Tick Eggs Research Articles

Haemaphysalis longicornis calreticulin is not an effective molecular tool for tick bite diagnosis and disruption of tick infestations

BackgroundTick calreticulin (CRT) is a calcium-binding protein secreted into the host during blood feeding. It has been used as a biomarker of tick exposure and has potential as an anti-tick vaccine, but there is no information about these uses for Haemaphysalis longicornis CRT (HlCRT). We synthesized recombinant H. longicornis CRT (rHlCRT) and evaluated its potential for tick bite diagnosis and for disrupting tick infestations. MethodsThe responses of mice and rabbits exposed to H. longicornis ticks were measured with ELISA to determine the antibody level against rHlCRT. To evaluate the effects of rHlCRT-induced anti-tick immunity, engorgement weight, tick engorgement index (TEI), feeding duration, ecdysis rate, and egg weight per engorged tick were compared between ticks fed on immunized and normal mice. ResultsMean anti-tick CRT antibody levels in sera collected from mice at 1 and 15 days after primary tick exposure were not significantly different from the mean antibody levels in negative control mice that were not bitten by ticks (all P values > 0.05). No significant anti-HlCRT IgG responses developed in mice after second exposure to tick bites compared with the level of anti-HlCRT antibody response in negative control mice (all P values > 0.25). For rabbits, no significant differences in the antibody levels were observed in animals before challenge infestation and after tick exposures, and in animals after two tick exposures (all P values > 0.10). There were no significant differences in the body weight of ticks fed on immunized and normal mice (all P values > 0.15). No significant differences in TEI were observed between ticks fed on immunized mice and normal control mice (all P values > 0.50). There were no significant differences in feeding duration for female ticks, and feeding duration and ecdysis rate for nymphs in the experimental and control groups (all P values > 0.10 for feeding duration and P value = 0.19 for ecdysis rate). We did not observe a significant difference in egg weight per tick in the rHlCRT-immunized and the control groups (P = 0.88). ConclusionsHlCRT in H. longicornis tick saliva proteins appears to be nonimmunogenic to mammalian hosts like mice and rabbits. Vaccination with rHlCRT did not generate effective immunity against parthenogenetic and bisexual H. longicornis nymphs or female ticks. These results indicate that HlCRT is not a suitable molecular candidate for H. longicornis tick bite diagnosis and not effective for the disruption of tick infestations.

Acaricidal Potential and Ecotoxicity of Metallic Nano-Pesticides Used against the Major Life Stages of Hyalomma Ticks.

Ticks (Acari: Ixodidae) are blood-feeding parasites capable of transmitting diseases to animals (Piroplasmosis) and humans (Congo fever, Lyme disease). The non-judicious use of chemical acaricides has led to the development of acaricide-resistant ticks, making the control of ticks and tick-borne diseases difficult. This study reports the efficacy of magnesium oxide (MgO), iron oxide (Fe2O3), and zinc oxide (ZnO) nanoparticles (NPs) as alternatives to traditional acaricides/pesticides using in vitro tests against major representative stages of Hyalomma ticks. Nanopesticides were chemically synthesized as rods (Fe2O3), stars (ZnO), and spheres (MgO) and were characterized by XRD and SEM analysis. The in vitro bioassays included adult immersion, larval immersion, and larval packet tests. Non-target effects of the nanopesticides were evaluated using snails. The LC90 values of Fe2O3 NPs (4.21, 2.83, 0.89 mg/L) were lowest followed by MgO (4.27, 2.91, 0.93 mg/L) and ZnO (4.49, 3.05, 0.69 mg/L), for the tick adult, larval and egg stages, respectively. Fe2O3 NPs were capable of arresting oviposition and larval hatching in the study ticks in vitro. The snail toxicity experiments revealed minimum to mild off-target effects for all nanopesticides tested. This study is the first to report the comparative efficacy of magnesium, iron, and zinc nanomaterials for toxicity in egg, adult and larval stages of Hyalomma ticks. Further studies of NPs on establishing the efficacy against ticks and safety at host-human-environment interface could lead to promising nanopesticde applications.

