Search

Boophilus microplus is a major cattle tick specie causing great economic loss to the dairy industry throughout the globe including Pakistan. Trichlorfon and Deltamethrin are used to control bovine ticks, and their sprays are also used in other pest control programs that exert pressure on ticks to gain resistance. This study is aimed to examine the resistance level of Rhipiciphalus microplus against trichlorfon and deltamethrin. The engorged ticks were collected from two ecological regions of Khyber Pakhtunkhwa, KPK Pakistan i.e., Swat & Dir (zone-1), and Charsadda & Nowshera (zone-2). Four concentrations of acaricides in two-fold and ten-fold ppm with three replicates for each were used in both bioassays. Egg hatch assay and adult immersion tests were used to assess the resistance status. The probit analysis of egg hatch assay showed the highest hatching percentage in zone 1 on both dilutions (67-76% on two-fold and 68-88% on ten-fold dilution) while lethal concentration (LC95) was found to be 2.187 ppm and discriminating dose (DD) as 4.374 ppm for trichlorfon. In zone 2, hatching percentage was 73-84 on two-fold and 72-91% on ten-fold dilution while LC95 was recorded as 0.599 ppm and DD as 1.198 ppm. The same parameters were studied for deltamethrin and in zone 1 the hatching percentage was found as 38-56% on two-fold dilution and 37-80% on ten-fold dilution while LC95 was recorded as 0.001 ppm and DD as 0.002 ppm. In zone 2, the hatchability was recorded as 42-58% on two-fold and 43-85% on ten-fold dilution. The values for LC95 was recorded as 0.001 ppm and DD as 0.002 ppm. Further, analysis of adult immersion test against trichlorfon revealed the values of LC50 as 2.85 ppm and LC95 as 4.71 ppm in zone 1 and in zone 2 as 3.14 ppm and 5.28 ppm, respectively. Similarly, LC50 and LC95 against deltamethrin was recorded as 0.79 ppm & 1.71 ppm in zone 1 and 0.45 ppm & 4.325 ppm in zone 2, respectively. Based on the findings of this study, the isolated Rhipicephalus microplus was found to be more resistant to the widely used acaricides i.e., trichlorfon than deltamethrin. In order to maintain the efficacy of acaricides at country level, the study recommends continuous monitoring of resistance. Resumo Boophilus microplus é uma das principais espécies de carrapatos bovinos, causando grandes perdas econômicas para a indústria de laticínios em todo o mundo, incluindo o Paquistão. Triclorfon e deltametrina são usados no controle de carrapatos bovinos, e seus sprays também são usados em outros programas de controle de pragas que exercem pressão sobre os carrapatos para ganhar resistência. Este estudo tem como objetivo examinar o nível de resistência de Rhipicephalus microplus contra triclorfon e deltametrina. Os carrapatos ingurgitados foram coletados de duas regiões ecológicas de Khyber Pakhtunkhwa, KPK Paquistão, ou seja, Swat & Dir (Zona 1) e Charsadda & Nowshera (Zona 2). Quatro concentrações de acaricidas em duas e dez vezes ppm com três repetições para cada foram usadas em ambos os bioensaios. O ensaio de eclosão de ovos e testes de imersão em adultos foram usados para avaliar o status de resistência. A análise probit do ensaio de eclosão de ovos mostrou a maior porcentagem de eclosão na zona 1 em ambas as diluições (67% na diluição de duas vezes e 68,33% na diluição de dez vezes), enquanto a concentração letal (CL95) foi de 2,187 ppm e dose discriminante (DD) como 4,374 ppm para triclorfon. Na zona 2, a porcentagem de eclosão foi de 73 em duas vezes e 72% em dez vezes, enquanto LC95 foi registrado como 0,599 ppm e DD como 1,198 ppm. Os mesmos parâmetros foram estudados para a deltametrina, e na zona 1 a porcentagem de eclosão foi de 38% na diluição de duas vezes e 37% na diluição de dez vezes, enquanto CL95 foi registrado como 0,001 ppm e DD como 0,002 ppm. Na zona 2, a eclodibilidade foi registrada como 42% na diluição de duas vezes e 43% na diluição de dez vezes. Os valores para LC95 foram registrados como 0,001 ppm e DD como 0,002 ppm. Além disso, a análise do teste de imersão de adulto contra triclorfon revelou os valores de LC50 como 2,85 ppm e LC95 como 4,71 ppm na zona 1 e na zona 2 como 3,14 ppm e 5,28 ppm, respectivamente. Da mesma forma, LC50 e LC95 contra deltametrina foram registrados como 0,79 ppm e 1,71 ppm na zona 1 e 0,45 ppm e 4,325 ppm na zona 2, respectivamente. Com base nos achados deste estudo, o isolado Rhipicephalus microplus mostrou-se mais resistente ao acaricida amplamente utilizado, ou seja, triclorfon do que deltametrina. Para manter a eficácia dos acaricidas em nível nacional, o estudo recomenda o monitoramento contínuo da resistência.

