Description of the male and the larva of Ixodes ariadnae Hornok, 2014

Bat-associated ticks as a potential link for vector-borne pathogen transmission between bats and other animals

BACKGROUND

Potentially zoonotic pathogens have been previously detected in bat-associated ticks, but their role in disease transmission and their frequency of feeding on non-bat hosts is poorly known.

METHODOLOGY/PRINCIPAL FINDINGS

We used molecular blood meal analysis to reveal feeding patterns of the bat-associated tick species Ixodes ariadnae, I. simplex, and I. vespertilionis collected from cave and mine walls in Central and Southeastern Europe. Vertebrate DNA, predominantly from bats, was detected in 43.5% of the samples (70 of 161 ticks) but in these ticks we also detected the DNA of non-chiropteran hosts, such as dog, Canis lupus familiaris, wild boar, Sus scrofa, and horse, Equus caballus, suggesting that bat-associated ticks may exhibit a much broader host range than previously thought, including domestic and wild mammals. Furthermore, we detected the zoonotic bacteria Neoehrlichia mikurensis in bat ticks for the first time, and other bacteria, such as Bartonella and Wolbachia.

CONCLUSIONS/SIGNIFICANCE

In the light of these findings, the role of bat ticks as disease vectors should be urgently re-evaluated in more diverse host systems, as they may contribute to pathogen transmission between bats and non-chiropteran hosts.

A survey of hard ticks associated with cave dwelling mammals in Turkey

Members of the subgenus Eschatocephalus Frauenfeld, 1853 are highly specialized cave-dwelling ectoparasites of bats. We conducted a comprehensive field-based survey on bat ticks in Turkey and provided information about the phylogenetic placement of collected species. Sampling was carried out at 26 caves from 18 provinces around Turkey between 2019 and 2021. Eighty-one tick specimens collected from the cave environment or on various cave roosting bats resulted in five species: Ixodes vespertilionis, Ixodes simplex, Ixodes ariadnae, Ixodes kaiseri, and Haemaphysalis erinacei. While I. simplex was the most frequently collected species with a rate of 56.2% mainly from bats (Miniopterus schreibersii), I. vespertilionis was the most prevalent species (65.4%) and found mainly on cave walls. The first record of I. ariadnae was provided for Turkey. Phylogenetic trees were built using mt 16S rDNA and COI markers. Our results demonstrated the presence of two distinct lineages of I. vespertilionis in Turkey; one lineage grouped with European isolates, whereas three sequences clustered separately. The phylogenetic pattern of I. simplex was consistent with previous results; this clade was clustered distantly to other bat tick species. The significance of the surprising records of H. erinacei and I. kaiseri in caves is also discussed.

Bats and ticks: host selection and seasonality of bat-specialist ticks in eastern Europe

Background

Parasites may actively seek for hosts and may use a number of adaptive strategies to promote their reproductive success and host colonization. These strategies will necessarily influence their host specificity and seasonality. Ticks are important ectoparasites of vertebrates, which (in addition to directly affecting their hosts) may transmit a number of pathogens. In Europe, three hard tick species (Ixodidae: Ixodes ariadnae, I. simplex and I. vespertilionis) and at least two soft tick species (Argasidae: Argas transgariepinus and A. vespertilionis) are specialized for bats.

Methods

Here we report data on the host range of these ticks and the seasonality of tick infestation on wild caught bats in south-east Europe. We collected 1803 ticks from 30 species of bats living in underground shelters (caves and mines) from Romania and Bulgaria. On the basis of tick–host associations, we tested several hypotheses on host–parasite evolutionary adaptations regulating host specificity, seasonality and sympatric speciation.

Results

We observed significant differences in host specificity and seasonality of abundance between the morphologically different bat specialist ticks (I. simplex and I. vespertilionis) likely caused by their host choice and their respective host-seeking behavior. The two highly generalist, but morphologically similar tick species (I. ariadnae and I. vespertilionis) showed temporal differences in occurrence and activity, thus exploiting significantly different host communities while occurring in geographical sympatry.

Conclusions

We conclude that bat-specialist ticks show a wide range of adaptations to their hosts, with differences in specificity, seasonality of occurrence, the prevalence and intensity of infestation and all these contribute to a successful division of temporal niches of ticks sharing morphologically similar hosts occurring in geographical sympatry.

