased. The predicted infection intensity of M. patens decreased with increasing precipitation seasonality, whereas the intensity of A. putorii infection did not change much. A. putorii infection intensity significantly decreased with increasing mean temperature of the warmest quarter, while the infection intensity of M. patens was not significantly related to this variable. Prevalence and infection intensity varied over the geographic range for both parasites, broadly with higher levels in northern latitudes for A. putorii and in southern latitudes for M. patens. Our study highlights the differences between these two nematode species and shows that the severity of host infection by these parasites is complex and mediated by climatic conditions. The results suggest that current climate change may potentially modify susceptibility and exposure to parasitic infections in mustelids.

Background: The family Capillariidae is a group of thread-like nematodes of 27 genera and over 300 species that infect a great variety of hosts including humans. Among these, some taxa such as the genus Aonchotheca have remained controversial regarding their systematic status for decades. The aim of the current study was to verify Aonchotheca's systemic status and to further determine whether it is a distinct genus from Capillaria using molecular and phylogenetic analyses. Results: We sequenced the mitochondrial (mt) genome and nuclear small subunit (18S) rRNA gene of Aonchotheca putorii, a representative species of the genus, and investigated its systematic status in Trichinellida using maximum likelihood and Bayesian inference. The differences in amino acid sequences of 13 protein-coding genes were 12.69–67.35% among Aonchotheca, Capillaria, Eucoleus, and Pseudocapillaria with cox1 (12.69%) and atp8 (67.35%) as the most and the least conserved gene, respectively, and the difference of two mt rRNAs was 18.61–34.15%. Phylogenetic analyses of the complete mt genome and 18S rRNAs unequivocally showed that Aonchotheca was a distinct genus from Capillaria. Conclusions: Large difference exists among Aonchotheca, Capillaria, Eucoleus, and Pseudocapillarias. Aonchotheca putorii is the first species in the genus Aonchotheca for which a complete mitogenome has been sequenced. These data are useful for phylogenetics, systematics and the evolution of Capillariidae. [ABSTRACT FROM AUTHOR]

Parasites may negatively affect hosts condition, especially when infection intensity is high. Species introduced to a new habitat are often less exposed to a parasite pressure but may accumulate parasites in time. American mink (Neovison vison) introduced to Europe, Asia, and South America is an example of such invasive species. We analysed nematode prevalence and digestive tract infection intensity in 796 feral American mink from Poland. The analyses were performed separately for stomach, duodenum, small intestine and large intestine. Parasite species identification was performed using molecular methods based on highly conserved nuclear 18S rRNA gene and supplemented with morphological analysis. In total, we collected 26,852 nematodes and 98.6% of them were isolated from mink stomachs. We found positive association between infection intensity in stomach and other parts of digestive tract. Nematode prevalence was estimated at 63.8% and average infection intensity per one American mink at 52.9 (range from 1 to 1118). If the stomach results were theoretically and intentionally omitted the prevalence was 5 times lower (12.7%) and infection intensity 14 times lower (3.7; range 1–50). We identified two nematode species in digestive tracts of American mink: Aonchotheca putorii and Molineus patens. The 18S rRNA gene sequence of Molineus patens has been reported for the first time. The results showed that Aonchotheca putorii is a dominating nematode in the invasive American mink and that it inhabits stomach intensively and preferably.

Parasites have the potential to negatively affect host populations, if infection intensity is high. For parasites in which part of life cycle takes place outside the host, host infection intensity is likely affected by climate condition. Therefore, the parasite's impact on the host populations could be related to climatic conditions and may be altered with climate change. The aim of our study was to analyse the prevalence and infection intensity of two nematodes (Aonchotheca putorii and Molineus patens) from the Northern Hemisphere in relation to variations in climatic conditions. We reviewed 54 published studies on the occurrence of these two nematode species in 7 mustelid hosts. For A. putorii , infection parameters were higher when the stomach was included in the analyses compared to M. patens. The seasonality of precipitation influenced the prevalence the most, and the mean temperature of the warmest quarter had the strongest influence on infection intensity. The predicted prevalence of M. patens increased with increasing seasonal variation in precipitation, while the prevalence of A. putorii decreased. The predicted infection intensity of M. patens decreased with increasing precipitation seasonality, whereas the intensity of A. putorii infection did not change much. A. putorii infection intensity significantly decreased with increasing mean temperature of the warmest quarter, while the infection intensity of M. patens was not significantly related to this variable. Prevalence and infection intensity varied over the geographic range for both parasites, broadly with higher levels in northern latitudes for A. putorii and in southern latitudes for M. patens. Our study highlights the differences between these two nematode species and shows that the severity of host infection by these parasites is complex and mediated by climatic conditions. The results suggest that current climate change may potentially modify susceptibility and exposure to parasitic infections in mustelids. [Display omitted] • Analyses of the infection intensity of two nematodes on seven mustelid species on a large geographical scale. • Climate modulates the infection parameters of the studied nematodes. • Climatic conditions have contrasting effects on the two nematode species. • The different effect of climate on parasite infection intensity is related to differences in their life cycles. • Climate change may modify parasite infections and parasite impacts on wild carnivores. [ABSTRACT FROM AUTHOR]