The resistance status against deltamethrin, cypermethrin, coumaphos and ivermectin was assessed of Rhipicephalus microplus from five districts of Uttarakhand, through adult immersion test and larval packet test. The field isolates were highly resistant to deltamethrin (median resistance ratio [RR50] = 9.10-29.13-fold) followed by cypermethrin (2.23-3.55). Surprisingly the isolates were susceptible to coumaphos (0.34-3.17). Emerging resistance against ivermectin (1.55-3.27) was also observed in all the isolates. Elevated levels of esterases (enzyme ratio = 2.93-5.84-fold), glutathione S-transferases (5.10-10.06) and monooxygenases (1.68-4.02) in resistant fields isolates were highly correlated (47.4-86.0%) with the resistant factor (RR50) determined by bioassay. All the isolates except Uttarkashi possess mutation at the 190th position in domain II of the sodium channel gene. As a mitigation strategy an Ageratum conyzoides-based characterized natural formulation was tested against all the isolates and was found effective at the concentration of 10.1-11.5%. The possibility of using the natural formulation for the management of multi-acaricide resistant ticks is discussed.

Beauveria bassiana (Hypocreales: Cordycipitaceae) is an entomopathogenic fungus that has shown promising results as a biocontrol agent of ticks. Locally isolated B. bassiana are better acclimatised to the natural conditions of their geographical origin; therefore, they are essential in developing effective biocontrol agents for ticks. The current study aimed to isolate native strains of B. bassiana that are pathogenic to Rhipicephalus microplus ticks. The virulence of the isolates was tested against R. microplus larvae using a formulation containing 15% avocado oil, 0.05% adjuvant and 108 conidia mL-1. The two best strains were further evaluated for various biological parameters on adult engorged female ticks. Breakthru® or Ballista® (adjuvant) was mixed with the formulation to compare their effect on the isolates' virulence. In total 61 entomopathogenic fungi were isolated from the 360 greater wax moth larvae, Galleria mellonella (Lepidoptera: Pyralidae) used. The virulence test identified Bb-40 and Bb-41 to be the most virulent isolates against R. microplus larvae with mortalities of 91 and 93% and LT50 values of 5.8 and 6.2 days, respectively. Compared to the control, both strains significantly affected all the measured biological parameters. The type of adjuvant also considerably affected the susceptibility of ticks to the fungi. In conclusion, the two isolates combined with adjuvants can be used as a biocontrol agent to control R. microplus.

