Tick Rhipicephalus Microplus Research Articles

Field efficacy of Metarhizium anisopliae oil formulations against Rhipicephalus microplus ticks using a cattle spray race

Rhipicephalus microplus tick is the main ectoparasite of cattle in Brazil. The exhaustive use of chemical acaricides to control this tick has favored the selection of resistant tick populations. Entomopathogenic fungi, as Metarhizium anisopliae, has been described as a potential biocontroller of ticks. Therefore, the aim of this study was to evaluate the in vivo efficacy of two oil based formulations of M. anisopliae for the control of the cattle tick R. microplus under field conditions using a cattle spray race as a method of treatment. Initially, in vitro assays were carried out with an aqueous suspension of M. anisopliae, using mineral oil and/or silicon oil. A potential synergism between oils and fungus conidia for tick control was demonstrated. Additionally, the usefulness of silicon oil in order to reduce mineral oil concentration, while improving formulation efficacy was illustrated. Based on the in vitro results, two formulations were selected for use in the field trial: MaO1 (107 conidia/mL plus 5% mineral oil) and MaO2 (107 conidia/mL plus 2.5% mineral oil and 0.01% silicon oil). The adjuvants concentrations (mineral and silicon oils) were chosen since preliminary data indicate that higher concentrations caused significant mortality in adult ticks. For this, 30 naturally infested heifers were divided into three groups based on previous tick counts. The control group did not receive treatment. The selected formulations were applied on animals using a cattle spray race. Subsequently, tick load was evaluated weekly by counting. The MaO1 treatment significantly reduced the tick count only on day +21, reaching approximately 55% efficacy. On the other hand, MaO2 showed significantly lower tick counts on days +7, +14, and +21 after treatment, with weekly efficacy achieving 66%. The results showed a substantial reduction of tick infestation, up to day +28, using a novel formulation of M. anisopliae based in the mixture of two oils. Moreover, we have shown, for the first time, the feasibility of employing formulations of M. anisopliae for large-scale treatment methods, such as a cattle spray race, which in turn, may increase the use and adhesion to biological control tools among farmers.

Molecular detection and genetic characterization of bovine hepacivirus identified in ticks collected from cattle in Harbin, northeastern China.

Bovine hepacivirus (BovHepV) is a member of the genus Hepacivirus of the family Flaviviridae, which can cause acute or persistent infections in cattle. Currently, BovHepV strains identified in cattle populations worldwide can be classified into two genotypes with eight subtypes in genotype 1. BovHepV has been identified in a wide geographic area in China. Interestingly, the viral RNA of BovHepV has also been detected in ticks in Guangdong province, China. In this study, Rhipicephalus microplus tick samples were collected in Heilongjiang province, northeastern China, and BovHepV was screened with an overall positive rate of 10.9%. Sequence comparison and phylogenetic analysis showed that the BovHepV strains detected in this study belong to the subtype G. This is the first report about the detection of BovHepV in ticks in Heilongjiang province, China, which expands our knowledge that ticks may be a transmission vector of BovHepV.

Potential of Tetradenia riparia leaf essential oil and its fractions in controlling Aedes aegypti and Rhipicephalus microplus larvae

Tetradenia riparia (Hochst.) Codd (Lamiaceae) is a shrub, commonly known as ginger bush or false myrrh, and several studies have shown that T. riparia exhibits a variety of biological properties. This study aimed to determine the chemical composition of T. riparia essential oil and its fractions, investigate their anticholinesterase activity, and assess their larvicidal activity against the cattle tick Rhipicephalus microplus and the mosquito Aedes aegypti. Eleven essential oil fractions were obtained by fractionation and analyzed by gas chromatography/mass spectrometry. Larvicidal activity against R. microplus and third-instar A. aegypti was assessed using a larval packet test and a larval immersion test, respectively. Anticholinesterase activity was determined by a bioautographic method. Forty-nine compounds were identified in the essential oil, of which the major classes were oxygenated sesquiterpenes (45.95%) and sesquiterpene hydrocarbons (35.20%) and the major components were isospathulenol (17.40%), β-caryophyllene (15.61%), 14-hydroxy-9-epi-caryophyllene (10.07%), 14-hydroxy-α-muurolene (8.32%), and 9β,13β-epoxy-7-abietene (5.53%). Bioassays showed that T. riparia essential oil (LC50 = 1.56 µg/mL) and FR3 (LC50 = 0.30 µg/mL) were the most active against R. microplus and A. aegypti larvae, respectively. The essential oil and FR1, FR2, and FR3 exhibited acetylcholinesterase inhibitory activity. These results indicate that T. riparia essential oil and its fractions hold promise in the development of novel, environmentally safe agents for the control of R. microplus and A. aegypti larvae.

