Rhipicephalus Annulatus Research Articles

Morphological characterization of ticks of the genus <em>Rhipicephalus (Boophilus)</em> based on geometric morphometry: the case of the Savannah District in Côte d’Ivoire

The introduction of the invasive tick Rhipicephalus (Boophilus) microplus in Côte d'Ivoire has led to a change in the population of ticks of the genus Rhipicephalus (Boophilus). Thus, this study aims to characterize morphologically the tick species of the genus Rhipicephalus (B.) by geometric morphometry. It consisted of collecting all ticks from cattle in 74 farms in the Savanes District. The collected ticks were identified in the laboratory and, after identification, only non-gorged adult ticks of the genus Rhipicephalus (B.) were retained for morphometric characterisation. A total of 394 ticks were examined under a digital microscope, images were digitised using the online program XYOM and the data were analysed. This study revealed that males of each species have a smaller average size than females. It also showed a variation in mean size in all species except for the females of Rhipicephalus (B.) decoloratus and Rhipicephalus (B.) geigyi whose mean sizes did not differ. Geometric morphometry allowed the separation of Rhipicephalus (B.) annulatus males from other males. In females, Rhipicephalus (B.) geigyi and Rhipicephalus (B.) microplus were distinguished from each other and from other females.

An investigation of the acaricidal activity of benzyl alcohol on Rhipicephalus annulatus and Rhipicephalus sanguineus and its synergistic or antagonistic interaction with commonly used acaricides.

The most economically significant ectoparasites in the tropics and subtropics are ixodid ticks, especially Rhipicephalus annulatus and Rhipicephalus sanguineus. Years of extensive use of the readily available acaricides have resulted in widespread resistance development in these ticks, as well as negative environmental consequences. Benzyl alcohol (BA) has been frequently used to treat pediculosis and scabies, and it may be an effective alternative to commonly used acaricides. The main aim of the present study was to evaluate the acaricide activity of BA and its combination with the regularly used chemical acaricides against R. annulatus and R. sanguineus. Different concentrations of BA alone and in combination with deltamethrin, cypermethrin and chlorpyrifos were tested in vitro against adult and larvae of both tick species. The results showed that BA is toxic to R. annulatus and R. sanguineus larvae, with 100% larval mortality at concentrations of ≥50 mL/L, and LC50 and LC90 attained the concentrations of 19.8 and 33.8 mL/L for R. annulatus and 18.8 and 31.8 mL/L for R. sanguineus, respectively. Furthermore, BA in combination with deltamethrin, cypermethrin and chlorpyrifos exhibited synergistic factors of 2.48, 1.26 and 1.68 against R. annulatus larvae and 1.64, 11.1 and 1.14 against R. sanguineus larvae for deltamethrin + BA, cypermethrin + BA and chlorpyrifos + BA, respectively. BA induced 100% mortality in adult R. annulatus at concentrations of ≥250 mL/L with LC50 and LC90 reached the concentrations of 111 and 154 mL/L, respectively. Additionally, BA had ovicidal activity causing complete inhibition of larval hatching at 100 mL/L. The combination of BA with deltamethrin and cypermethrin increased acetylcholinesterase inhibition, whereas the combination of BA with chlorpyrifos decreased glutathione (GSH) activity and malondialdehyde levels. In the field application, the combination of BA 50 mL/L and deltamethrin (DBA) resulted in a significant reduction in the percentage of ticks by 30.9% 28 days post-treatment when compared with groups treated with deltamethrin alone. In conclusion, BA causes mortality in laboratory and field studies alone and in combination with cypermethrin or deltamethrin. BA can be used for control of ticks of different life stages, that is, eggs and larvae, through application to the ground.

Prevalence and Seasonal Dynamics of Rhipicephalus annulatus in Cattle and Buffaloes in Menoufia Governorate, Egypt.

Prevalence and Seasonal Dynamics of Rhipicephalus annulatus in Cattle and Buffaloes in Menoufia Governorate, Egypt.