One of the main health problems in cattle farming is infestations caused by ticks. The most important species is Rhipicephalus microplus, which affects 80% of bovine population worldwide. Its control is mainly based on the use of ixodicides. However, excessive and inappropriate use has generated multi-resistant strains of ticks. Alternatively, immune control has been proposed as an important method to reduce tick populations. The recombinant Bm86 vaccine is the only commercially available and reports variations in its efficacy due to polymorphisms in the gene's coding sequence. Therefore, this work aimed to characterize an immunogenic region of Bm86 strain R. microplus "Media Joya" to propose a vaccine candidate that is conserved and with minimal variability in its efficacy. Computational tools, molecular biology techniques, and phylogenetic analysis were used. As a result, an immunogenic region consisting of 178 amino acids and 98-100% identity/similarity were obtained concerning strains of R. microplus ticks from the Americas. Furthermore, is necessary to evaluate the immunoprotective potential of the Bm86 region characterized in this work as an anti-tick vaccine.

Tick-borne viruses and bacteria that can cause diseases of animals and humans have high impact and are of concern as significant threats to human health worldwide. In this research, we screened microorganisms related to those pathogens in ticks from dogs, a cat, and a cow. The techniques used were PCR, DNA sequencing and phylogenetic analysis to detect and classify the microorganisms [Flavivirus, severe fever with thrombocytopenia syndrome virus (SFTSV), Phlebovirus, Coronavirus, Canine Parvovirus, eubacteria, Coxiella and Rickettsia]. A novel virus named Phlebovirus-like-AYUT and Stenotrophomonas maltophilia bacteria were found in one individual tick (Rhipicephalus sanguineus s.l.) from a dog. All tick samples were negative for Rickettsia, while 9/21 (42.9 %) were positive for Coxiella bacteria. The novel virus “Phlebovirus-like-AYUT” (the name derives from Phra Nakhon Si Ayutthaya Province in Thailand) was resolved by phylogenetic analysis of the partial L segment by maximum likelihood (ML) method using MEGA X. The phylogenetic tree also indicated that the virus was related to Phlebovirus in brown dog ticks reported in Trinidad and Tobago. In contrast, Phlebovirus-like-AYUT was in a distinct clade from Lihan tick Phlebovirus-Thailand (LTPV), which was previously found in cow ticks, Rhipicephalus microplus, in Nan Province, Thailand. This study reports the Stenotrophomonas maltophilia bacterium with a novel Phlebovirus-like-AYUT in a brown dog tick. The roles of this bacterium in a virus-positive tick or in viral transmission from animal host requires further investigation.

Although different evaluations on the efficacy of the strategic control against Rhipicephalus microplus have been performed, the effects of successive applications of these schemes on the abundance of cattle ticks have not been evaluated. The aim of this work was to analyse the long-term effect of strategic applications of chemical acaricides on the R. microplus infestation in cattle in a subtropical area. These schemes are based on the application of three annual treatments between late winter and late spring. Additionally, a trial to evaluate the efficacy of the strategic control by deferring the first treatment from late winter to spring and the third treatment from late spring to summer was also carried out. The efficacy of the strategic control applied on 3 consecutive years was significant. The tick infestation in the treated group always remained at low levels, because mean number of ticks was almost never higher than 20. Regarding the trial where the third application of acaricide was deferred from spring to summer, and the first one from late winter to spring, the differences between treated and control group were significant in all post-treatment counts. The results of this study add evidence that support the sustainability of the strategic control in subtropical areas where the population dynamics of R. microplus is characterized by a well-marked seasonal pattern. Three relevant aspects were determined: (i) the feasibility and efficacy of successive applications of the strategic control in consecutive years; (ii) the time window to start the sequence of treatments is from late winter to mid-spring; (iii) it is achievable deferring the last treatment from late spring to summer if the tick infestation levels on cattle are low enough to allow it.