Assessment of Repellency and Acaricidal Potential of Nigella sativa Essential Oil Using Rhipicephalus microplus Ticks

Assessment of Repellency and Acaricidal Potential of Nigella sativa Essential Oil Using Rhipicephalus microplus Ticks

A comparison of two in vitro bioassays to detect resistance of the cattle tick Rhipicephalus microplus to fipronil.

The aim of this work is to compare the sensitivity of two in vitro bioassays to detect resistant to fipronil in Argentinean populations of the cattle tick Rhipicephalus microplus. Two different larval bioassays prepared with technical grade (97%) fipronil were compared: larval immersion test (LIT) and larval packet test (LPT). Seven strains from different provinces were treated with both assays. Colonia Tabay, Colonia Benítez, Intiyaco and Quimili strains were considered resistant in both LIT and LPT bioassays. The 95% confidence intervals (IC95) for lethal concentration 50% (LC50) did not overlap with the susceptible reference strain (SRS) and all the values of RR50 obtained were higher than 2. Garabato and Federal strains were considered as susceptible for both techniques because the IC95 for the LC50 overlapped with those of the SRS and the RR50 values were lesser than 2. An ambiguous situation occurs with Reconquista strain. This strain was considered as susceptible with LPT and with incipient resistant after LIT trial. The analysis of the results indicates that both LIT and LPT trials have enough sensibility to differentiate resistant and susceptible strains, but LIT was more sensitive than LPT when the resistance is incipient.

Expression and Purification of Recombinant Multi-epitope Protein of Rhipicephalus microplus Tick and its Antigenicity in Rabbits

Expression and Purification of Recombinant Multi-epitope Protein of Rhipicephalus microplus Tick and its Antigenicity in Rabbits

Characterization and evaluation of extracellular vesicles as anti-tick vaccine candidates

Among all the agricultural sectors, the livestock industry is the most economically developed and prolific. Livestock production promotes economic stability globally and provides a significant source of protein in meat and milk. Ticks can transmit pathogens such as Anaplasma marginale, the causative agent of Bovine Anaplasmosis, affecting the cattle industry due to mortality, reduction of meat and milk production, and increased costs for treatment and prevention. Bovine Anaplasmosis results in estimated losses of over 300 million USD per year in the U.S. There are no effective treatments since they act as bacteriostatic antimicrobials, arresting bacterial growth, but do not eliminate them. In subclinical levels the infection can persist. Further, the ability of A. marginale to undergo antigenic variation hinders vaccine development. Therefore, alternatives that target transmission and early establishment of the pathogen are needed. Extracellular vesicles are small membrane blebs secreted by eukaryotic cells that act in cell-to-cell communication. These vesicles can be divided into exosomes and microvesicles, depending on their mechanism of biogenesis and secretion. Recent studies, and my preliminary data, have shown that tick extracellular vesicles carry proteomic material that is conserved among different tick species. This proteomic material can be used as a vaccine candidate for the development of anti-tick vaccines. We hypothesize that these vesicles have potential as vaccine candidates for tick control. To test this hypothesis, we will: 1) Characterize the vesicle populations secreted by Dermacentor andersoni, Amblyomma americanum, and Rhipicephalus microplus ticks, 2) Define the best adjuvant-vesicle combination to trigger strong humoral and cellular responses in cattle, and 3) Determine the effectiveness of extracellular vesicle-derived vaccines for the management of tick populations in semi-field conditions. The emergence of acaricidal resistance in tick populations increases the need to develop new alternative control methods. Current vaccines have shown to be protective only against particular tick populations and species, for this reason artificial vesicles containing conserved proteins among different tick species, present a tempting approach that can be mass-produced and commercialized as an anti-tick vaccine protective against different tick species but specially R. microplus. This technology can be applied to other systems and would have a great impact in animal and human health.