Biological synthesis of nickel nanoparticles using extracellular metabolites of Bacillus sphaericus: Characterization and vector-borne disease control applications

In this study, we use extracellular metabolites of Bacillus sphaericus culture for the biosynthesis of nickel nanoparticles (BS@NiNPs) and potential larvicidal activity against Anopheles subpictus and Culex quinquefasciatus as well as against Rhipicephalus (Boophilus) annulatus (adult cattle tick). The extracellular metabolites derived from B. sphaericus culture acts as strong reducing and capping agents, allowing biosynthesis of the BS@NiNPs. Characterization of the synthesized NiNPs was carried out using various techniques, including UV–vis spectroscopy, atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) and X-ray diffraction (XRD). The FTIR spectroscopy analysis revealed significant peaks at specific wavenumbers (3435, 2923, 1646, 1406, and 1115 cm−1), indicating the presence of functional groups from biomolecules involved in the synthesis of BS@NiNPs. XRD analysis confirms well-defined peaks observed at 2θ = 31.72°, 45.40°, 56.43°, and 75.32°, which correspond to the lattice planes of 100, 101, 102, and 103 reflections, respectively. SEM and TEM images showed that the NiNPs exhibited spherical to oval shapes with clustered morphology with an average diameter of the grain size is about 23 ± 2.00. The BS@NiNPs exhibited significant parasitic action against A. subpictus and C. quinquefasciatus as well as adult cattle tick R. (B) annulatus. It is noteworthy that bacterial pathogens such as Bacillus species are commonly used for vector bio-control management due to their spore-forming characteristics. Therefore, the toxicity of BS@NiNPs-treated mosquito larvae and cattle ticks was analyzed for stress-related enzyme activities, including carboxylesterases, β-glucosidases, and glutathione S-transferases. In summary, our work shows that BS@NiNPs have the potential to be an efficient larvicide against ticks and mosquito larvae. The results of this study help to design environmentally benign and long-lasting methods for biological control, addressing the problems posed by vector-borne diseases.

Molecular Detection of Francisella tularensis Isolated from Ticks of Livestock in Kurdistan Region, Iraq.

Background: Francisella tularensis is a Gram-negative bacterium that causes tularemia in both human and animals. Tularemia is a potential serious zoonotic disease that is transmitted by different routes, including tick bites. Materials and Methods: This study deals with investigating the prevalence of F. tularensis in the ticks of local animal farms in Kurdistan region since the farmers are normally in close contact with livestock. We used molecular methods for this purpose. A total of 412 tick and 126 blood samples were gathered from goat, sheep, and cow flocks. The existence of F. tularensis 16Sr RNA gene was examined in the samples using nested-PCR technique. Results: In the animal blood specimens, no F. tularensis was found. The incidence of F. tularensis was 1.7% (7 out of 412) in the tick samples, representing a very lower possibility of tuleremia infection. Moreover, the two subspecies of F. tularensis novicida and holarctica were identified based on the sequencing of pdpD and RD genes, respectively. The F. tularensis subsp. novicida was isolated from four species of ticks, Hyalomma anatolicum, Rhipicephalus annulatus, Rhipicephalus sanguineus, and Ornithodoros spp., whereas the F. tularensis subsp. holarctica was isolated from Haemaphysalis parva and Hyalomma dromedarii species of ticks. Conclusion: Although its prevalence is very low, the isolation of F. tularensis subsp. holarctica from the ticks of farm animals suggests possible transmission of Tularemia through tick bite in Kurdistan region of Iraq. Ref: IR-UU-AEC-3/22.

Transcriptome Profiling of Rhipicephalus annulatus Reveals Differential Gene Expression of Metabolic Detoxifying Enzymes in Response to Acaricide Treatment.