Bacterial microbiota analysis demonstrates that ticks can acquire bacteria from habitat and host blood meal.

Ticks have a diversity of habitats and host blood meals. Whether and how factors such as tick developmental stages, habitats and host blood meals affect tick bacterial microbiota is poorly elucidated. In the present study, we investigated the bacterial microbiotas of the hard tick Haemaphysalis longicornis, their blood meals and habitats using 16S rRNA gene high-throughput sequencing. The bacterial richness and diversity in ticks varied depending on the tick developmental stage and feeding status. Results showed that fed ticks present a higher bacterial richness suggesting that ticks may acquire bacteria from blood meals. The significant overlap of the bacteria of fed ticks and the host blood also supports this possibility. Another possibility is that blood meals can stimulate the proliferation of certain bacteria. However, most shared bacteria cannot transmit throughout the tick life cycle, as they were not present in tick eggs. The most shared bacteria between ticks and habitats are members of the genera Staphylococcus, Pseudomonas, Enterobacter, Acinetobacter and Stenotrophomonas, suggesting that these environmental bacteria cannot be completely washed away and can be acquired by ticks. The predominant proportion of Coxiella in fed females further demonstrates that this genus is involved in H. longicornis physiology, such as feeding activity and nutritional provision. These findings further reveal that the bacterial composition of ticks is influenced by a variety of factors and will help in subsequent studies of the function of these bacteria.

Значение исследований иксодовых клещей в эпизоотологии кровепаразитарных болезней

The article clarifies the species composition of pathogens of blood parasitic diseases in cattle in various regions of Azerbaijan. As a result of studies of peripheral blood smears of cattle, organs and eggs of ixodid ticks, we have established the spread of four types of pathogens of blood parasitic diseases: Piroplasma bigeminum, Babesia (Francaiella) colchica, Theileria annulata and Anaplasma marginale. Microscopic examination of the salivary glands, ovaries, intestines and malpighian vessels, as well as the eggs of the Hyalomma anatolicum, H. plumbeum, Boophilus calcaratus, Ixodes ricinus and Rhipicephalus sanguineus ticks collected from sick and clinically healthy animals, in addition to the parasites detected in the blood, additionally revealed other types of parasites. Thus, Babesia caucasica was found in Ixodes ricinus ticks, Theileria mutans in Hyalomma anatolicum; in ticks Rhipicephalus sanguineus — the causative agent of piroplasmosis in dogs Piroplasma canis. Of great practical and scientific interest is the identification of the parasite in the eggs and organs of the tick Boophilus calcaratus. This species of parasite is not described in the world catalog of piroplasmids and differs sharply from piroplasmas and babesias, which are carried by Boophilus calcaratus, in terms of morphological features and intensity of invasion. We designated this parasite in the article as Babesia sp.

Activity of terpenes derived from essential oils against Sarcoptes scabiei eggs

BackgroundThe limited ovicidal activity of currently available acaricides is a significant obstacle to efficacious scabies treatment. Several essential oils or their respective components have proved to be active against the eggs of arthropods, mainly lice and ticks. Information on the activity of these oils and/or components against the eggs of mites remains very limited. The aim of this study was to assess the activity of six terpenes (carvacrol, eugenol, geraniol, citral, terpinen-4-ol and linalool) commonly found in essential oils against the eggs of Sarcoptes scabiei.MethodsSarcoptes eggs were exposed to paraffin oil containing 1, 2.5, or 5% of each terpene tested. After a 12-h exposure period, the eggs were washed and placed in paraffin oil for hatching. Embryonic development following treatment was assessed every day to determine the stage of developmental arrest.ResultsThe median effective concentration to obtain 50% egg mortality (EC50) was 0.5, 0.9, 2.0, 4.8, 5.1 and 9.8% for carvacrol, eugenol, geraniol, citral, terpinen-4-ol and linalool, respectively. The microscopic images of eggs after each treatment indicated that these six terpenes may act by penetrating through the aeropyles on the egg surface.ConclusionsIn conclusion, carvacrol, eugenol and geraniol possess significant ovicidal activities, which should be considered as promising ovicidal agents for the treatment of scabies.Graphical

