Metabarcoding reveals low prevalence of microsporidian infections in castor bean tick (Ixodes ricinus)

Background Microsporidia is a large group of eukaryotic obligate intracellular spore-forming parasites, of which 17 species can cause microsporidiosis in humans. Most human-infecting microsporidians belong to the genera Enterocytozoon and Encephalitozoon. To date, only five microsporidian species, including Encephalitozoon-like, have been found in hard ticks (Ixodidae) using microscopic methods, but no sequence data are available for them. Furthermore, no widespread screening for microsporidian-infected ticks based on DNA analysis has been carried out to date. Thus, in this study, we applied a recently developed DNA metabarcoding method for efficient microsporidian DNA identification to assess the role of ticks as potential vectors of microsporidian species causing diseases in humans. Methods In total, 1070 (493 juvenile and 577 adult) unfed host-seeking Ixodes ricinus ticks collected at urban parks in the city of Poznan, Poland, and 94 engorged tick females fed on dogs and cats were screened for microsporidian DNA. Microsporidians were detected by PCR amplification and sequencing of the hypervariable V5 region of 18S rRNA gene (18S profiling) using the microsporidian-specific primer set. Tick species were identified morphologically and confirmed by amplification and sequencing of the shortened fragment of cytochrome c oxidase subunit I gene (mini-COI). Results All collected ticks were unambiguously assigned to I. ricinus. Potentially zoonotic Encephalitozoon intestinalis was identified in three fed ticks (3.2%) collected from three different dogs. In eight unfed host-seeking ticks (0.8%), including three males (1.1%), two females (0.7%) and three nymphs (0.7%), the new microsporidian sequence representing a species belonging to the genus Endoreticulatus was identified. Conclusions The lack of zoonotic microsporidians in host-seeking ticks suggests that I. ricinus is not involved in transmission of human-infecting microsporidians. Moreover, a very low occurrence of the other microsporidian species in both fed and host-seeking ticks implies that mechanisms exist to defend ticks against infection with these parasites. Graphical abstract

Borrelia Infections in Ageing Ticks: Relationship with Morphometric Age Ratio in Field-Collected Ixodes ricinus Nymphs

In Europe, Ixodes ricinus plays a major role as a vector of Borrelia burgdorferi sensu lato (s.l.) spirochaetes, the causative agents of Lyme borreliosis, among other pathogens. In unfed ticks, Borrelia spirochaetes experience prolonged nutrient restriction. However, only few studies exist with regard to Borrelia infections in unfed ticks of different physiological ages. Changing body dimensions of unfed ticks, due to the consumption of energy reserves, allow physiological age estimation. The present study investigated the relationship of morphometric age with Borrelia prevalence and spirochaete load in 1882 questing I. ricinus nymphs, collected at two different locations in northern Germany in 2020. In addition, Borrelia species composition was investigated by employing a reverse line blot (RLB) probe panel suitable for the detection of ten different B. burgdorferi s.l. species, as well as the relapsing-fever spirochaete B. miyamotoi. Overall, Borrelia prevalence was 25.8% (485/1882). Whilst there was no statistically significant difference in Borrelia prevalence between the different morphometric age groups, Borrelia infection intensity as determined by probe-based quantitative real-time PCR significantly declined with increasing morphometric age. Borrelia species differentiation by RLB was successful in 29.5% of positive ticks, and revealed B. afzelii as the dominating species (65.0% of the differentiated infections). Additionally, B. garinii, B. valaisiana, B. burgdorferi sensu stricto, B. spielmanii, and B. miyamotoi were detected.