An investigation was carried out to record the status of resistance against most commonly used synthetic pyrethroids, viz. deltamethrin and cypermethrin in Rhipicephalus microplus of Indore district (Madhya Pradesh). Fully engorged female R. microplus were collected from cattle sheds of four blocks of Indore district, viz. Indore, Hatod, Sanwer and Mhow. Ticks were kept individually for oviposition and eggs laid were allowed to hatch and larval packet test (LPT) was performed on 12 to 14 day-old-larvae with deltamethrin and cypermethrin. The slope of mortality, lethal concentration for 50% (LC50), 95% (LC95) mortality and resistance ratios (RR) were determined from the regression graphs of probit mortality of ticks plotted against log concentrations of deltamethrin and cypermethrin. Values of the coefficient of determination (R2) for LPT ranged from 0.94 to 0.96 and 0.93 to 0.99 for cypermethrin and deltamethrin, respectively indicating the statistical model a good fit. The LC50 and LC95 values for cypermethrin ranged from 49.31 to 117.21 and 193.23 to 683.7 ppm, respectively in various field isolates whereas, for deltamethrin were 10.71–23.80 and 45.26–194.98 ppm. The values of RR50 and RR95 for cypermethrin ranged from 0.2 to 0.48 and 0.55 to 1.94, respectively, showing variable resistance status in field populations. On the basis of RR50 values, susceptible status was recorded in all isolates whereas, level I resistance status was recorded in two field isolates (Sanwer and Mhow) on the basis of RR95. Similarly, for deltamethrin RR50 and RR95 ranged from 0.91 to 2.01 and 1.27 to 5.49, respectively, showing comparatively higher resistance status. Resistance status against deltamethrin was recorded in Mhow isolate (on RR50 basis) and Mhow, Sanwer and Hatod isolate (on RR95 basis). High level of resistance along with more number of resistant tick isolates were recorded in case of deltamethrin than that of cypermethrin from the study area.

Amitraz resistance status was estimated in cattle tick, Rhipicephalus microplus populations collected from fifteen districts of the Punjab state using adult immersion test. A two-minute immersion protocol with various working concentrations (1-500 ppm) of formulated amitraz (Taktic 12.5% EC) in distilled water was adopted. The regression graphs of probit mortality of engorged female ticks against log concentrations of amitraz were utilized for estimation of slope of mortality, lethal concentration for 50% (LC50), 99% (LC99) and resistance factors (RF). The values of RF were found to be in the range of 0.20-4.55 indicating low level resistance status in eight field populations, whereas, seven were found susceptible to amitraz. Effects of amitraz on the various reproductive parameters of engorged R. microplus viz. egg mass weight, reproductive index, percentage inhibition of oviposition and hatchability percentage were assessed and found to be dose dependent and more discernible upon exposure with higher concentrations.

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 100 mg/mL. Randia aculeata (seed and shell), M. oleifera and C. papaya treatments at the same concentration (100 mg/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 100 mg/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.

Rhipicephalus microplus is the main blooding-sucking ectoparasite of bovines and is regarded as important vectors of animal diseases such as Babesiosis. Mining protective antigens of R. microplus to develop antitick vaccine is the most potential tick control strategy. In this study, the specific primers were designed according to the conserved nucleotide sequence of enolase gene in Haemaphysalis flava, Ixodes ricinus, and Ornithodoros moubata. The fragment of enolase gene was obtained by PCR using cDNA template from fully engorged female R. microplus. The full-length cDNA of enolase gene was amplified using rapid amplification of cDNA ends (RACE). Expression pattern of enolase gene in different tissues of R. microplus was analyzed by real-time quantitative PCR (qRT-PCR). Results showed that the full-length enolase cDNA containing 2052 bp was obtained successfully. The complete cDNA included an ORF of 1305 nucleotides encoding a protein of 434 amino acids. The enolase exhibited 85.0% amino acid identity to the enolase of H. flava, 81.1% to I. ricinus enolase, and 81.3% to O. moubata enolase. qRT-PCR analysis indicated that the enolase had the highest expression in the salivary gland of R. microplus.

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.

