Cattle Tick Research Articles

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.

A Review of Australian Tick Vaccine Research.

Tick vaccine research in Australia has demonstrated leadership worldwide through the development of the first anti-tick vaccine in the 1990s. Australia’s Commonwealth Scientific and Industrial Research Organisation’s (CSIRO) research led to the development of vaccines and/or precursors of vaccines (such as crude extracts) for both the cattle tick and the paralysis tick. CSIRO commercialised the Bm86 vaccine in the early 1990s for Rhipicephalus australis; however, issues with dosing and lack of global conservation led to the market closure of Tick-GARD in Australia. New research programs arose both locally and globally. The Australian paralysis tick Ixodes holocyclus has perplexed research veterinarians since the 1920s; however, not until the 2000s did biotechnology exist to elucidate the neurotoxin—holocyclotoxin family of toxins leading to a proof of concept vaccine cocktail. This review revisits these discoveries and describes tributes to deceased tick vaccine protagonists in Australia, including Sir Clunies Ross, Dr Bernard Stone and Dr David Kemp.

Acaricidal Activity of Phenolic Crude Extract from Artocapus lakoocha Leaves against Cattle Tick Rhipicephalus (Boophilus) microplus

Cattle ticks and tick-borne diseases (TBDs) are well known for their harmful effects to cattle health. The problem of TBDs has been ranked high in terms of their adverse impact on the livelihood of poor farming communities in developing countries including Thailand. The aim of this research was to evaluate the efficacy of phenolic compounds of crude acetone extract and crude ethanol extract from Artocapus lakoocha leaves in the elimination of the cattle ticks which were tested in the form of crude extract at the concentration of 400, 800 and 1600μg/ml. From the record of mortality rate within 48 hours and propagation index within 15 days, it was found that the extract at the concentration of 1600μg/ml had the best efficacy to eliminate cattle ticks when compared to control group and other concentrations (P<0.05). It was also discovered that the mortality rate of ticks was 72%. Moreover, index of egg laying, and inhibition percentage were equal to 0.14 and 49, respectively. The negative control group adding with polyethylene glycol (PEG, Phenolic inhibitors) had mortality rate of cattle ticks at 0% and median of toxic concentration (Lethal Concentration 50: LC50) of phenolic crude extract was 1050μg/ml. Thus, the phenolic crude extract from Atrocapus lakoocha leaves was effective in getting rid of cattle ticks, this approach could be further developed as the effective method for controlling and eliminating ticks in the form of products such as shampoo and tick spray for cattle or other animals.

Characterization of a strain of Serratia sp. with ixodicide activity against the cattle tick Rhipicephalus microplus.

Cattle ticks are considered the most important ectoparasite in the livestock industry. Rhipicephalus microplus causes economic losses both through direct feeding on livestock and through disease transmission. Reports of the failure of chemical ixodicides to control this tick have led to a search for control alternatives, such as bacteria with ixodicide activity. The objective of this work was to select a bacterial strain with ixodicide activity against R. microplus. In total, 83 bacterial strains were isolated from soil and dead R. microplus specimens, and all strains were evaluated against larvae in a screening test. Bacteria with ixodicide activity were evaluated in larvae and engorged adult female ticks. The larvae were challenged using the larval immersion test (LIT) with 20µg/mL total protein. The median lethal concentration (LC50) for larvae was obtained by using nine total protein concentrations. Engorged adult female ticks were challenged using the adult immersion test (AIT) with six protein concentrations. We evaluated adult mortality on day 10, oviposition rate on day 14 and hatching rate on day 40 after challenge. Only one bacterial strain (EC-35) showed ixodicide activity against larvae and adult R. microplus. The highest larval mortality, 52.3%, occurred with a total protein concentration of 40μg/mL, and the LC50 was 13.9µg/mL of protein. In adults, a total protein concentration of 10µg/mL had the highest mortality (55%), oviposition inhibition (50.9%) and reproductive potential inhibition (52.5%). However, there was no significant effect on hatching. The 16S rRNA gene sequence showed 99% identity of EC-35 with Serratia sp.

Acaricidal activity of the hexanic and hydroethanolic extracts of three medicinal plants against southern cattle tick Rhipicephalus (Boophilus) microplus (Acari: Ixodidae).