Ticks are hematophagous ectoparasites of economic consequence by virtue of being carriers of infectious diseases that affect livestock and other sectors of the agricultural industry. A widely prevalent tick species, Rhipicephalus (Boophilus) annulatus, has been recognized as a prime vector of tick-borne diseases in South Indian regions. Over time, the use of chemical acaricides for tick control has promoted the evolution of resistance to these widely used compounds through metabolic detoxification. Identifying the genes related to this detoxification is extremely important, as it could help detect valid insecticide targets and develop novel strategies for effective insect control. We performed an RNA-sequencing analysis of acaricide-treated and untreated R. (B.) annulatus and mapped the detoxification genes expressed due to acaricide exposure. Our results provided high-quality RNA-sequenced data of untreated and amitraz-treated R. (B.) annulatus, and then the data were assembled into contigs and clustered into 50,591 and 71,711 uni-gene sequences, respectively. The expression levels of the detoxification genes across different developmental stages of R. (B.) annulatu identified 16,635 transcripts as upregulated and 15,539 transcripts as downregulated. The annotations of the differentially expressed genes (DEGs) revealed the significant expression of 70 detoxification genes in response to the amitraz treatment. The qRT-PCR revealed significant differences in the gene expression levels across different life stages of R. (B.) annulatus.

Molecular characterization of Amblyomma geoemydae using CO1 mitochondrial gene to validate phenotypic taxonomical evaluation.

Animal ectoparasites are linked to the spread of serious medical and veterinary important pathogens. Our research intends to close the knowledge gap concerning the numerous ectoparasites that inhabit animals in Wayanad. Ectoparasites in animals brought to the veterinary dispensaries in Wayanad were retrieved and identified morphologically and molecularly. Using a high-quality stereomicroscope, the taxonomic features of the four following species were examined and identified: Haemaphysalis bispinosa, Rhipicephalus annulatus, R. microplus, and Amblyomma geoemydae. The important disease vector A. geoemydae was reported for the first time in Kerala. The important phenotypic characters of the highlighted species A. geoemydae are the edge of the basis capituli is circular without cornua, and the hypostomal dental formula is 2/2. The taxonomically identified four species were subjected to CO1 gene sequence analysis. The evolutionary relationship was inspected through the neighbour-joining method, and the phylogenetic tree was built through the Maximum Likelihood method. The present study has also estimated the diversity index of R. microplus, R. annulatus, H. bispinosa, and A. geoemydae. Among them, R. microplus 0.36638 have reported with the maximum diversity index score. The significance of the study is the presence of Lyme disease vector A. geoemydae, in the Wayanad District of Kerala, and it is the first report of the species from where an outbreak of Lyme disease occurred in 2013.

Synthesis of Carvacrol-Loaded Invasomes Nanoparticles Improved Acaricide Efficacy, Cuticle Invasion and Inhibition of Acetylcholinestrase against Hard Ticks.

Carvacrol is a monoterpenoid phenol found in many essential oils that has antibacterial, antifungal and antiparasitic activities. Drug loaded-invasome systems are used to deliver drugs utilizing nanoparticles to improve bioavailability, efficacy, and drug release duration. As a result, the present study developed carvacrol-loaded invasomes and evaluated their acaricidal effect against Rhipicephalus annulatus (cattle tick) and Rhipicephalus sanguineus (dog tick). Carvacrol loaded-invasome (CLI) was prepared and characterized using UV/Vis spectrophotometer, zeta potential measurements, Scanning Transmission Electron Microscopy (STEM), Fourier Transform Infrared (FT-IR) Spectroscopy, and Differential Scanning Calorimetry Analysis. CLI (5%) induced significant mortality (100%) in R. annulatus adult ticks with LC50 of 2.60%, whereas the LC50 of pure carvacrol was 4.30%. Carvacrol and CLI were shown to have a significant larvicidal action on both tick species, with LC50s of 0.24 and 0.21% against R. annulatus and 0.27 and 0.23% against R. sanguineus, respectively. Carvacrol and CLI (5%) induced significant repellent activities for 24 h against R. annulatus and R. sanguineus, as evidenced by the rod method and the petri-dish selective area choice method, respectively. High-performance liquid chromatography (HPLC) demonstrated that the CLI form had 3.86 times the permeability of pure carvacrol. Moreover, carvacrol and CLI inhibited acetylcholinesterase activity and decreased glutathione and malonedealdehyde levels in the treated ticks. In conclusion, invasomes significantly improved adulticidal and repellency activities of carvacrol against both tick species.