Low Genetic Polymorphism in the Immunogenic Sequences of Rhipicephalus microplus Clade C.

Rhipicephalus microplus tick highly affects the veterinary sector throughout the world. Different tick control methods have been adopted, and the identification of tick-derived highly immunogenic sequences for the development of an anti-tick vaccine has emerged as a successful alternate. This study aimed to characterize immunogenic sequences from R. microplus ticks prevalent in Pakistan. Ticks collected in the field were morphologically identified and subjected to DNA and RNA extraction. Ticks were molecularly identified based on the partial mitochondrial cytochrome C oxidase subunit (cox) sequence and screened for piroplasms (Theileria/Babesia spp.), Rickettsia spp., and Anaplasma spp. PCR-based pathogens-free R. microplus-derived cDNA was used for the amplification of full-length cysteine protease inhibitor (cystatin 2b), cathepsin L-like cysteine proteinase (cathepsin-L), glutathione S-transferase (GST), ferritin 1, 60S acidic ribosomal protein (P0), aquaporin 2, ATAQ, and R. microplus 05 antigen (Rm05Uy) coding sequences. The cox sequence revealed 100% identity with the nucleotide sequences of Pakistan's formerly reported R. microplus, and full-length immunogenic sequences revealed maximum identities to the most similar sequences reported from India, China, Cuba, USA, Brazil, Egypt, Mexico, Israel, and Uruguay. Low nonsynonymous polymorphisms were observed in ATAQ (1.5%), cathepsin-L (0.6%), and aquaporin 2 (0.4%) sequences compared to the homologous sequences from Mexico, India, and the USA, respectively. Based on the cox sequence, R. microplus was phylogenetically assembled in clade C, which includes R. microplus from Pakistan, Myanmar, Malaysia, Thailand, Bangladesh, and India. In the phylogenetic trees, the cystatin 2b, cathepsin-L, ferritin 1, and aquaporin 2 sequences were clustered with the most similar available sequences of R. microplus, P0 with R. microplus, R. sanguineus and R. haemaphysaloides, and GST, ATAQ, and Rm05Uy with R. microplus and R. annulatus. This is the first report on the molecular characterization of clade C R. microplus-derived immunogenic sequences.

Resistance to Cypermethrin Is Widespread in Cattle Ticks (Rhipicephalus microplus) in the Province of Punjab, Pakistan: In Vitro Diagnosis of Acaricide Resistance.

Control of the cattle tick Rhipicephalus (R.) microplus mainly relies on chemical acaricides and cypermethrin is the most widely used acaricide in Pakistan. Farmers frequently complain about its low efficacy, thus, the present study was designed to quantify the frequency of cypermethrin resistance in cattle ticks. Engorged female R. microplus were collected and tested for the efficacy of cypermethrin using the FAO-recommended larval packet test. Resistance factors (RF) were estimated at both the lethal concentration for 50% (LC50) and 99% (LC99) of ticks. Thirty-three samples were tested, of which 8/33 (24.24%) were classified as resistant based on the RF50, and all 33 were classified as resistant based on the RF99. In District Sargodha, when only the RF50 was considered, 45.5% of samples were classified as resistant, but at RF99, all tested samples were identified as resistant. In District Okara, the variation in RF50 estimates was 2.2-8.3 and variation in RF99 estimates was 10.6-1139.8. Similar results were found in District Attock, where variations in RF50 were 0.8-8.5 and RF99 ranged from 9-237.3. The study showed that cypermethrin resistance is prevalent in these three districts of Pakistan and is likely to be overestimated by classification based on the RF99.