Parasites may negatively affect hosts condition, especially when infection intensity is high. Species introduced to a new habitat are often less exposed to a parasite pressure but may accumulate parasites in time. American mink (Neovison vison) introduced to Europe, Asia, and South America is an example of such invasive species. We analysed nematode prevalence and digestive tract infection intensity in 796 feral American mink from Poland. The analyses were performed separately for stomach, duodenum, small intestine and large intestine. Parasite species identification was performed using molecular methods based on highly conserved nuclear 18S rRNA gene and supplemented with morphological analysis. In total, we collected 26,852 nematodes and 98.6% of them were isolated from mink stomachs. We found positive association between infection intensity in stomach and other parts of digestive tract. Nematode prevalence was estimated at 63.8% and average infection intensity per one American mink at 52.9 (range from 1 to 1118). If the stomach results were theoretically and intentionally omitted the prevalence was 5 times lower (12.7%) and infection intensity 14 times lower (3.7; range 1–50). We identified two nematode species in digestive tracts of American mink: Aonchotheca putorii and Molineus patens. The 18S rRNA gene sequence of Molineus patens has been reported for the first time. The results showed that Aonchotheca putorii is a dominating nematode in the invasive American mink and that it inhabits stomach intensively and preferably. [Display omitted] • Parasitic infection monitoring in the wild is the important indicator of the population condition. • Aonchotheca putorii is a dominating nematode in the invasive American mink. • Aonchotheca putorii inhabits mink stomach intensively and preferably. • Molecular identification of Molineus patens has been reported for the first time. • The importance of using of the whole digestive tract in parasitological monitoring has been emphasized. [ABSTRACT FROM AUTHOR]

A male badger (Meles meles) died in a traffic accident admitted to the Parasitology Lab of the Faculty of Veterinary Medicine of Ondokuz Mayıs University was examined systemically. Parasitological examination revealed that the badger was infected with 3 ectoparasites and 3 endoparasites. Following ectoparasites were detected; one flea (Paraceras melis) and two ticks (Ixodes ricinus, Rhipicephalus sanguineus) and as endoparasites one cestode (Mesocestoides melesi) and two nematode species (Aonchotheca putorii, Molineus patens). Badger is a new host for all parasites in Turkey, while M. melesi is the first report for the helminth fauna of Turkey. [ABSTRACT FROM AUTHOR]

Parasites may negatively affect hosts condition, especially when infection intensity is high. Species introduced to a new habitat are often less exposed to a parasite pressure but may accumulate parasites in time. American mink ( Neovison vison ) introduced to Europe, Asia, and South America is an example of such invasive species. We analysed nematode prevalence and digestive tract infection intensity in 796 feral American mink from Poland. The analyses were performed separately for stomach, duodenum, small intestine and large intestine. Parasite species identification was performed using molecular methods based on highly conserved nuclear 18S rRNA gene and supplemented with morphological analysis. In total, we collected 26,852 nematodes and 98.6% of them were isolated from mink stomachs. We found positive association between infection intensity in stomach and other parts of digestive tract. Nematode prevalence was estimated at 63.8% and average infection intensity per one American mink at 52.9 (range from 1 to 1118). If the stomach results were theoretically and intentionally omitted the prevalence was 5 times lower (12.7%) and infection intensity 14 times lower (3.7; range 1-50). We identified two nematode species in digestive tracts of American mink: Aonchotheca putorii and Molineus patens . The 18S rRNA gene sequence of Molineus patens has been reported for the first time. The results showed that Aonchotheca putorii is a dominating nematode in the invasive American mink and that it inhabits stomach intensively and preferably., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2020 The Author(s).)