Winter Tick Burdens for Moose Are Positively Associated With Warmer Summers and Higher Predation Rates

Climate change is expected to modify host-parasite interactions which is concerning because parasites are involved in most food-web links, and parasites have important influences on the structure, productivity and stability of communities and ecosystems. However, the impact of climate change on host–parasite interactions and any cascading effects on other ecosystem processes has received relatively little empirical attention. We assessed host-parasite dynamics for moose (Alces alces) and winter ticks (Dermacentor albipictus) in Isle Royale National Park over a 19-year period. Specifically, we monitored annual tick burdens for moose (estimated from hair loss) and assessed how it covaried with several aspects of seasonal climate, and non-climatic factors, such as moose density, predation on hosts by wolves (Canis lupus) and wolf abundance. Summer temperatures explained half the interannual variance in tick burden with tick burden being greater following hotter summers, presumably because warmer temperatures accelerate the development of tick eggs and increase egg survival. That finding is consistent with the general expectation that warmer temperatures may promote higher parasite burdens. However, summer temperatures are warming less rapidly than other seasons across most regions of North America. Therefore, tick burdens seem to be primarily associated with an aspect of climate that is currently exhibiting a lower rate of change. Tick burdens were also positively correlated with predation rate, which could be due to moose exhibiting risk-sensitive habitat selection (in years when predation risk is high) in such a manner as to increases the encounter rate with questing tick larvae in autumn. However, that positive correlation could also arise if high parasite burdens make moose more vulnerable to predators or because of some other density-dependent process (given that predation rate and moose density are highly correlated). Overall, these results provide valuable insights about interrelationships among climate, parasites, host/prey, and predators.

Protective efficacy of the peptide Subolesin antigen against the cattle tick Rhipicephalus microplus under natural infestation

The cattle tick Rhipicephalus microplus affect animal health, welfare, and cattle production in tropical and subtropical zones of the world. Anti-tick vaccines have been an effective alternative for cattle tick control instead of traditional chemical products. To date, Subolesin antigen has shown efficacy for the control of tick infestation in cattle, and previous studies showed that one peptide derived from this protein has demonstrated to elicit a strong and specific humoral immune response. Based on these findings, herein we characterized the efficacy of the peptide Subolesin for the control of cattle tick, R. microplus infestation under field conditions. Twenty-four female calves were assigned to four experimental groups and immunized with three subcutaneous doses of the peptide Subolesin, Bm86, both antigens (dual vaccine) and adjuvant/saline alone, respectively. Serum antibody levels (IgG) were assessed by ELISA and confirmed by Western blot; also, reproductive performance of naturally infested R. microplus was determined. The results showed that immunizations with the experimental antigens reduced tick infestations with vaccine’s efficacy of 67 % (peptide Subolesin), 56 % (Bm86), and 49 % (dual vaccine) based on adult tick numbers, oviposition, and egg fertility between vaccinated and control animals. Peptide Subolesin-immunized calves developed a strong humoral immune response expressed by high anti-pSubolesin IgG levels, and the Western blot analysis confirmed that it is immunogenic. Cattle receiving Bm86 and dual vaccine showed less protection, although Bm86 was within the range reported previously. The negative correlation between antibody levels and reduction of naturally infested R. microplus strongly suggested that the effect of the vaccine was the result of the antibody response in immunized cattle. In conclusion, it was demonstrated that the peptide Subolesin induced a specific immune response in cattle under field conditions, resulting in reduced R. microplus populations in subsequent generations. Finally, integrated tick control must consider anti-tick vaccines as a cost-effective, sustainable, and successful tool for controlling cattle tick infestations.