MALDI-TOF MS identification of cattle ticks from Cameroon

MALDI-TOF MS has recently been proposed as an accurate tool for arthropod identification, including ticks. In this study, we evaluate and confirm the ability of MALDI-TOF MS, to identify different tick species collected in Cameroon, considering other lines of evidence (morphology and molecular). A total of 1483 adult ticks were collected from cattle in five distinct sites in the Western Highland of Cameroon. Because of engorged status and/or absence of some morphological criteria, some Ixodes spp. and Rhipicephalus spp. were identified to the genus level only. Among those, 944 ticks (543 males and 401 females) were selected for the current work. They were classified into 5 genera and 11 species: Rhipicephalus (Boophilus) microplus (31.7%), Rhipicephalus lunulatus (26%), Amblyomma variegatum (23%), Rhipicephalus sanguineus s.l. (4.8%), of Haemaphysalis leachi group (4.6%), Hyalomma truncatum (2.6%), Hyalomma rufipes (1.7%), Rhipicephalus muhsamae (1.1%), Rhipicephalus (Boophilus) annulatus (0.6%), Rhipicephalus (Boophilus) decoloratus (0.3%), Ixodes rasus (0.1%), Ixodes spp. (0.2%) and Rhipicephalus spp. (3.3%). Tick legs were subjected to MALDI-TOF MS analyzes, and the spectra of 929 (98.4%) specimens were of good quality. Analysis of these spectra provided intra-species reproducibility and interspecies specificity of MS profiles obtained from the different species. Our in-house MALDI-TOF MS arthropod database was upgraded with spectra from 44 specimens of 10 different tick species. Blind testing of good quality spectra revealed that 99% agreed with the morphological identification. Of these, 96.9% had log score values (LSVs) between 1.73 and 2.57. MALDI-TOF MS also allowed to correct the morphological misidentification of 7 ticks, and to identify 32 engorged ticks that were not morphologically identifiable to the species level. This study supports MALDI-TOF MS as a reliable tool for tick identification and provides new data on tick species identification in Cameroon.

Molecular prevalence of Anaplasma marginale in ruminants and Rhipicephalus ticks in northern Pakistan.

Anaplasma marginale is the most prevalent tick-borne haemoparasite of cattle and causes huge economic losses to the dairy industry worldwide. This study aimed to determine the occurrence of A. marginale infection in blood and tick samples collected from livestock animals in the districts located in Khyber Pakhtunkhwa (KPK), Pakistan. A total of 184 blood and 370 tick samples were included in this study. It has never been reported that sheep, goats, and cattle in Tank, Ghulam Khan, Birmil and Miran Shah areas were infected with A. marginale. All samples of blood and ticks were collected through random sampling from March 2021 to January 2022 from cattle, sheep and goats and screened through PCR for anaplasmosis by using primer pairs of Anaplasma spp. Three hundred and seventy ticks were collected from infested hosts (120/184, 64.21%). Among the four morphologically identified tick species, the highest occurrence was recorded for Rhipicephalus sanguineus (n=138, 37.29%), followed by Rhipicephalus microplus (n=131, 35.4%), Rhipicephalus annulatus (n=40, 10.81%), Hyalomma anatolicum (n=31, 8.37%), and Hyalomma marginatum (n=30, 8.1%). The occurrence of female tick was highest (n=160, 43.24%), followed by nymphs (n=140, 37.38%) and males ticks (n=70, 18.9%). Among these ticks, A. marginale was detected in female ticks of R. microplus, and R. sanguineus. Molecular identification of A. marginale was confirmed in 120 out of 184 blood samples and 6 out of 74 tick samples. Overall, occurrence of A. marginale in blood and tick samples was found to be 65.21% and 8.1% respectively. Species-wise occurrence in blood samples of goats were 71.11% followed by sheep 68.31% and cattle 50%. Specie-wise occurrence of A. marginale in tick samples of cattle were 12.5% followed by goats 6.89%. The obtained sequence showed similarity with A. marginale reported from Kenya and USA. We report the first PCR based detection of A. marginale infection in blood samples and in R. sanguineus ticks of goats simultaneously.