Diversity of Borrelia burgdorferi sensu lato species in Ixodes ticks (Acari: Ixodidae) associated with cave-dwelling bats from Poland and Romania

Bats comprise one quarter of the world's mammal species. In Europe, three nidicolous Ixodes tick species, I. vespertilionis, I. simplex and I. ariadnae are specifically associated with cave-dwelling bats, but their role as potential vectors of zoonotic agents is unknown. In this study, we used PCR-based methods to provide the first evidence of Borrelia burgdorferi sensu lato (s.l.) infections in the three bat-associated tick species collected from ten bat species sampled in Poland and Romania. B. burgdorferi s.l. was detected in 24% (64/266) of tick samples, and 40.3% (60/149) of the bats carried infected chiropterophilic ticks. In Poland, the B. burgdorferi s.l. infection prevelance of I. ariadnae ticks parasitizing Myotis species was four times higher compared to the I. vespertilionis ticks derived from Rhinolophus hipposideros bats (44.4% vs.10%, respectively). The observed differences in infection prevalence could be explained by differences in reservoir potential between bat species. Bats from the genus Myotis and Miniopterus schreibersii carried more infected ticks than R. hipposideros regardless of the tick species. Analysis of the flaB gene sequences revealed seven species from the B. burgdorferi s.l. complex (B. afzelii, B. carolinensis, B. garinii, B. lanei, B. spielmanii, B. burgdorferi s.s., and B. valaisiana), of which five are considered as human pathogens. This large diversity of Borrelia species may reflect differences in susceptibility of chiropteran hosts and/or the tick vectors. Generally, mammal-associated B. burgdorferi s.l. species were more common than bird-associated species. Our study provides evidence for new enzootic transmission cycles of B. burgdorferi s.l. spirochetes involving nidicolous Ixodes tick species and cave-dwelling bats.

Description of the male and the larva of Ixodes collaris Hornok, 2016 with drawings of all stages

Background

Ixodes collaris Hornok, 2016 is a recently discovered tick species associated with bats in Asia. This study provides the description of the male and the larva, as well as high quality drawings of all stages.

Methods

Ticks were collected from cave walls and bats in Phia Oac (Vietnam). DNA was extracted from one individual of each stage/sex, while another was morphometrically analysed. Based on two genetic markers, all ticks were identified as I. collaris.

Results

The male of I. collaris has long legs (i.e. the length of Haller’s organ exceeds the maximum diameter of tarsus I), unlike the male of I. simplex Neumann, 1906, but similarly to males of I. vespertilionis Koch, 1844 and I. ariadnae Hornok, 2014. The lateral and medial edges of the palpi of male I. collaris are both convexly curved, unlike in I. ariadnae and I. simplex, but similarly to I. vespertilionis. The male of I. collaris has long palpal setae (up to 210 µm), unlike the males of I. ariadnae (30–100 µm) and I. simplex (20–80 µm), but similarly to I. vespertilionis (100–200 µm). Males of I. collaris have sparse distribution of long palpal setae (vs dense in I. vespertilionis) and posteriorly diverging, sclerotized trapezoid ridge dorsally on the basis capituli (posteriorly convergent, U-shaped and less evident in I. vespertilionis). The larva of I. collaris has long legs (unlike the larva of I. simplex, but similarly to I. vespertilionis and I. ariadnae), elongated club-shaped palpi (240 × 70 vs 200 × 90 µm in I. ariadnae, 200 × 70 µm in I. vespertilionis; and 140 × 60 µm in I. simplex:), pentagonal scutum, which is longer than broad (different from I. ariadnae and I. simplex, but similar to that of I. vespertilionis). The larva of I. collaris has strongly concave caudolateral margin of ventral basis with perpendicular angle (vs slightly concave, with obtuse angle in I. vespertilionis) and a prominent, dark sclerotized edge, “collar” (absent in I. vespertilionis).

Conclusion

Several features allow to distinguish the male and the larva of I. collaris morphologically from those of other bat-associated ixodid tick species.

Illustrated redescription of the male of Ixodes simplex Neumann, 1906

Ixodes simplex is a tick species of bats, mainly reported from Schreibers' Bent-winged bat, Miniopterus schreibersii, all over its host's range. While being a common parasite of cave-dwelling bat species, the initial description of males is poor (based on a sole damaged specimen), lacking distinctive features. This study describes the male of I. simplex also providing measurements for a number of characters, using a series 10 of specimens. Males of I. simplex show the following characteristics distinct from males of I. ariadnae and I. vespertilionis: idiosoma is shorter (2.6 mm vs. 3.4-4.7 mm); the palps of I. simplex males are laterally curved (bent) (while straight in I. ariadnae and gradually curving in I. vespertilionis), the genital opening is anterior in position between coxae II (whereas posterior to second intercoxal space in I. vespertilionis); coxae II are to some extent rectangular (vs. rounded in I. ariadnae); coxae IV have a prominent tuft of long hairs (missing in the other two species). Most importantly, the legs of I. simplex males are considerably shorter than in males of the other two species (2.7-3.3 mm vs. 7-10 mm). The description is completed with high-quality pictures highlighting all the mentioned features.