Interfering with cholesterol metabolism impairs tick embryo development and turns eggs susceptible to bacterial colonization

Cholesterol is a known precursor of arthropod molecules such as the hormone 20-hydroxyecdysone and the antimicrobial boophiline, a component of tick egg wax coat. Because the cholesterol biosynthetic pathway is absent in ticks, it is necessarily obtained from the blood meal, in a still poorly understood process. In contrast, dietary cholesterol absorption is better studied in insects, and many proteins are involved in its metabolism, including Niemann-Pick C (NPC) transporter and acyl-CoA:cholesterol acyltransferase (ACAT), as well as enzymes to convert between free cholesterol and esterified cholesterol. The present work addresses the hypothesis that tick viability can be impaired by interfering with cholesterol metabolism, proposing this route as a target for novel tick control methods. Two drugs, ezetimibe (NPC inhibitor) and avasimibe (ACAT inhibitor) were added to calf blood and used to artificially feed Rhipicephalus microplus females. Results show that, after ingesting avasimibe, tick reproductive ability and egg development are impaired. Also, eggs laid by females fed with avasimibe did not hatch and were susceptible to Pseudomonas aeruginosa adhesion and biofilm formation in their surfaces. The immunoprotective potential of ACAT against ticks was also accessed using two selected ACAT peptides. Antibodies against these peptides were used to artificially feed female ticks, but no deleterious effects were observed. Taken together, data presented here support the hypothesis that enzymes and other proteins involved in cholesterol metabolism are suitable as targets for tick control methods.

Gene cloning, analysis and effect of a new lipocalin homologue from Haemaphysalis longicornis as a protective antigen for an anti-tick vaccine

Haemaphysalis longicornis is distributed worldwide and transmits a variety of pathogens, causing human and animal disease. Use of chemical acaricides, as a primary tick control method, has several disadvantages, including acaricide resistance, environmental damage and residue accumulation in livestock. Development of a livestock vaccination aimed at a tick protective antigen could be an effective, labor-saving and environmentally-friendly method of reducing tick infestation and transmission of tick-borne pathogens. Lipocalins are low molecular weight proteins that play important roles in blood feeding, immune response and reproduction in ticks. In our study, the open reading frame (ORF) of a lipocalin homologue from H. longicornis (HlLIP) was successfully cloned, which consisted of 387 bp encoding a protein of 128 amino acids. The HlLIP protein sequence showed a close sequence homology with Ixodes persulcatus lipocalin. The HlLIP gene was constitutively detected in all developmental stages and in all tissues of the unfed female tick. The ORF of the HlLIP gene was sub-cloned into pET-32a (+) to obtain the recombinant protein (rHlLIP) and its immunogenicity was comfirmed by western blot. A vaccination trial on rabbits against H. longicornis infestation demonstrated that the rHlLIP protein could significantly prolong the period of tick blood feeding, and reduce tick engorged weight, oviposition and egg hatching rate. The vaccination efficacy of the rHlLIP protein was 60.17 % based on engorged weight, oviposition and egg hatching rate of ticks. The results obtained in this study demonstrate that rHlLIP protein is a promising antigen that could potentially be developed as a vaccine against H. longicornis infestation.

Immunoprotection evaluation of the recombinant N-terminal domain of Cys-loop receptors against Rhipicephalus (Boophilus) microplus tick infestation

Rhipicephalus (Boophilus) microplus ticks are obligatory hematophagous ectoparasites of cattle and act as vectors for disease-causing microorganisms. Conventional tick control is based on the application of chemical acaricides; however, their uncontrolled use has increased resistant tick populations, as well as food and environmental contamination. Alternative immunological tick control has shown to be partially effective. Therefore, there is a need to characterize novel antigens in order to improve immunological protection. The aim of this work was to evaluate Cys-loop receptors as vaccine candidates. N-terminal domains of a glutamate receptor and of a glycine-like receptor were recombinantly produced in Escherichia coli. Groups of BALB/c mice were independently immunized with four doses of each recombinant protein emulsified with Freund’s adjuvant. Both vaccine candidates were immunogenic in mice as demonstrated by western blot analysis. Next, recombinant proteins were independently formulated with the adjuvant Montanide ISA 50 V2 and evaluated in cattle infested with Rhipicephalus microplus tick larvae. Groups of three European crossbred calves were immunized with three doses of each adjuvanted protein. ELISA test was used to evaluate the IgG immune response elicited against the recombinant proteins. Results showed that vaccine candidates generated a moderate humoral response on vaccinated cattle. Vaccination significantly affected the number of engorged adult female ticks, having no significant effects on tick weight, egg weight and egg fertility values. Vaccine efficacies of 33% and 25% were calculated for the glutamate receptor and the glycine-like receptor, respectively.