Preliminary Study on Hard Ticks ( Acari: Ixodidae) of Sheep in Some Areas of Thamar Governorate, Yemen

The objective of this study was to identify and determine the prevalence of tick species infesting sheep in some areas of Thamar governorate, Yemen. A total of 392 indigenous sheep breeds of either sex and different age were randomly selected and examined for presence of ticks using standard parasitological techniques from December, 2010 to May, 2011. The results revealed that the overall prevalence of tick infestations on sheep was 43.37 %. Of total 875 ticks collected, Seven species of ixodid ticks were identified. The species on hierarchy of overall prevalence abundance were Rhipicephalus sanguineus (13.01%), Rhipicephalus (Boophilus) decoloratus (9.69%), Rhipicephalus evertsi evertsi (5.87 %), Hyalomma marginatum (4.59 %), Amblyomma variegatum (4.34%), Rhipicephalus (Boophilus) annulatus (3.06%), Haemaphysalis sulcata (2.04%). Rhipicephalus (Boophilus) decoloratus species is recorded for first time in Thamar governorate and Yemen as well as. Statistically, there was significance difference (P

Acaricidal Activity of Tea Tree and Lemon Oil Nanoemulsions against Rhipicephalus annulatus.

Tick infestation is a serious problem in many countries since it has an impact on the health of animals used for food production and pets, and frequently affects humans. Therefore, the present study aimed to investigate the acaricidal effects of nanoemulsions of essential oils of Melaleuca alternifolia (tea tree, TT) and Citrus limon (lemon oil, CL) against the different stages (adult, eggs, and larvae) of deltamethrin-resistant Rhipicephalus annulatus ticks. Three forms of these oils were tested: pure oils, nanoemulsions, and a binary combination. Tea tree and lemon oil nanoemulsions were prepared, and their properties were assessed using a zeta droplet size measurement and a UV-Vis spectrophotometer. The results showed that TT and CL exhibited higher adulticidal effects in their pure forms than in their nanoemulsion forms, as demonstrated by the lower concentrations required to achieve LC50 (2.05 and 1.26%, vs. 12.8 and 11.4%, respectively) and LC90 (4.01% and 2.62%, vs. 20.8 and 19.9%, respectively). Significant larvicidal activity was induced by the TTCL combination, and LC50 was reached at a lower concentration (0.79%) than that required for the pure and nanoemulsion forms. The use of pure CL oil was found to have the most effective ovicidal effects. In conclusion, pure TT and CL have potent acaricidal effects against phenotypically resistant R. annulatus isolates. It is interesting that the activity levels of TT and CL EOs' binary and nanoemulsion forms were lower than those of their individual pure forms.

Morphological and molecular characterization of Rhipicephalus microplus and Rhipicephalus annulatus from selected states of southern India

Ticks of the genus Rhipicephalus infesting cattle are the primary animal pests responsible for the annual economic loss of billions of dollars. Due to the morphological resemblance among the members of the Rhipicephalus (Boophilus) genus, species identification is very difficult. In this study, the adult R. annulatus and R. microplus ticks from two south Indian states viz., Kerala and Karnataka were subjected to morphological and molecular characterization. The R. microplus isolates from south India differed morphologically from true R. microplus clade A ticks. The ventral spur on the first pedipalp observed in male R. microplus was similar to that of R. australis. The phylogenetic analysis revealed that the R. microplus from these states clustered with R. microplus clade C. The mitochondrial cytochrome c oxidase I (COI) was identified as the preferred molecular marker compared to the internal transcribed spacer 2 (ITS2). The interspecific divergence between R. microplus and R. annulatus isolates from South India was 7.9 per cent based on COI. Moreover, based on COI, the R. microplus isolates revealed higher intraspecific divergence (2.9%) than R. annulatus (1%). The ITS2 sequences failed to differentiate R. microplus and R. annulatus.