Background Studies on ticks infesting equids are lacking in various parts of the world, including Khyber Pakhtunkhwa (KP), Pakistan. The aim of this study was to investigate the diversity of ticks infesting equids, associated risk factors and rickettsial detection in ticks from equids in KP. Methods Inspection of 404 equid hosts from November 2018 to October 2019 resulted in the collection of 550 ticks. Data on tick-associated risk factors were collected from equid owners by means of a questionnaire. After morphological identification, partial DNA sequences of the tick mitochondrial 16S rRNA gene were used for taxonomic confirmation of species. Partial sequences of the gltA and ompA genes were used for Rickettsia detection in ticks. Results A total of 550 tick specimens were collected on 324 (80.2%) of the equids inspected, of which 161 were horses (50%), 145 (45%) were donkeys and 18 were mules (5%). The ticks were identified as belonging to the following five species: Rhipicephalus microplus (341 specimens, 62% of the total ticks), Rh. haemaphysaloides (126, 23%), Rh. turanicus (39, 7%), Rh. sanguineus (s.l.) (33, 6%) and Hyalomma anatolicum (11, 2%). The most prevalent tick life stage was adult females (279, 51%) followed by adult males (186, 34%) and nymphs (85, 15%). Higher tick infestations were observed on male equids (relative risk [RR] 0.7432, P P P P P P P P gltA and ompA genes obtained from Rh. microplus and Rh. haemaphysaloides were 100% identical to the spotted fever group pathogen Rickettsia massiliae. Conclusions Equids exposed to significant risk factors were infected by one or more of at least five tick species in KP, Pakistan, and some of the ticks harbored the human pathogen R. massiliae. Graphical abstract

This study was sought to devise pellets containing inorganic materials and microsclerotia of Metarhizium anisopliae strain IP 119 for biological control of Rhipicephalus microplus, the most economically important tick in Brazilian cattle industry. In addition, we evaluated the storage stability of the pellets, their tolerance to ultraviolet radiation (UV-B), and efficacy against ticks under laboratory conditions. Fungal microsclerotia were produced by liquid culture fermentation and mixed with pre-selected inorganic matrices: vermiculite powder, diatomaceous earth, and colloidal silicon dioxide (78:20:2, w/w/w). The microsclerotial pellets were then prepared by a two-stage process involving extrusion and spheronization. Pellet size averaged 525.53 ± 7.74 μm, with a sphericity index of 0.72 ± 0.01, while biomass constituents did not affect the wet mass properties. Conidial production from microsclerotial pellets upon rehydration ranged from 1.85 × 109 to 1.97 × 109 conidia g−1 with conidial viability ≥ 93%. Conidial production from pellets stored at 4 °C was invariable for up to 21 days. Unformulated microsclerotia and microsclerotial pellets were extremely tolerant to UV-B compared with aerial conidia. Engorged tick females exposed to conidia from sporulated pellets applied to soil samples and upon optimal rehydration exhibited shorter oviposition time length, shorter life span, and reduced number of hatched larvae. In summary, microsclerotial pellets of M. anisopliae IP 119 effectively suppressed R. microplus and showed outstanding UV-B tolerance in laboratory tests. Prospectively, this formulation prototype is promising for targeting the non-parasitic stage of this tick on outdoor pasture fields and may offer a novel mycoacaricide for its sustainable management. • Pellets with microsclerotia and inorganic materials are innovative for tick control. • Metarhizium microsclerotia show superior UV-B tolerance in relation to conidia. • Pellets of Metarhizium microsclerotia produce infective conidia against ticks.

Taurine breeds and animals crossbred for genetic resistance to Rhipicephalus microplus have been the focus of several studies aimed at producing better responses of cattle to tick infestations and seeking to reduce treatment costs and improve the quality of bovine byproducts. Another way to increase gains is the introduction of taurine breeds with the goal of obtaining morphological and physiological characteristics more adapted to production. Although several studies have compared taurine and zebu breeds, little is known about the differences found within the taurine group. Therefore, the present study aimed to evaluate the sensitivity of the Senepol and Caracu breeds to artificial R. microplus infestations. For this purpose, a stall test was conducted on 16 Caracu and 14 Senepol bulls. The animals were subjected to artificial infestation with a total of 15,000 R. microplus larvae per animal. The Senepol group accounted for 71.7% of the retrieved engorged female ticks. The biological parameters analyzed that showed a significant difference included the mean number of engorged female ticks retrieved (p = 0.000), weight of engorged female ticks (p = 0.000), rate of engorged female ticks retrieved (p = 0.03) and egg mass weight (p = 0.032). Thus, the present study demonst rated a higher susceptib ility of the Senepol breed to parasitism by the Asian blue tick than the Caracu breed, providing support for new studies on the subjects of genetic resistance, animal breeding and cattle production.