In-vitro anticandidial efficacy of tick egg wax from Hyalomma marginatum, Rhipicephalus bursa and Dermacentor marginatus

Objective: In the previous studies, the antibacterial, antifungal, and antiviral efficacy of the tick egg wax-coating of certain tick species wereexamined and some significant results were obtained. However, related researches and studied tick species are limited. There are hundredsof tick species, and it is well known that the antimicrobial efficacy of the wax is closely related to the species. The aim of this study was toinvestigate the in-vitro anticandidial efficacy of the egg waxes belonging to three tick species, which have not been studied before and havequite different biological and ecological differences.Methods: In the study, the egg waxes of the tick species, Hyalomma marginatum, Rhipicephalus bursa, and Dermacentor marginatus, wereused on Candida albicans ATCC10231, Candida parapsilosis ATCC 22019, and Candida tropicalis ATCC 750. Antimycotic susceptibility test wascarried out in accordance with the Clinical and Laboratory Standards Institute (CLSI) recommendations using the M27-A3 microdilution method.Results: It was determined that the wax of Rhipicephalus bursa has inhibitory effect on Candida tropicalis ATCC 750 in a particular concentration,and no significant effects were observed in other trials.Conclusion: Anticandidial effect obtained from the egg wax of R. bursa can be associated with some distinctive biological characteristics, and itwas concluded that the detailed studies with different tick species might yield significant results for the discovery of new generation antifungals.

Catalogue of stage-specific transcripts in Ixodes ricinus and their potential functions during the tick life-cycle

BackgroundThe castor bean tick Ixodes ricinus is an important vector of several clinically important diseases, whose prevalence increases with accelerating global climate changes. Characterization of a tick life-cycle is thus of great importance. However, researchers mainly focus on specific organs of fed life stages, while early development of this tick species is largely neglected.MethodsIn an attempt to better understand the life-cycle of this widespread arthropod parasite, we sequenced the transcriptomes of four life stages (egg, larva, nymph and adult female), including unfed and partially blood-fed individuals. To enable a more reliable identification of transcripts and their comparison in all five transcriptome libraries, we validated an improved-fit set of five I. ricinus-specific reference genes for internal standard normalization of our transcriptomes. Then, we mapped biological functions to transcripts identified in different life stages (clusters) to elucidate life stage-specific processes. Finally, we drew conclusions from the functional enrichment of these clusters specifically assigned to each transcriptome, also in the context of recently published transcriptomic studies in ticks.ResultsWe found that reproduction-related transcripts are present in both fed nymphs and fed females, underlining the poorly documented importance of ovaries as moulting regulators in ticks. Additionally, we identified transposase transcripts in tick eggs suggesting elevated transposition during embryogenesis, co-activated with factors driving developmental regulation of gene expression. Our findings also highlight the importance of the regulation of energetic metabolism in tick eggs during embryonic development and glutamate metabolism in nymphs.ConclusionsOur study presents novel insights into stage-specific transcriptomes of I. ricinus and extends the current knowledge of this medically important pathogen, especially in the early phases of its development.