Molecular Investigation of Coxiella Burnetii in Hard Ticks Collected From Some Livestock in the Sistan Region

Background and Objectives Coxiella burnetii (causative agent of Q fever) is an important zoonotic disease with a universal occurrence. Ticks are natural and potential reservoirs of this bacterium and play an effective role in the transmission of Q fever. This study aimed to investigate the prevalence of Coxiella burnetii in hard ticks isolated from livestock in Sistan. Subjects and Methods This cross-sectional study was conducted in five counties of the Sistan region. The genus and species of hard ticks were identified after collection from some domestic animals. The nested- PCR technique was used to identify the bacterial genome. Results Of all examined ticks, two genera, including 354 Hyalomma (59.399%) and 242 Rhipicephalus (40.6%) were identified. The hard ticks are in three types of species as follows: Rhipicephalus sanguineus (40.1%), Rhipicephalus nymph (0.5%), Hyalomma anatolicum (47.5%), Hyalomma sp. (1.5%), Hyalomma nymph (10.4%), and Rhipicephalus (Boophilus) annulatus (0.16%). No infected specimen with Coxiella burnetii was observed in the Sistan region. Conclusion According to the results of previous studies in Sistan and Baluchestan province and neighboring provinces that reported a high prevalence of Coxiella burnetii in collected ticks, it seems that more extensive research, with a larger sample size and host range, is necessary to clarify the situation of this pathogen.

Molecular Epidemiological Investigation of Piroplasms and Anaplasmataceae Bacteria in Egyptian Domestic Animals and Associated Ticks.

Piroplasmosis and anaplasmosis are serious tick-borne diseases (TBDs) that are concerning for the public and animal health. This study aimed to detect the molecular prevalence and epidemiological risk factors of Piroplasma and Anaplasma species in animal hosts and their associated ticks in Egypt. A total of 234 blood samples and 95 adult ticks were collected from animal hosts (112 cattle, 38 sheep, 28 goats, 26 buffaloes, 22 donkeys, and 8 horses) from six provinces of Egypt (AL-Faiyum, AL-Giza, Beni-Suef, Al-Minufia, Al-Beheira, and Matruh). Blood and tick samples were investigated by polymerase chain reaction coupled with sequencing targeting 18S and 16S RNA genes for Piroplasma and anaplasmataceae, respectively. Statistical analysis was conducted on the potential epidemiological factors. Of the 234 animals examined, 54 (23.08%) were positive for pathogens DNA distributed among the six provinces, where 10 (4.27%) were positive for Piroplasma, 44 (18.80%) for anaplasmataceae, and 5 (2.14%) were co-infected. Co-infections were observed only in cattle as Theileria annulata and Anaplasma marginale plus Babesia bigemina, A. marginale plus B. bigemina, and T. annulata plus B. bigemina. Piroplasmosis was recorded in cattle, with significant differences between their prevalence in their tick infestation factors. Animal species, age, and tick infestation were the potential risk factors for anaplasmosis. All ticks were free from piroplasms, but they revealed high prevalence rates of 72.63% (69/95) with anaplasmataceae. We identified T. annulata, B. bigemina, and A. marginale in cattle; A. platys in buffaloes; A. marginale and A. ovis in sheep; for the first time, A. ovis in goats; and Ehrlichia sp. in Rhipicephalus annulatus ticks. Our findings confirm the significant prevalence of piroplasmosis and anaplasmosis among subclinical and carrier animals in Egypt, highlighting the importance of the government developing policies to improve animal and public health security.

Potential of Marava arachidis, a Newly Recorded Earwig Species in Egypt as a Biological Control Agent of Rhipicephalus annulatus Tick in Laboratory.