Meteorological and climatic variables predict the phenology of Ixodes ricinus nymphs activity in France, accounting for habitat heterogeneity

Ixodes ricinus ticks (Acari: Ixodidae) are the most important vector for Lyme borreliosis in Europe. As environmental and climate changes might affect the distribution and activity of tick populations, this study aimed to determine the effects of environmental factors, i.e., meteorological, bioclimatic, and habitat characteristics on questing activity of I. ricinus nymphs across diverse climatic types in France over an 8-year period. Questing activity was observed using a repeated removal sampling design with a cloth-dragging technique in 11 sampling sites from 7 tick observatories from 2014 to 2021 at approximately 1-month intervals, involving 631 sampling campaigns. Three phenological patterns were observed, potentially following a climatic gradient. The mixed-effects negative binomial regression revealed that observed nymph counts were driven by different interval-average meteorological variables, including one-month average temperature, previous-season average temperature, and half-year average minimum relative humidity. The interaction effects indicated that the phenology in colder climates peaked differently from that of warmer climates. Also, the land cover characteristics that support the highest baseline abundance were moderate forest fragmentation with transition borders with agricultural areas. Finally, our model could potentially be used to predict seasonal human-tick exposure risks in France that could contribute to mitigating Lyme borreliosis risks.

Transcriptome of the synganglion and characterization of the cys-loop ligand-gated ion channel gene family in the tick Ixodes ricinus.

Ticks represent a major health issue for humans and domesticated animals. Assessing the expression patterns of the tick's central nervous system, known as the synganglion, is an important step in understanding tick physiology and in managing tick-borne diseases. Neuron-specific genes like the cys-loop ligand-gated ion channels (cys-loop LGICs) are important pharmacological targets of acaricides. Here, we carried out the sequencing of transcriptomes of the I. ricinus synganglion, for adult ticks in different conditions (unfed males, unfed females, and partially-fed females). The de novo assembly of these transcriptomes allowed us to obtain a large collection of cys-loop LGICs sequences. A reference meta-transcriptome based on synganglion and whole body transcriptomes was then produced, showing high completeness and allowing differential expression analyses between synganglion and whole body. Many of the genes upregulated in the synganglion were related to biological processes or functions associated with neurotransmission and located in neurones or the synaptic membrane, including most of the cys-loop LGICs. As a first step of a functional study of cysLGICs, we cloned the predicted sequence of the resistance to dieldrin (RDL) subunit homologue, and functionally reconstituted the first GABA-gated receptor of Ixodes ricinus using a hetrologous expression approach. A phylogenetic study was performed for the nicotinic acetylcholine receptors (nAChRs) and for other cys-loop LGICs respectively, showing tick-specific expansions of some types of receptors (Histamine-gated, GluCls).

THE EFFECT OF ACARICIDAL DRUGS BASED ON HERBAL RAW MATERIAL ON THE FERTILITY OF IXODES RICINUS

Therefore, a problem of successful control of ixodes ticks occupies the important place in veterinary medicine and requires searching of new highly effective ascaricidic drugs. Modern synthetic acaricides has led to the environmental pollution problems and further development of resistance within the target tick populations. It really appeared to be the environmental problem. Taking into consideration this fact, the ixodes tick's population decreasing is one of the most important tasks of veterinary science and it requires searching for new environmentally friendly and highly effective acaricides. The aim of our study was to compare the effect of an acaricidal drug developed by us (based on thymol and citral with the addition of sage essential oil) with a synthetic chemical (based on cypermethrin 0.125%) on the fertility of females Ixodes ricinus. Our research showed that the components of the drug can affect the reproductive function of females of ixodes ticks by prolonging the time of egg formation by 3-4 days and reducing their productivity by 80.8% and lead to the death of females before they have completed the process of egg production. The development of environmentally friendly acaricides to limit the number of ectoparasitic arthropods is of practical importance and can give a new understanding of the possible use of essential oils as a part of acaricidal and repellent drugs with low impact on the environment, as well as on human and animal health.