Bovine babesiosis is caused by apicomplexan pathogens of the genus Babesia, including B. bovis. This protozoan parasite has a complex life cycle involving dynamic changes to its transcriptome during the transition between the invertebrate and vertebrate hosts. Studying the role of genes upregulated by tick stage parasites has been hindered by the lack of appropriate tools to study parasite gene products in the invertebrate host. Herein, we present tfBbo5480, a transfected B. bovis cell line, constitutively expressing enhanced green fluorescent protein (eGFP) created by a whole gene replacement transfection strategy, that was capable of completing the parasite’s entire life cycle in both the vertebrate and invertebrate hosts. tfBbo5480 was demonstrated to respond to in vitro sexual stage induction and upon acquisition by the female tick vector, Rhipicephalus microplus, the tick specific kinete stage of tfBbo5480 was detected in tick hemolymph. Larvae from tfBbo5480 exposed R. microplus female ticks successfully transmitted the transfected parasite to a naïve calf. The development of the whole gene replacement strategy will permit a deeper understanding of the biology of parasite-host-vector triad interactions and facilitate the evaluation of upregulated genes during the parasite’s journey through the tick vector leading to new intervention strategies for the control of bovine babesiosis.

Background: There has recently been a substantial increase in the number of tick species and tick-borne infectious agents in Tanzania. Owing to their impact on human, livestock, and wild animal health, increased knowledge of ticks is needed. So far, no published data on the genetic relationship between hard tick (Ixodidae) sequences collected from cattle are available in Tanzania. Methods: Ticks from cattle in the wards, which lie at the border of Mikumi National Park, were collected in the dry season, November to December 2019. Morphological identification of ticks was initially performed at the genus level. To identify ticks at the species level, molecular analysis based on the 16S rRNA gene was performed. Evolutionary relationships and genetic distances between ticks were determined using MaximumLikelihood and Kimura 2-parameter methods, respectively. Results: Based on morphology, two genera (Rhipicephalus and Hyalomma) were identified in the 630 adult ticks collected from a total of 252 cattle. Six species (Rhipicephalus microplus, Rhipicephalus evertsi, Hyalomma marginatum, Hyalomma rufipes, Hyalomma truncatum, and Hyalomma turanicum) were confirmed by BLASTn and phylogenetic analyses. Considerable mean and pairwise genetic distances were observed for Rhipicephalus and Hyalomma genera. Conclusion: The presence of different phylogenetic clusters and considerable mean and pairwise genetic distances observed reflect possible biological diversity of hard ticks present in the study area. Considering the value of the cattle in the livelihoods and economies of people and the country, the outcomes of this study will be useful in planning integrated control strategies for ticks and tick-borne diseases in Tanzania.

Rhipicephalus microplus is an important ectoparasite of cattle, causing considerable economical losses. Resistance to chemical acaricides has stimulated the search for new antiparasitic drugs, incl...