Simple SummaryBased on both the morphological and molecular data of the earwig samples collected from a bakery in Beni-Suef, Egypt, we identified the species as Marava arachidis (Spongiphoridae). The predation capability of M. arachidis against the eggs and larvae (in-ground stages) of the Rhipicephalus annulatus tick under laboratory conditions was assessed. Laboratory findings revealed that this species has predation capability on R. annulatus tick eggs and larvae.In Egypt, only five species of Dermaptera (earwigs) have been reported. Based on both the morphological and molecular data of the earwig samples collected from a bakery in Beni-Suef, Egypt, we identified the species as Marava arachidis (Spongiphoridae), a cosmopolitan species with no prior records in Egypt. The current study was designed to analyze its predation capability on newly emerged eggs and larvae of the Rhipicephalus annulatus tick. A laboratory functional response study was set up by applying a predation test with various predator-prey ratios as treatments. This experiment was applied using the undefined mix of collected earwigs and the laboratory-collected eggs and the larvae of R. annulatus. The laboratory results showed that the mean number of predated tick eggs was 18.64 ± 11.18 in 24 h under the highest predator-prey ratio (1:10) examined, accompanied by 12.04 ± 4.38 broken but unconsumed eggs. Moreover, M. arachidis predated an average of 12.32 ± 9.07 tick larvae per day. In contrast, the mean dead larvae increased to 38.4 ± 2.30 per day with the highest predator density (1:10). The number of eggs and larvae consumed increased with the predator density. A linear relationship was detected between earwig density and the consumption rates of tick eggs (R2 = 0.99; p = 0.0001) and larvae (R2 = 0.96; p = 0.003). In conclusion, M. arachidis was first recorded in Egypt. This earwig has predation capability on R. annulatus tick eggs and larvae.

Role of antioxidant activity of essential oils in their acaricidal activities against Rhipicephalus annulatus.

Essential oils of Origanum majorana and Satureja thymbra as well as carvacrol are natural products that are known to have potent antioxidant activities. The current study was designed to investigate the role of the antioxidant properties of these natural products in their acaricidal activities against Rhipicephalus annulatus larvae. The synergistic and/or antagonistic effects of the addition of vitamins E and C and hydrogen peroxide (H2O2) to these natural products were also evaluated. Larval packet tests were used to evaluate the acaricidal activities against the larvae of R. annulatus. The antioxidant effectiveness of these products was determined by a DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical scavenging assay. The addition of vitamin E at 100mg/mL to O. majorana and S. thymbra decreased the concentrations required to achieve the death of half of the larvae (LC50) to 0.44 and 0.47%, respectively. The combination of O. majorana and S. thymbra attained the LC50 at 1.54% which was decreased to 0.69% after addition of vitamin E. Also, the addition of vitamin E to carvacrol reduced the LC50 to 0.27%. The total antioxidant activity of these natural products increased significantly in presence of vitamin E. The addition of H2O2 inhibited the acaricidal activity of all tested materials, especially at low concentrations. All treatments induced an increase in lipid peroxidation, whereas carvacrol-treated larvae revealed the lowest values for the superoxide dismutase. Glutathione peroxidase and catalase activity decreased in larvae treated with S. thymbra combined with vitamin E. In conclusion, the addition of vitamins E and C increased the acaricidal activities of the tested compounds, whereas the addition of H2O2 decreased these activities. The antioxidant activities of essential oils and their active components may play an important role in mediating their acaricidal activities.

Predicting the potential distribution of the cattle fever tick Rhipicephalus annulatus (Acari: Ixodidae) using ecological niche modeling.