Seasonal fluctuations of Babesia bigemina and Rhipicephalus microplus in Brangus and Nellore cattle reared in the Cerrado biome, Brazil

BackgroundThe tick Rhipicephalus microplus (Ixodida: Ixodidae, Canestrini, 1888) causes substantial economic and health losses in cattle production and is the main vector of Babesia bigemina (Piroplasmidae: Babesidae, Smith & Kilborne, 1893). Babesia bigemina is responsible for a tick-borne disease known as babesiosis that can cause hemolytic anemia, fever and death. In the study reported here, we investigated the relationship between the number of ticks per animal and the number of B. bigemina cytochrome b gene (cbisg) copies in the blood of Brangus and Nellore cattle reared without acaricidal treatment in the Brazilian Cerrado biome over a 1-year period.MethodsTicks on 19 animals (9 Brangus and 10 Nellore cattle) were counted every 18 days, and blood was collected every 36 days for 12 months. Serological samples were analyzed with an indirect enzyme-linked immunosorbent assay, and genomic DNA was analyzed by conventional PCR and quantitative PCR. The PCR products were sequenced by the Sanger method.ResultsThe Brangus and Nellore breeds showed similar weight development and no clinical signs of babesiosis. Statistically significant differences (P < 0.05) between the breeds were observed for the number of ticks and the number of B. bigemina cbisg gene copies.ConclusionsNo correlation between the number of ticks and the number of circulating copies of cbisg was observed, although Nellore cattle presented with fewer ticks than Brangus cattle and the number of cbisg copies was higher for Nellore cattle than for Brangus cattle.

First Description of Acaricide Resistance in Populations of Rhipicephalus microplus Tick from the Lower Amazon, Brazil.

There is limited information on the resistance to acaricidal drugs of the cattle tick Rhipicephalus microplus in the Lower Amazon region. Thus, we aimed to determine the efficiency of three widely used acaricide products (Amitraz, Cypermethrin, and Deltamethrin) in the control of this tick species. The adult immersion test was used on engorged female ticks sampled on farms in the Lower Amazon region, Brazil. For the test, homogeneous batches of 10 engorged females were placed in Petri dishes and immersed in the tested acaricidal drugs, using four replicates of each acaricide and three replicates as a negative control, immersed in distilled water. The acaricides were diluted as recommended by the manufacturers, and the ticks were submerged for five minutes. Mortality of engorged females, production of eggs, and percentage of larval hatching were evaluated. Tick mortality was 2.5%, 7.5%, and 0% for Amitraz, Cypermethrin, and Deltamethrin, respectively. The percentage of larval hatching was 53.7% for Amitraz, 88.7% for Cypermethrin, and 80.0% for Deltamethrin. As recommended by the FAO, for the acaricide to be considered effective, it must have a control rate ≥95%. Among the tested acaricides, Amitraz showed an efficacy of 90.5%, Cypermethrin 10.4%, and Deltamethrin 26.6%. Ticks from the lower Amazon showed marked resistance to Cypermethrin and Deltamethrin and mild resistance to Amitraz. This is the first report of acaricidal resistance in the region.

Histometric and morphological damage caused by Serratia marcescens to the tick Rhipicephalus microplus (Acari: Ixodidae).

Rhipicephalus microplus tick is the ectoparasite causing the greatest economic losses in the livestock industry. Multi-resistance in ticks is increasing, generating the inefficiency of traditional ixodicides, for which biological control has been proposed as an alternative. In this work, we analyze the histomorphological damage caused by the bacterial strain EC-35 on Rhipicephalus microplus. The ixodicidal effect of EC-35 total protein was evaluated on larval or adult ticks comparing with the commercial ixodicide coumaphos 0.02% as a control. Female ticks were processed using the paraffin-embedding technique and stained with hematoxylin-eosin. Also, the pathogenicity of EC-35 was evaluated by capillary feeding and coelom inoculation tests. The identification of the bacterium was performed using the molecular markers 16S RNA and rpoB, by PCR and sequencing technique, and the evolutionary distance was analyzed by Bayesian phylogenetic inference. No differences were observed in the perimeter and area of larvae treated with EC-35 or Coumaphos. The thickness of the integument decreased a 65% with the EC-35 treatment (6.01 ± 0.6µm) and of 30% in coumaphos (12.04 ± 1.2µm) in larvae compared with the control group (18.41 ± 2µm), while no difference was found in adult ticks. The capillary feeding test and coelom inoculation with EC-35 showed an inhibition of reproductive potential of 99.8 ± 7 and an oviposition Inhibition 97 ± 3.02%. The EC-35 strain was genetically related to Serratia marcescens, concluding that these bacteria caused high mortality, oviposition Inhibition, and integument thinning and drastic loss of histoarchitecture in R. microplus tick larvae.