The southern cattle tick Rhipicephalus microplus is a major problem for the cattle industry in tropical and subtropical areas worldwide. Chemical products are commonly applied to control it; however, their indiscriminate use has resulted in the appearance of resistant lineages. In the last decades, plants have been used as an alternative to conventional acaricidal drugs, as several plant compounds repel activity, decrease the reproductive potential and reduce the survival rate of ticks. For this reason, the in vitro efficacy of hexanic and hydroalcoholic extracts of Randia aculeata, Moringa oleifera and Carica papaya were evaluated against the larvae and engorged females of R. microplus. Larval packet tests and adult immersion tests were performed with seven concentrations of each of the extracts. The extracts obtained with hydroethanolic solution (polar solvent) exhibited a higher acaricidal activity than extracts prepared with n-hexane (non-polar solvent). Hydroethanolic extracts of R. aculeata seed and shell showed the highest larvicidal activity against R. microplus (100 and 91% mortality, respectively) at a concentration of 100mg/mL. Randia aculeata (seed and shell), M. oleifera and C. papaya treatments at the same concentration (100mg/mL) also resulted in adult mortality of 85, 75, 66 and 55%, respectively. The adult immersion test showed that hydroethanolic extracts derived from R. aculeata seed significantly reduced the index of egg laying and increased the percentage inhibition of oviposition of female ticks at a concentration of 100mg/mL. These results indicate that the tested extracts exhibit acaricidal activity and could be considered as potential agents for the development of alternative natural acaricides against R. microplus.

Assessing HeberFast® Line Gavac, a lateral flow immunochromatographic system for the rapid detection of anti-Bm86 antibodies in Gavac vaccinated cattle

Rhipicephalus Boophilus microplus cattle tick is a scourge for livestock production. The infestations produced by this pathogen are incompletely contained by chemical treatments, with the associated environmental pollution risks. Vaccination against cattle ticks has emerged as a feasible and environmentally friendly strategy to control tick-borne diseases. In this setting, Gavac® vaccine has proven effective in decreasing cattle tick populations through antibody responses against the tick Bm86 antigen, as part of an Integrated Control Program. However, animal vaccination programs require easy and ready-to-use screening tests to follow up the immune response in vaccinated animals under field conditions. This study reports the evaluation HeberFast® Line Gavac, a lateral flow immunochromatographic system for the rapid detection of anti Bm86 antibodies in vaccinated cattle. The system was tested on 598 serum samples taken from immunized animals, arranged in three groups according to their anti-Bm86 antibody response in ELISA (209 high, 150 medium or 239 low and 100 samples from non-immunized animals. The HeberFast® Line Gavac system was assessed for sensitivity, specificity, and concordance against the ELISA reference test. Consistency was evaluated among production batches and inter-analyst reading-independent consistency at two moments: ten minutes after completing the test and after strip drying. The system showed high sensitivity (81.6%, 82.2%, and 81%), specificity (96.7, 94.6, and 93.3%), and agreement with the ELISA reference test (75%; 74%, and 71%) for high, medium and low anti-Bm86 sera, respectively. The effectiveness of the diagnosis was 87.6; 87.1; 85.9 for high, medium, and low antibody titers, respectively. Consistency among production batches and analysts was documented, and no significant differences between evaluation times were found. These results indicate that HeberFast® Line Gavac is a valuable tool for the serological surveillance of Gavac vaccinated cattle.

Structural dynamics of Rhipicephalus microplus serpin-3

ABSTRACT Cattle ticks, Rhipicephalus (Boophilus) microplus, have a serious impact on livestock worldwide. For tick control, host vaccination is more sustainable than chemical. Salivary serpin (serine protease inhibitor) from R. microplus (RmS-3) is a potential anti-tick vaccine candidate antigen. Like other serpins, RmS-3 has a suicide inhibition mechanism, where the reactive centre loop (RCL) is cleaved and then inserted into the main β-pleated sheet. This causes the breakdown of serpin into two regions (core domain and cleaved polypeptide). A small sequence variation of RmS-3 was observed among specimens in Thailand included three extra amino acids (T147, K180, N193). Molecular Dynamics simulations of the previously reported (Micro) and the novel Thai RmS-3 (Thai) were conducted in comparison. Overall, Micro is more rigid than Thai. Having additional T147 and K180 enhance the structural flexibility in Thai. Both residues are located close to areas that perform a distinct conformational change, so T147 and K180 may impact inhibitory activity of Thai RmS-3. In contrast, N193 seems to have a minor effect. A presence of T147 and K180 in Thai seems to cause significant differences in structural dynamics which may lead to different degrees of inhibition activity. Further experimental studies are required.