Rhipicephalus annulatus is a tick species of veterinary importance due to its potential to transmit babesiosis to cattle. This species has a Holarctic distribution with some Afrotropical records and is one-host species of veterinary importance. This study was carried out from September 2021 to February 2022 at 6 Egyptian collection sites, and a total of 1150 cattle were scanned randomly to collect ticks. A total of 1095 tick specimens were collected and identified as R. annulatus using taxonomic keys. Males were found on all parts of the cattle except the head and around the eyes, but females were found on all parts; in addition, the highest number of specimens was gathered from the udder, (neck and chest), and belly. Maximum entropy (MaxEnt) modeling was used to predict the potential global distribution of R. annulatus. The MaxEnt model performed better than random with an average test area under the curve (AUC) value of 0.96, and model predictions were significantly better than random and gave (AUC) ratios above the null expectations in the partial receiver operating characteristic (pROC) analyses (P < 0.001). Based on correlation analyses, a set of 9 variables was selected for species from 15 bioclimatic and 5 normalized difference vegetation index (NDVI) variables. The study showed that the current distribution of R. annulatus is estimated to occur across Asia, Africa, Europe, South America, and North America. Annual mean temperature (Bio1) and median NDVI had the highest effect on the distribution of this species. The environmentally suitable habitat for R. annulatus sharply increased with increasing annual mean temperature (Bio1). These results can be used for making effective control planning decisions in areas suitable to this vector of many diseases worldwide.

Environmental factors driving fine-scale ixodid tick abundance patterns

Tick abundance is an essential demographic parameter to infer tick-borne pathogen transmission risks. Spatiotemporal patterns of tick abundance are heterogeneous, so its determinants at small spatial scales need to be understood to reduce their negative effects on hosts. Current knowledge of these determinants is scarce, especially in Mediterranean environments, limiting the possibilities for designing efficient tick control strategies. With the goal of unravelling tick abundance determinants and informing new tick management strategies, we estimated tick burdens on 1965 wild ungulates in Doñana National Park, Spain, annually between 2010 and 2020. Under the hypothesis of a predominant host influence on tick abundance, we modelled the burdens of Rhipicephalus annulatus, Hyalomma lusitanicum, and Ixodes ricinus with relevant predictors grouped into four factors: i) environment; ii) host population; iii) host individual; and iv) land-use. Generalized linear mixed models with a zero-inflated negative binomial distribution were built. Additionally, we analysed the differential contribution to abundance of each factor by deviance partitioning. We finally estimated the similarity in the environmental space of tick species by analysing their niche overlap with the environmental principal component analysis method. Our work hypothesis was confirmed for R. annulatus and H. lusitanicum, but we found that tick abundance at a fine spatial scale is jointly driven by multiple drivers, including all four factors considered in this study. This result points out that understanding the demography of ticks is a complex multifactorial issue, even at small spatial scales. We found no niche differences between the three tick species at the study spatial scale, thus showing similar host and environmental dependencies. Overall results identify that host aggregation areas displaying environmentally favourable traits for ticks are relevant tick and vector-borne pathogen transmission hotspots. Our findings will facilitate the design of new strategies to reduce the negative effects of tick parasitism.

Molecular detection of pathogens in the ova and unfed larvae of Rhipicephalus annulatus and Haemaphysalis bispinosa ticks infesting domestic cattle of south India

This study aimed to investigate the presence of pathogens in the engorged ticks infesting domestic cattle, their ova, and unfed larvae. The engorged female ticks infesting domestic cattle of Wayanad district of Kerala, south India were collected and kept for oviposition. The dead females after the complete oviposition, their egg masses, and unfed larvae were screened for the presence of various pathogens by specific PCRs. The presence of Babesia bigemina, Anaplasma marginale, A. phagocytophilum, and Rickettsia spp. similar to R. raoultii was confirmed in Rhipicephalus annulatus ticks, their egg masses, and unfed larvae. Theileria orientalis was detected in Rh. annulatus females, but not in their egg masses or progenies. The presence of A. phagocytophilum and Rickettsia spp. similar to R. raoultii was confirmed in Haemaphysalis bispinosa ticks, their egg masses, and unfed larvae too. The presence of coinfections of B. bigemina with A. phagocytophilum and A. marginale were detected in Rh. annulatus ticks and their progenies.