Interaction between anti-tick vaccine and a macrocyclic lactone improves acaricidal efficacy against Rhipicephalus (Boophilus) microplus (Canestrini) (Acari: Ixodidae) in experimentally infested cattle

The southern cattle fever tick (SCFT) Rhipicephalus (Boophilus) microplus, is considered the most important ectoparasite of livestock in the world because of high financial losses associated with direct feeding and transmission of the hemoparasites Babesia bovis, B. bigemina, and Anaplasma marginale. Unfortunately, SCFT in many parts of the world have evolved resistance to all market-available pesticides thus driving development of new control technologies. Vaccination against ticks using the tick gut protein Bm86 has been shown to be effective against acaricide-resistant ticks. This technique has been successfully implemented in Puerto Rico for the control of acaricide-resistant R. microplus on dairy and beef cattle. Observations from Puerto Rico indicate a potentially positive interaction between anti-tick vaccination when used in conjunction with systemic acaricide treatment. In this project, controlled animal studies were completed directly comparing efficacy of anti-tick vaccination with and without systemic acaricide. Results show that the Bm86 anti-tick vaccine in combination with the macrocyclic lactone, Moxidectin, expressed a synergistic interaction, providing greater and longer efficacy than either treatment alone.

One Health Approach to Identify Research Needs on Rhipicephalus microplus Ticks in the Americas.

We aim to provide a harmonized view of the factors that affect the survival and promote the spread of R. microplus in the Neotropics, approaching its different facets of biology, ecology, distribution, and control. We review the interactions among environmental niche, landscape fragmentation, vegetal coverage (abiotic traits), and the biotic aspects of its ecology (abundance of domesticated or wild competent hosts), proposing emerging areas of research. We emphasize a holistic view integrating an economically and ecologically sustainable control of infestations and transmitted pathogens by R. microplus in the Neotropics. Examples of research link the trends of climate, the composition of the community of hosts, the landscape features, and a tailored management based on ecological grounds. Our view is that factors driving the spread of R. microplus are complex and deeply interrelated, something that has been seldom considered in control strategies. The effects of climate may affect the dynamics of wildlife or the landscape composition, promoting new patterns of seasonal activity of the tick, or its spread into currently free areas. In this paper we encourage a One Health approach highlighting the main aspects governing the components of the tick’s life cycle and its interactions with livestock and wild animals.

Detection of Tick-Borne Pathogens in Ticks from Cattle in Western Highlands of Cameroon.