TICK SALIVA TOXINS, HOST IMMUNE RESPONSES AND ITS BIOLOGICAL EFFECTS

Ticks are the most important ancient group of obligate blood-sucking ectoparasites of terrestrial vertebrates mainly of livestock. These small-sized animals are found in tropical and sub-tropical regions of the world. These act as vectors and transmit a wide range of protozoa, bacteria and viruses tick-borne diseases. These attach to host skin for blood-sucking and transmit disease pathogens through saliva. Ticks withdraw large volumes of blood from livestock and make them anemic and do significant weight loss. Ticks cause severe economic losses in livestock directly through blood-feeding and indirectly by transmitting protozoan, rickettsial and viral diseases This article highlights toxins/proteins secreted in tick saliva, and its important biological effects like anti-inflammatory, immunosuppressant peptide, and immunomodulatory and anti-chemokine activities. The present article clears host-pathogen interactions and invasion of a host by ticks, biological effects of tick saliva toxins and its host immune responses. These toxins could be used as immunoreactive proteins as a prerequisite for the development of specific and sensitive immunoassays for the determination of tick-borne illness. The authors suggest important management strategies for successful control of cattle, bird and canine ticks. This article also suggests tick control methods such as physical, chemical, hormonal and including prophylactic use of antibody and vaccine immune therapy.

Integrated control of the cattle tick, Rhipicephalus australis (Acari: Ixodidae), in New Caledonia through the Pasture and Cattle Management method.

Development of the Pasture and Cattle Management (PCM) method is a priority to control the cattle tick, Rhipicephalus australis, in New Caledonia. The PCM method provides the foundation for sustainable integrated tick control because approximately 95% of cattle ticks in infested pastures are off the host in the non-parasitic life stages, and the practice of treating cattle intensely with chemical acaricides is a risk for the emergence of resistance to these active ingredients in commercial acaricidal products available for veterinary use. Here, we report the findings of an assessment survey to document the utility of the PCM method. Analyses of questionnaire data provided by 21 beef cattle producers describing their management of 37 herds informed how to (1) assess the ability of PCM to reduce acaricide use and (2) prioritize best practices and define recommendations to breeders promoting efficient tick control with minimum acaricide use. Boosted regression tree analysis showed a significant (p = 0.002) reduction of ≈33% in the number of acaricide treatments from 7.9 to 5.3 per year by using PCM. Of the 24 factors identified as potentially affecting acaricide use, six factors accounted for ≈86% of the variability in number of acaricide treatments applied annually. The six most influential factors involved farm characteristics as well as pasture and herd management recommendations. These results demonstrated the usefulness of PCM for integrated control of R. australis infestations while reducing acaricide use to improve cattle production in New Caledonia.

Acaricidal activity and biochemical analysis of Citrus limetta seed oil for controlling Ixodid Tick Rhipicephalus microplus infesting cattle

The present study was performed with an objective to determine acaricidal activity of Citrus limetta seed oil (CLO) against cattle tick Rhipicephalus microplus. The mode of action of CLO was determined by evaluating biochemical enzymatic levels in treated ticks. CLO was obtained by extracting with n-hexane as solvent in soxhlet apparatus. The active compounds in CLO were analyzed through Gas chromatography. Acaricidal activity of CLO was evaluated using larval packet test (LPT) and adult immersion test (AIT). Results of chromatographic analysis showed that palmitic acid, stearic acid, α-Tocopherol and bergamol were present as major active constituents along with other compounds. The lethal concentration (LC50) of CLO was found to be 2.87% and 3.96% for larvae and adult of R. microplus ticks, respectively. In vitro acaricidal bioassay revealed 100% mortality of ticks in both LPT and AIT at 12.5% dose. CLO significantly (p < 0.001) reduced oviposition rate, hatching ability of eggs and reproduction efficiency of ticks. Biochemical analysis of ticks homogenate showed different enzymatic levels. The results revealed that CLO disturbed protective enzymes functions by reducing level of SOD, GST, MAO and AChE but increasing NOS level in ticks as compared with control group. Thus, CLO may be used as an effective acaricidal agent in controlling R. microplus ticks.