Acaricidal properties of hemp (Cannabis sativa L.) essential oil against Dermanyssus gallinae and Hyalomma dromedarii

The use of conventional pesticides in pest management is facing issues such as developing resistance in pests, environmental pollution and impact on human health, together with regulatory hurdles for approval and marketing of new eco-friendly pesticides to comply with the global trend for residue-free foodstuff. In this framework, botanical pesticides represent valuable alternative products to be exploited. Hemp (Cannabis sativa L.) is an eco-friendly, multipurpose crop that is known for its resistance against insects and parasites. This property is assured by the production of bioactive secondary metabolites such as terpenes and cannabinoids. Notably, the hemp essential oil (EO) contains several terpenoid compounds endowed with pesticide properties. On this basis, in the present work we assayed the toxicity of hemp EO on two ectoparasites of veterinary importance, i.e. Dermanyssus gallinae De Geer and Hyalomma dromedarii Koch. In order to identify the EO chemical constituents responsible for the toxicity on the two ectoparasites, the main monoterpenes and sesquiterpenes of hemp EO, namely α-pinene, myrcene, (E)-caryophyllene and α-humulene were tested as well. Mite contact toxicity assays were carried out at the concentrations of 5, 10, 20, 50, 100 and 200 μg/cm3. Tick larvicidal and ovicidal assays were done testing 0.5, 1, 2, 5, 10, 20, and 50 μg/mL of the hemp EO and its main components. Results from mite contact toxicity showed that hemp EO was toxic to D. gallinae with LC50 values of 47.1 μg/mL. Larvicidal and ovicidal assays revealed the promising activity of the EO against tick larvae and eggs. Among all the tested compounds, (E)–caryophyllene and α-humulene were the most toxic for both ticks and mites, showing LC50 values lower than the whole EO. Myrcene was moderately toxic, with LC50 values higher than the whole EO, whereas α-pinene showed weak acaricidal activity. Taken together our results remarked the potential of hemp EO as a potential botanical acaricide in pest management programs and food production. The industrial scalability is assured by the great availability of land for the cultivation of hemp and its low cost of production.

Rotational grazing approaches reduces external and internal parasite loads in cattle

We tested whether holistic planned grazing (HPG) and four-camp grazing (FCG) rotational grazing approaches influence beef cattle parasites counts compared with continuous, season-long (SLG) grazing. We expected that parasite counts would increase linearly with increasing camp occupancy by cattle from 1 d (70-camp, HPG) to 21–28 d (four-camp, FCG) to 180 d (one-camp per season, SLG). Tick and faecal egg counts were observed across seasons on 30 steers raised on a private farm in Cedarville, South Africa. Tick species identified were Rhipicephalus evertsi evertsi, Rhipicephalus (Boophilus) decoloratus, Hyalomma spp. and Amblyomma hebreaum with respective prevalences of 32%, 29%, 20% and 19%. Unidentified roundworms had the highest faecal worm egg counts (81.2%) followed by Coccidia (16.4%), Nematodirus (1.2%) and strongyles (1.2%). Overall, prevalence and mean counts for ticks and faecal worm eggs were highest in the hot wet season, with the SLG having greater (P ≤ 0.05) values than either of the rotational approaches. However, increasing camp number and animal densities above four camps did not reduce (P > 0.05) parasite loads compared with HPG. Current results suggest that rotational grazing is a potential strategy to reduce livestock losses caused by high tick and worm loads in cattle, especially in the hot wet season.

Establishing a Cultivable Cell Line of the Tick Dermacentor marginatus

Owing to the changes in the general ecological situation in Russia, livestock losses from ovine anaplasmosis have rapidly increased in recent years. The development of a vaccine against this disease is therefore all the more relevant. A continuous culture of tick cells could be used as an appropriate substrate for producing biomass of the pathogen of ovine anaplasmosis, Anaplasma ovis, for the purpose of manufacturing a cell-cultural inactivated vaccine. Such a continuous cell line of the tick Dermacentor marginatus, the definitive reservoir host of A. ovis, has been obtained by cultivation of homogenized tick eggs on a modified Leibovitz medium L15. The established cell line DM-77 has an undifferentiated phenotype: the cells are rounded, with large nuclei and well-visible nucleoli. By the end of the study, the cell line was passaged eight times and did not express signs of growth rate decrease. The duplication time was 2.8 ± 0.3 days for cultivation in a medium with 10% fetal serum at 32°C.