This study aimed to detect and identify microorganisms in ticks collected in the Western Highlands of Cameroon. Quantitative real-time and standard PCR assays, coupled with sequencing, were used. A total of 944 ticks collected from cattle in five distinct sites in Cameroon were selected for the analyses. They belonged to five genera (Amblyomma, Hyalomma, Rhipicephalus, Haemaphysalis, and Ixodes) and twelve species. Real-time PCR revealed that 23% (n = 218) of the ticks were positive for Rickettsia spp., 15% (n = 141) for bacteria of the Anaplasmataceae family, 3% (n = 29) for Piroplasmida, 0.5% (n = 5) for Coxiella burnetii, 0.4% (n = 4) for Borrelia spp., and 0.2% (n = 2) for Bartonella spp. The co-infection rate (3.4%, n = 32) involved mainly Rickettsia spp. and Anaplasmataceae. Of the Rickettsia spp. positive ticks, the targeted PCR and sequencing yielded Rickettsia africae (78.9%), Rickettsia aeschlimannii (6.4%), Rickettsia massiliae (7.8%), Candidatus Rickettsia barbariae (0.9%), and Rickettsia sp. (0.9%). Anaplasmataceae included Anaplasma marginale (4.3%), Anaplasma platys (1.4%), Anaplasma centrale (0.7%), Ehrlichia ruminantium (0.7%), Wolbachia sp., Candidatus Ehrlichia rustica (13.5%), Candidatus Ehrlichia urmitei (7%), and an uncultured Ehrlichia sp. (4.2%). Borrelia theileri was identified in one Rhipicephalus microplus tick. Unfortunately, Piroplasmida could not be identified to the species level. This study demonstrates that in Cameroon, ticks harbour a wide variety of microorganisms and present a risk of zoonotic diseases.

Entomopathogenic fungi and plant natural products against cattle tick Rhipicephalus microplus (Acarina: Ixodidae)

Entomopathogenic fungi and plant natural products against cattle tick Rhipicephalus microplus (Acarina: Ixodidae)

Diversity of Rickettsiales in Rhipicephalus microplus Ticks Collected in Domestic Ruminants in Guizhou Province, China

Rhipicephalus microplus ticks are vectors for multiple pathogens infecting animals and humans. Although the medical importance of R. microplus has been well-recognized and studied in most areas of China, the occurrence of tick-borne Rickettsiales has seldom been investigated in Guizhou Province, Southwest China. In this study, we collected 276 R. microplus ticks from cattle (209 ticks) and goats (67 ticks) in three locations of Guizhou Province. The Rickettsia, Anaplasma, and Ehrlichia were detected by targeting the 16S rRNA gene and were further characterized by amplifying the key genes. One Rickettsia (Ca. Rickettsia jingxinensis), three Ehrlichia (E. canis, E. minasensis, Ehrlichia sp.), and four Anaplasma (A. capra, A. ovis, A. marginale, Ca. Anaplasma boleense) species were detected, and their gltA and groEL genes were recovered. Candidatus Rickettsia jingxinensis, a spotted fever group of Rickettsia, was detected in a high proportion of the tested ticks (88.89%, 100%, and 100% in ticks from the three locations, respectively), suggesting the possibility that animals may be exposed to this type of Rickettsia. All the 16S, gltA, groEL, and ompA sequences of these strains are 100% identical to strains reported in Ngawa, Sichuan Province. E. minasensis, A. marginale, and Candidatus Anaplasma boleense are known to infect livestock such as cattle. The potential effects on local husbandry should be considered. Notably, E. canis, A. ovis, and A. capra have been reported to infect humans. The relatively high positive rates in Qianxinan (20.99%, 9.88%, and 4.94%, respectively) may indicate the potential risk to local populations. Furthermore, the genetic analysis indicated that the E. minasensis strains in this study may represent a variant or recombinant. Our results indicated the extensive diversity of Rickettsiales in R. microplus ticks from Guizhou Province. The possible occurrence of rickettsiosis, ehrlichiosis, and anaplasmosis in humans and domestic animals in this area should be further considered and investigated.

Experimental vaccination in rabbits using the peptide RmS-17 antigen reduces the performance of a Mexican Rhipicephalus microplus tick strain