The Isolation of Culturable Bacteria in Ixodes ricinus Ticks of a Belgian Peri-Urban Forest Uncovers Opportunistic Bacteria Potentially Important for Public Health

Most bacteria found in ticks are not pathogenic to humans but coexist as endosymbionts and may have effects on tick fitness and pathogen transmission. In this study, we cultured and isolated 78 bacteria from 954 Ixodes ricinus ticks collected in 7 sites of a Belgian peri-urban forest. Most isolated species were non-pathogenic environmental microorganisms, and were from the Firmicutes (69.23%), Actinobacteria (17.95%) and Proteobacteria (3.84%) phyla. One bacterium isolate was particularly noteworthy, Cedecea davisae, a rare opportunistic bacterium, naturally resistant to various antibiotics. It has never been isolated from ticks before and this isolated strain was resistant to ampicillin, cefoxitin and colistin. Although cultivable bacteria do not represent the complete tick microbiota, the sites presented variable bacterial compositions and diversities. This study is a first attempt to describe the culturable microbiota of ticks collected in Belgium. Further collections and analyses of ticks of different species, from various areas and using other bacterial identification methods would strengthen these results. However, they highlight the importance of ticks as potential sentinel for opportunistic bacteria of public health importance.

A survey for tick (Acari: Ixodidae) infestation on some wild mammals and the first record of Ixodes trianguliceps Birula in Turkey

Ticks (Acari: Ixodidae) are one of the most important ectoparasites of many kinds of terrestrial vertebrates. Between September 2019 and June 2021, we captured a total of 99 wild mammals belonging to 22 species, 14 genera, nine families, and four orders in order to investigate the presence of tick infestations from 14 different locations of 10 provinces in Turkey. Overall, 351 ticks (181 larvae, 156 nymphs, 6 females, and 8 males) were collected from 46 out of 99 wild mammalian species. Ticks were identified as Haemaphysalis erinacei Pavesi (5 males), Haemaphysalis parva Neumann (3 nymphs), Hyalomma marginatum gr. (16 nymphs), Ixodes kaiseri Arthur (1 nymph), Ixodes redikorzevi Olenev (167 larvae, 128 nymphs, and 2 females), Ixodes ricinus (L.) (12 larvae, 1 nymph, and 1 male), Ixodes trianguliceps Birula (2 larvae, and 4 nymphs), and Rhipicephalus turanicus Pomerantzev (3 nymphs, 4 females, and 2 males). Of which, I. trianguliceps was reported in Turkey for the first time. Furthermore, we reported many new tick-host associations for Turkey.

Ticks (Acari: Ixodidae) parasitizing migrating and local breeding birds in Finland

Ticks are globally renowned vectors for numerous zoonoses, and birds have been identified as important hosts for several species of hard ticks (Acari: Ixodidae) and tick-borne pathogens. Many European bird species overwinter in Africa and Western Asia, consequently migrating back to breeding grounds in Europe in the spring. During these spring migrations, birds may transport exotic tick species (and associated pathogens) to areas outside their typical distribution ranges. In Finland, very few studies have been conducted regarding ticks parasitizing migrating or local birds, and existing data are outdated, likely not reflecting the current situation. Consequently, in 2018, we asked volunteer bird ringers to collect ticks from migrating and local birds, to update current knowledge on ticks found parasitizing birds in Finland. In total 430 ticks were collected from 193 birds belonging to 32 species, caught for ringing between 2018 and 2020. Furthermore, four Ixodes uriae were collected from two roosting islets of sea birds in 2016 and 2020. Ticks collected on birds consisted of: Ixodes ricinus (n = 421), Ixodes arboricola (4), Ixodes lividus (2) and Hyalomma marginatum (3). Ixodes ricinus loads (nymphs and larvae) were highest on thrushes (Passeriformes: Turdidae) and European robins (Erithacus rubecula). The only clearly imported exotic tick species was H. marginatum. This study forms the second report of both I. uriae and I. arboricola from Finland, and possibly the northernmost observation of I. arboricola from Europe. The importation of exotic tick species by migrating birds seems a rare occurrence, as over 97% of all ticks collected from birds arriving in Finland during their spring migrations were I. ricinus, a species native to and abundant in Finland.