Control of bovine tick [Rhipicephalus (Boophilus) microplus] with Brunfelsia uniflora leaf extract

Bovine tick has caused losses in livestock production profitability in Brazil. However, tick control has caused resistance of these ectoparasites against utilized acaricides. Alternative tick controls have been utilizing plants as sources of effective botanical acaricides. Brunfelsia uniflora is a Brazilian plant with antimicrobial and antioxidant activity; however, there are no reports on its acaricidal activity. Therefore, this study aimed to evaluate the chemical composition of B. uniflora leaf ethanolic extract and its efficiency to control bovine tick in vitro and free-living stage ex situ. The crude leaf extract was analyzed by gas chromatographer coupled to mass spectrometer (GC-MS) with identification of 17 compounds. The major compounds were phytol (22.96%), 9,12,15-octadecatrienoic acid, ethyl ester (Z,Z,Z) (21.18%), hexadecanoic acid, ethyl ester (12.74%) and vitamin E (8.77%). The crude extract presented acaricidal activity in vitro against ingurgitated adult females, larvae and eggs of bovine tick. The LC99.9 for larvae was 103.21 mg mL-1 in in vitro tests and was 100% efficient for ex situ larva test (free-living stage). B. uniflora leaf extract is an alternative for the control of the bovine tick cycle, mainly in the free-living stage (non-parasitic stage) under field conditions.

Relationships of Salinity, Relative Humidity, Mud Flat Fiddler Crabs, Ants, and Sea Ox-Eye Daisy With Ixodid Distribution and Egg Survival on the South Texas Coastal Plains.

The South Texas coastal plains are mostly dominated by mesquite-thorn scrub from the Mexican border to cattle ranches extending north from Willacy Co. A wildlife corridor on the plains, composed of natural habitat, supports hosts of many ixodid species. Occasional wind (not lunar) tides and infrequent storm surges inundate coastal plain areas with hypersaline water from the Lower Laguna Madre, creating large areas of saline soil. Laboratory and field experiments and observations were used to identify relationships between salinity and other abiotic and biotic factors that influence ixodid distribution. Exposure of lone star tick, Amblyomma americanum (L.), and Rhipicephalus microplus (Canestrini) eggs to hypersaline water is lethal. Although intermittent hypersaline flooding kills ixodid eggs, saline soil was not particularly toxic. When relative humidity is relatively low, desiccation causes high egg mortality on dry soil, regardless of salinity. Substantial year-round populations of mud flat fiddler crabs, Uca rapax (Smith) (Decopoda: Ocypodidae), occur on saline soil and eliminated ≈80% of A. americanum egg masses overnight. On saline and low-salinity soils predatory formicids, including the red imported fire ant, Solenopsis invicta (Buren), were indifferent to the eggs. Saline soils were dominated by the sea ox-eye daisy, Borrichia frutescens (L.) DC, and its color allowed production of a GIS-based map. At least 24.4% of the wildlife corridor supports heavy stands of B. frutescens which is indicative of high U. rapax populations. Ixodid populations were negligible on heavy B. frutescens stands because of associated salt water toxicity, desiccation, and predation by U. rapax on eggs.

Molecular Assessment of Anaplasma marginale in Bovine and Rhipicephalus (Boophilus) microplus Tick of Endemic Tribal Belt of Coastal South Gujarat, India.

This study described the detection, prevalence and phylogeny of Anaplasma marginale in the bovine (cattle and buffaloes) and Rhipicephalus (Boophilus) microplus tick belonged to the tribal area of coastal South Gujarat, India, by amplifying 576bp of major surface protein (msp) 5 gene using custom designed primers in the polymerase chain reaction (PCR). The PCR detection limit was up to 20 parasites/µl of blood in sensitivity experiment, and observed 100% specificity against Trypanosoma evansi, Babesia bigemina and Theileria annulata. Prevalence rate of the A. marginale in the bovine (n = 211)) was 18.48% and 6.64% (p < 0.05) as per the PCR and Giemsa stained blood smear, respectively. Febrile animals (35%) observed significantly (p < 0.05) higher incidence rate than the non-febrile (14.62%). The amplified msp5 had single cut site for the EcoR1 enzyme, upon digestion yielded two fragments of 365 and 211bp on 1.0% agarose gel. The current sequence (KC811329) showed 100% homology and 1064 total score with the published nucleotide sequences of msp5 of A. marginale in the NCBI-BLAST study. Monophyletic relationship was observed with high bootstrap proportion (>76% in Neighbor-Joining/ Maximum Likelihood) between the current and published nucleotide sequences in the phylogeny. Twenty out of 39 A. marginale infected bovine recorded R. (B.) microplus on their body surface, out of which 18 had detected the infection. The rickettsia was in 55%, 65% and 25% of anterior half, posterior half and egg of tick, respectively. The test detected A. marginale in a carrier, pre-symptomatic and symptomatic vertebrate hosts (cattle and buffalo) and different body parts of the starved R. (B.) microplus including its egg. The current genotype could be an explanation for the frequent outbreaks of bovine anaplasmosis in the targeted areas.