Allelic Variation in Protein Tyrosine Phosphatase Receptor Type-C in Cattle Influences Erythrocyte, Leukocyte and Humoral Responses to Infestation With the Cattle Tick Rhipicephalus australis.

The protein tyrosine phosphatase receptor type-C (PTPRC) gene encodes the common leukocyte antigen (CD45) receptor. CD45 affects cell adhesion, migration, cytokine signalling, cell development, and activation state. Four families of the gene have been identified in cattle: a taurine group (Family 1), two indicine groups (Families 2 and 4) and an African “taurindicine” group (Family 3). Host resistance in cattle to infestation with ticks is moderately heritable and primarily manifests as prevention of attachment and feeding by larvae. This study was conducted to describe the effects of PTPRC genotype on immune-response phenotypes in cattle that display a variable immune responsiveness to ticks. Thirty tick-naïve Santa-Gertrudis cattle (a stabilized composite of 5/8 taurine and 3/8 indicine) were artificially infested with ticks weekly for 13 weeks and ranked according to their tick counts. Blood samples were taken from control and tick-challenged cattle immediately before, then at 21 d after infestation and each subsequent week for 9 weeks. Assays included erythrocyte profiles, white blood cell counts, the percentage of cellular subsets comprising the peripheral blood mononuclear cell (PBMC) population, and the ability of PBMC to recognize and proliferate in response to stimulation with tick antigens in vitro. The cattle were PTPRC genotyped using a RFLP assay that differentiated Family 1 and 3 together (220 bp), from Family 2 (462 bp), and from Family 4 (486 bp). The PTPRC allele frequencies were Family 1/3 = 0.34; Family 2 = 0.47; Family 4 = 0.19. There was no significant association between PTPRC genotype and tick count. Each copy of the Family 1/3 allele significantly decreased total leucocyte count (WCC) and CD8+ cells. Increasing dosage of Family 2 alleles significantly increased red blood cell count (RCC), haematocrit (PCV), and haemoglobin (Hb) concentration in blood. Increasing dosage of the Family 4 allele was associated with increased WCC, reduced RCC, reduced PCV and reduced Hb. Homozygote Family 1/3 animals had consistently lower IgG1 in response to tick Ag than homozygote Family 2 animals. The PTPRC genotype influences the bovine immune response to ticks but was not associated with the observed variation in resistance to tick infestation in this study.

Acaricidal activity and clinical safety of arecoline hydrobromide on calves infested with cattle tick Rhipicephalus microplus (Acari: Ixodidae)

The objective of the present study was to determine the acaricidal activity of arecoline hydrobromide against cattle tick Rhipicephalus microplus infesting calves. in vivo efficacy of arecoline emulsified with polysorbate-80 (2%) was evaluated using ear bag method with the effective dose of 12.5 mg/mL applied on ear pinna of calves infested with ticks. Control group received polysorbate-80 (2%) after larvae infestation, however, reference group received deltamethrin (0.5 %). The experiment was continued for six days (144 h) and treatment of drug was given twice a day. Daily observation of calves was done to count the number of ticks after treatment. Acute dermal toxicity study for test drug was performed on wistar rats. Clinical safety of arecoline was determined by examining hematological profile and skin irritancy assay for calves infested with ticks. Results showed that arecoline significantly (p < 0.01) reduced the number of ticks attached to ear pinna of calves. Fewer number of ticks remained on calves skin at 120 h and 144 h were 8.09 and 6.21, respectively after treatment with arecoline in comparison to control group. Treatment of animals with arecoline hydrobromide significantly (p < 0.01) restored the hematological profile of animals as hemoglobin (Hb) level was 9.01 g/100 mL, PVC was 29.24 %, TEC and TLC were 5.23 and 7.19 106/cumm, respectively as compared to the control group having Hb 9.48 g/100 mL, PVC 31.60 %, TEC 5.64 106/cumm and TLC 7.27 106/cumm. Arecoline showed no toxicity while applied on wistar rats. The drug was mild irritative for an initial 20 min to the calves after that no redness or erythema was seen on the skin of the animals. Thus, arecoline hydrobromide may be an effective alternative to be used as herbal ectoparasiticide for the eradication of R. microplus ticks.