The tick vector Rhipicephalus microplus is considered one of the main problems in cattle production in tropical and subtropical regions. Anti-tick vaccines may form an alternative tick control method to the use of acaricides, and tick salivary proteins, such as Serpins, may be valuable as target antigens for developing anti-tick vaccines. In this study, we synthesized a recombinant peptide derived from Serpin RmS-17 protein using an Escherichia coli expression system and characterized the efficacy of the peptide RmS-17 for the control of R. microplus females infesting rabbits. Twelve New Zealand white rabbits were assigned to three experimental groups and vaccinated with three subcutaneous doses of the peptide RmS-17, recombinant R. microplus Bm86 antigen, and adjuvant/saline alone. The tick challenge was conducted with 120 R. microplus adults (60 females and 60 males) per animal, with the ticks placed inside a cotton sleeve glued to the back of the rabbit. Serum antibody levels (IgG) were assessed by ELISA and confirmed by Western blot; also, the reproductive performance of R. microplus was determined. The results showed that experimental vaccination in rabbits using the peptide RmS-17 antigen had a vaccine efficacy of 79% based on reductions in adult tick number, oviposition, and egg fertility compared to control animals. The peptide RmS-17 vaccinated rabbits developed a strong humoral immune response expressed by high anti-pRmS-17 IgG levels, and the Western blot analysis confirmed that it is immunogenic. The efficacy for the Bm86 vaccine was 62%, which is within the range of efficacy reported previously for Bm86 vaccine. The negative correlation between antibody levels and reduction in tick number strongly suggests that the effect of the vaccine was the result of the antibody response in vaccinated rabbits. In conclusion, this is the first study to evaluate the efficacy of the peptide RmS-17 against R. microplus tick infestation and show it to be immunogenic and protective in a rabbit model.

Phytochemical investigation and evaluation of acaricidal activities of Datura stramonium fruits against Rhipicephalus microplus

Aim: The present study focused on the evaluation of acaricidal efficacy of ethanolic extract of fruits of Datura stramonium against cattle tick Rhipicephalus microplus in-vitro. The ethanolic extract of fruits of Datura stramonium were analysed for the presence of phytochemicals responsible for antitick activities. Methodology: The fruits of Datura stramonium were dried, blended, powdered and extracted in ethanol using Soxhlet’s apparatus. In-vitro tests like Adult Immersion Test and Larval Packet Test were utilized to assess the effect of plant extract by utilizing engorged R. microplus female. Reproductive Index, Inhibition of oviposition, adult and larval mortality of female ticks were observed. The phytochemicals present in the ethanolic fruits extract of D. stramonium were assessed by Gas chromatography-Mass spectroscopy and Fourier Transform Infra-red Spectroscopy. Results: The present study indicated anti tick activities of ethanolic extract of Datura stramonium fruit against Rhipicephalus microplus by reporting a mortality of 66.67%, Reproductive Index (0.11-0.16), Inhibition of oviposition ( 70.62%) and larval mortality (65%) at 100 mg ml-1 and LC50 value was determined to be 61.66 mg ml-1. There was dose dependant mortality of adult and larva and inhibition of reproduction. The ethanolic fraction's spectral examination revealed 31 components, with the presence of 2(4H)-Benzofuranone, 5,6,7,7a-(7.24), Hexadecanoic acid, methyl ester (9.16), 9,12,15-Octadecatrienoic acid, methyl ester (9.35), 9,12,15-Octadecatrienoic acid (15.17), 2-Propenoic acid, 3-phenyl-, methyl ester (32.87) as major phytocompounds. Interpretation: These results showed that ethanolic extract of Datura stramonium fruits are source of phytochemicals with antitick activities. The findings would be useful to the pharmaceutical industries for developing of ecologically friendly natural acaricides. Key words: Acaricides, Datura stramonium, Ethanolic extract, Rhipicephalus microplus, Ticks

Efficacy of essential oil of Lippia sidoides (Verbenaceae) for controlling the cattle tick Rhipicephalus (Boophilus) microplus on naturally parasitized animals under field conditions

Efficacy of the essential oil of Lippia sidoides to control the bovine tick Rhipicephalus (Boophilus) microplus was evaluated in tests on naturally infested cattle under field conditions. Twenty cattle were allocated to one of two groups (Control and Treated). Animals in the treated group were sprayed with three liters of 1 % L. sidoides solution (10,000 ppm) and efficacy was calculated from teleogynous counts between 4.5 and 8 mm in length before (days −3, - 2 and - 1) and after treatment (days +3, +7, +14, +21 and +28). The essential oil of L. sidoides showed an average efficacy of 50.7 % between days + 3 and + 21, with greater efficacy in the larvae (63.2 % - p = 0.0001).