Evidence for transovarial transmission of tick-borne rickettsiae circulating in Northern Mongolia.

Transstadial transmission of tick-borne rickettsiae has been well documented. Few studies, however, have evaluated the role of transovarial transmission of tick-borne rickettsiae, particularly in nature within the host-vector ecosystem. This cross-sectional study aimed to understand the role of transovarial transmission of tick-borne rickettsiae among feeding ticks at different life stages. Tick eggs laid by engorged wild-caught adult female ticks were pooled and tested for Rickettsia spp. and Anaplasma/Ehrlichia spp. using molecular techniques, while adult fed ticks were tested individually. Additionally, larval and nymphal ticks were collected in the wild from small mammals, pooled and tested for Rickettsia spp. and Anaplasma/Ehrlichia spp. There were 38 fed adult and 618 larvae/nymphs (60 pools total) Dermacentor spp. ticks collected from livestock and rodents. All individual adult ticks and tick pools were positive for Rickettsia spp. While none of the larvae/nymphs were positive for Anaplasma/Ehrlichia spp., two adult fed ticks were positive. Rickettsia spp. DNA was detected in 91% (30/33) of the pooled eggs tested, and one pool of eggs tested positive for Anaplasma/Ehrlichia spp. Sequencing data revealed Rickettsia spp. shared ≥99% identity with R. raoultii ompA. Anaplasma/Ehrlichia spp. shared ≥89% identity with A. ovis 16S ribosomal RNA. This study identified potential transovarial transmission of Rickettsia spp. and Anaplasma spp. among D. nuttalli ticks. Additional studies are needed to further assess the proportion of transovarial transmission occurring in nature to better understand the burden and disease ecology of tick-borne rickettsiae in Mongolia.

Immunofluorescent detection in the ovary of host antibodies against a secretory ferritin injected into female Haemaphysalis longicornis ticks

Due to the continuous threat of ticks and tick-borne diseases to human and animal health worldwide, and the drawbacks of chemical acaricide application, many researchers are exploring vaccination as an alternative tick control method. Earlier studies have shown that host antibodies can circulate in the ticks, but it has not been confirmed whether these antibodies can be passed on to the eggs. We previously reported that ticks infesting rabbits immunized with a recombinant secretory ferritin of Haemaphysalis longicornis (HlFER2) had reduced egg production and hatching. Here we attempted to detect the presence of antibodies against HlFER2 in the ovary and eggs of female ticks through immunofluorescent visualization. Purified anti-HlFER2 antibodies or rabbit IgG for control was directly injected to engorged female H. longicornis. Ovaries and eggs after oviposition were collected and prepared for an indirect immunofluorescent antibody test. Positive fluorescence was detected in ovaries one day post-injection of anti-HlFER2 antibodies. Through silencing of Hlfer2 gene, we also determined whether the injected antibodies can specifically bind to native HlFER2. Immunofluorescence was observed in the oocytes of dsLuciferase control ticks injected with anti-HlFER2 antibodies, but not in the oocytes of Hlfer2-silenced ticks also injected with anti-HlFER2 antibodies. Our current findings suggest that host antibodies can be passed on to the oocytes, which is significant in formulating a vaccine that can disrupt tick reproduction.