Efficacy of two commercial synthetic pyrethroids (cypermethrin and deltamethrin) on Amblyomma variegatum and Rhipicephalus microplus strains of the south-western region of Burkina Faso

Since 2011, period of the livestock invasion by the cattle tick Rhipicephalus microplus in Burkina Faso (BF), tick-control problems were exacerbated. Based on farmer’s reports, most commonly used commercial acaricides were found to be ineffective in Western South part of the country. To investigate the occurrence and extent of such acaricidal ineffectiveness, we performed the standardized larval packet test (LPT) with commercial deltamethrin (vectocid) and cypermethrin (cypertop), on two cattle tick species, the native Amblyomma variegatum and the invasive R. microplus. The resistance ratios (RR) were computed with susceptible Hounde strain of Rhipicephalus geigyi as reference. The R. microplus population showed resistance to the two acaricides tested with the highest lethal concentration (LC) values, and different resistance ratios higher than 4 (deltamethrin: RR50 = 28.18 and RR90 = 32.41; cypermethrin: RR50 = 8.79 and RR90 = 23.15). In the contrary, A. variegatum population was found to be highly susceptible to acaricides tested with low lethal concentrations and resistance ratio values (deltamethrin: RR50 = 0.5 and RR90 = 0.48; cypermethrin: RR50 = 0.68 and RR90 = 0.79). These data demonstrate high synthetic pyrethroid resistance in R. microplus strain, leading to conclude that the acaricide ineffectiveness in tick populations control remains a concern in BF.

Effect of integrated technology for fattening beef cattle in the livestock zone of North Sulawesi

This on-farm study aims to increase beef cattle productivity by utilizing integrated technology packages for local cattle fattening with a target of at least 800g/head daily gain. This study was carried out in the Minahasa Selatan district from August to October 2018. The integrated technology package for the fattening business pattern included: (1) complete feed, (2) intensive maintenance in multi-purpose cages, and (3) eradication of complete parasites. A complete feed is formulated in a balanced feed consisting of ammoniated rice straw and concentrate locally. The amount of dry matter concentrate was given per head is 1.5% of body weight (50% total consumption), while the ammoniated straw was ad libitum. For multipurpose cages, the upper part is equipped with a multipurpose tower as a barn while simultaneously serving straw, ad libitum, and continuous. Complete eradication of parasites using broad-spectrum anti-parasites to eradicate endoparasites that attack digestive tissues and other internal organs and ectoparasites to control the skin worms and eyeworms, cattle grubs, mange mites, sucking lice, sand tampans, and ticks. This study used fifteen local PO bulls fattened with an initial body weight of an average of 278.4 kg (± 54.34) with an observation period of 12 weeks. The observations showed that the average daily gain was 1,158 g/head, feed consumption 8,358 kg DM/head/day, and feed conversion ratio of 7.56. In contrast, the results of the business feasibility analysis showed a BCR coefficient of 1.69. The results of statistical analysis showed that the average weight gain increased significantly (p <0.01) after utilizing integrated fattening technology (308.8vs278.4 kg). It was concluded that the use of integrated technology for cattle fattening in beef cattle could increase productivity significantly and economically feasible.

Molecular survey and phylogenetic analysis of tick-borne pathogens in ticks infesting cattle from two South Indian states.

In this study, the molecular survey of cattle ticks and tick-borne pathogens in various agroclimatic zones in Karnataka and Kerala states, India, and phylogenetic analysis of gene sequences were accomplished. Overall, 240 pooled tick DNA samples from two states were used for the identification of three tick genera and nine tick-borne pathogens by using the PCR method and sequencing. The distribution of Haemaphysalis (Ha.), Hyalomma (Hy.), and Rhipicephalus (R.) species were 5.0, 17.5, and 65.8% in Karnataka and 5.8, 11.7, and 65.0% in Kerala, respectively. The prevalence of Anaplasma marginale, Babesia bovis, Rickettsia species, and Trypanosoma evansi was 8.3, 0.8, 6.7, and 0.0% in Karnataka and 14.2, 0.0, 8.3, and 8.3% in Kerala, respectively. The pooled tick DNA samples were negative for Bartonella species, Borrelia species, Coxiella burnetti, Pasteurella multocida, and Theileria species. The season-wise analysis revealed a high occurrence of Ha. species in all seasons except for post-monsoon, Hy. and Rhipicephalus species in monsoon season in Karnataka, and all three tick genera were present in monsoon season in Kerala. The sequence analysis of mitochondrial cytochrome oxidase subunit 1 gene facilitated the identification of tick species namely, Ha. bispinosa, Ha. japonica, Hy. excavatum, R. annulatus, R. decoloratus, R. microplus, and R. sanguineus. The Rhipicephalus species was a major tick in these two states, and Rickettsia endosymbiont and Trypanosoma evansi in tick were detected in this study. This study represents the first report about the presence of Rickettsia massiliae in Ha. bispinosa in Karnataka and Trypanosoma evansi in R. species in Kerala. Phylogenetic analysis revealed sequence homology between the different isolates from India and neighbouring countries. Thus, the study provides key information on the distribution of ticks and tick-borne pathogens of cattle in Karnataka and Kerala, which will aid in developing and strategizing effective control measures.

First report on efficacy of Citrus limetta seed oil in controlling cattle tick Rhipicephalus microplus in red Sahiwal calves

The objective of the study was to evaluate the acaricidal activity of Citrus limetta seed oil (CLO) for controlling the cattle tick Rhipicephalus microplus. C. limetta seeds were collected as a waste product from different juice corners. CLO was obtained after extraction of seeds on soxhlet apparatus using n-hexane as solvent. It was characterized through Gas Chromatography-High Resolution Mass Spectroscopy (GC-HRMS) to determine the presence of active constituents. In vitro bioassays were performed using adult immersion test (AIT) and larval packet test (LPT). In vivo acaricidal efficacy of CLO was performed on red Sahiwal calves using ear bag method. Clinical safety of CLO was evaluated by observing haematological parameters and skin irritancy assay. Results of GC-HRMS showed that mainly fatty acids such as linoleic acid, stearic acid, oleic acid, palmitic acid, and linolenic acid were present in the CLO. CLO in the concentration of 125 mg/mL (CLO8) exhibited 100 % mortality in both AIT and LPT. CLO significantly (p < 0.001) reduced the number of ticks from 35 to 5.05 and 3.24 on 144 h after treatment with CLO7 and CLO8, respectively. CLO was found clinically safe without producing erythema and edema on skin. Haematological parameters such as haemoglobin (11.48 g/100 mL), total leucocytes count (4.32 106/cumm), total erythrocytes count (6.80 106/cumm), and packed cell volume (34.39 %) were normal and controlled. CLO may be used as effective and safe drug therapy for controlling R. microplus ticks.

Rhipicephalus microplus and Amblyomma sculptum (Ixodidae) infestation of Nellore cattle (Bos taurus indicus) in a farm of the Brazilian Cerrado: seasonality and infestation patterns.

We herein describe zebuine cattle tick infestation in a farm in southeast Brazil with an examination accurate enough to detect tick immatures and species other than R. microplus. Cattle were inspected monthly for ticks from May 2015 to May 2017 and 7604 ticks were collected along 276 bovine inspections. Rhipicephalus microplus was the dominant species (7197 specimens, 94.5% from the total), but Amblyomma sculptum was also collected (407/5.5%). Horse tick infestations were evaluated for comparison purposes of A. sculptum infestations of a primary host sharing pastures with bovines. Ticks were counted on the left side of 4-12 horses every 3months from October 2015 to October 2017. Overall, 68 horse inspections were performed and 1702 ticks were collected: Dermacentor nitens (805 specimens/47.3% of the total), A. sculptum (733/43.1%) and R. microplus (164/9.6%). Overall mean tick abundance on bovines was low if compared to that of taurine cattle and counting revealed four annual generations of R. microplus. The interval between infestation peaks was 3months, irrespective of the season, and an increase in tick counts from spring onward, as described in the south of Brazil, was not seen. Amblyomma sculptum infestation abundance was minor but constant and in high prevalence. Cattle infestation with A. sculptum seems to depend on pasture sharing with other domestic and wild hosts that are its primary hosts and provide engorged females to complete their life cycle. The impact of such tick sharing among several host species on tick-borne pathogen transmission remains to be elucidated.

In vitro evaluation of the acaricidal activity of propolis against cattle ticks

Propolis is a natural substance that is produced by bees and has been used since ancient times for its pharmacological properties. The cattle tick Rhipicephalus (Boophilus) microplusis responsible for great economic losses by cattle breeding programs. The aim of the present study was to evaluate the in vitro effect of propolis extracts on engorged female ticks. The experiment was performed at the Uberaba IFTM. A completely randomized experimental design was used, including eight treatments and five replicates, with a total 40 experimental units, each consisting of 10 engorged females of homogeneous weight. The experimental units were immersed in alcoholic propolis extracts that were diluted with distilled water to the following concentrations: 0, 10, 20, 30, 40, 50, 60, and 70%. A regression analysis was used to analyze the relationship between propolis extract concentration and weight of eggs laid (WEL), hatching percentage (HP), and reproductive efficiency (RE). This demonstrates the viability of propolis as an alternative for the control of cattle ticks, with the 70% extract concentration being most efficientand most effective for controlling R. microplus under laboratory conditions.

An integrated overview of the bacterial flora composition of Hyalomma anatolicum, the main vector of CCHF.

The microbial flora associated with Hyalomma anatolicum ticks was investigated using culture-dependent (CD) and independent (next generation sequencing, NGS) methods. The bacterial profiles of different organs, development stages, sexes, and of host cattle skins were analyzed using the CD method. The egg and female gut microbiota were investigated using NGS. Fourteen distinct bacterial strains were identified using the CD method, of which Bacillus subtilis predominated in eggs, larval guts and in adult female and male guts, suggesting probable transovarial transmission. Bacillus velezensis and B. subtilis were identified in cattle skin and tick samples, suggesting that skin is the origin of tick bacteria. H.anatolicum males harbour lower bacterial diversity and composition than females. The NGS analysis revealed five different bacterial phyla across all samples, Proteobacteria contributing to >95% of the bacteria. In all, 56611sequences were generated representing 6,023 OTUs per female gut and 421 OTUs per egg. Francisellaceae family and Francisella make up the vast majority of the OTUs. Our findings are consistent with interference between Francisella and Rickettsia. The CD method identified bacteria, such B. subtilis that are candidates for vector control intervention approaches such paratransgenesis whereas NGS revealed high Francisella spp. prevalence, indicating that integrated methods are more accurate to characterize microbial community and diversity.

The deletion of chiMaD1, a horizontally acquired chitinase of Metarhizium anisopliae, led to higher virulence towards the cattle tick (Rhipicephalus microplus).

The first line of the Arthropods defense against infections is the hard-structured exoskeleton, a physical barrier, usually rich in insoluble chitin. For entomopathogenic fungi that actively penetrate the host body, an arsenal of hydrolytic enzymes (as chitinases and N-acetylglucosaminidases), that break down chitin, is essential. Notably, twenty-one putative chitinase genes have been identified in the genome of Metarhizium anisopliae, a generalist entomopathogenic fungus. As a multigenic family, with enzymes that, presumably, perform redundant functions, the main goal is to understand the singularity of each one of such genes and to discover their precise role in the fungal life cycle. Specially chitinases that can act as virulence determinants are of interest since these enzymes can lead to more efficient biocontrol agents. Here we explored a horizontally acquired chitinase from M. anisopliae, named chiMaD1. The deletion of this gene did not lead to phenotypic alterations or diminished supernatant's chitinolytic activity. Surprisingly, chiMaD1 deletion enhanced M. anisopliae virulence to the cattle tick (Rhipicephalus microplus) larvae and engorged females, while did not alter the virulence to the mealworm larvae (Tenebrio molitor). These results add up to recent reports of deleted genes that enhanced entomopathogenic virulence, showing the complexity of host-pathogen interactions.