The indiscriminate use of acaricides is a problem worldwide and has increased the selection of acaricide-resistant tick populations. The goal of this study was to evaluate the acaricide effects of two essential oils (from Schinus molle and Bulnesia sarmientoi) using the larval immersion test on three Rhipicephalus tick species. Rhipicephalus evertsi, Rhipicephalus appendiculatus and Rhipicephalus pulchelus ticks collected in Kenya, without history of acaricide exposure, were tested, as well as individuals from two populations of Rhipicephalus microplus (with or without history of acaricide exposure), for comparison. The sample most resistant to the treatments was a population of R. microplus with previous acaricide exposure, whereas the least tolerant sample was a strain of the same species that never had contact with acaricides (Porto Alegre strain). Interestingly, the field tick samples without previous acaricide exposure responded to essential oils with a mortality profile resembling that observed in the acaricide-resistant R. microplus field population, and not the susceptible Porto Alegre strain. The essential oil of B. sarmientoi and its two components tested (guaiol and bulnesol) caused the highest mortality rates in the tested species and are potential molecules for future studies on control methods against these species.

The study was conducted to determine the efficacy of commercially available chemical compound used in management of tick infestation in this area where the Rhipicephalus microplus is the most prevalent species of ticks. The most important chemical compound used for controlling ticks in this area is cypermethrin, deltamethrin and amitraz. This is happen because cheap and easy availability of these compound. The engorged female R. microplus tick sample was collected from unorganised dairy farm of Mhow districts in Madhya Pradesh. The Adult Immersion Test (AIT) and larval packet test (LPT) was performed for the characterization of resistance in field tick population. The slope of mortality, lethal concentration for 50 % (LC50), and resistance ratios (RR) were determined from the regression graphs of probit mortality of ticks plotted against log concentrations of chemical compound used in study. The resistant ration (RR) of cypermethrin was in the range of 0.76 to 1.45. Most of the population were found susceptibly in LPT and AIT and the slope value was recorded lower than the susceptible reference strain. In case of deltamethrin, the resistance ratio (RR) was in the range of 22.35 to 34.64 at level II and III and the slop value of field population was found comparatively low than susceptible reference strain. In amitraz, the resistance ratio (RR) was obtained as 2.23.On the basis of RR the tested tick showed resistance in adult stage at level I. The AIT bioassay was used for the characterization of resistance in field tick population. Efficacy of chemical compound was recorded on basis of resistance ratio and level of resistance was assessed. The data on field status of acaricide resistance in Mhow block of Madhya Pradesh state will be helpful to adopt suitable strategy to overcome the process of development of resistance in ticks.

Amitraz is an acaricide that is widely used in veterinary medicine to control the cattle tick Rhipicephalus microplus. However, controversy exists in the literature regarding the resistance of R. microplus to this product. The present work provides an update on the acaricidal efficacy of amitraz (Triatox®, 12.5 % amitraz) after 15 years without its use on a property. Two in vivo (bovines treated with amitraz and submitted to tick counts, n = 20 animals) and one in vitro (adult immersion test, n = 40 ticks) assays were performed to determine product efficacy. The efficacy of the commercial formulation tested in the first in vivo trial ranged from 14.1 to 47.0%, and in the second from 3.6 to 35.1%, for the 28 days of the experiments. Efficacy for the in vitro trial was 47.38%. The dose recommended by the manufacturer of the product did not cause mortality to most of the ticks of this strain, and efficacy/resistance was not reverted or modified after 15 years (estimated 60 tick generations).

A total of 2809 ixodid ticks were collected by screening 4560 household cattle from six different agro-climatic zones of Tamil Nadu, a southern state of India. Among the ixodid ticks, Rhipicephalus microplus tick isolates were subjected to Adult Immersion Test (AIT) and Larval Packet Test (LPT) using deltamethrin. The mean % of ixodid tick infested cattle population was 63.2%±10.9. Positive correlation was found between the tick burden on household cattle and Resistance Factor (R=0.66). Further, 44% variance in the tick burden on cattle is explained by LPT based resistance factor suggesting deltamethrin resistance level is one of the contributing factors to the tick load on cattle. Analysis of DNA sequence of sodium channel gene domain II-S4-5 linker region of all deltamethrin resistant R. microplus tick isolates, confirmed the absence of point mutation at the 190th nucleotide which suggests the possible mutation in other regions of sodium channel gene of R. microplus tick isolates of south India and/or alternate resistance mechanisms.

A survey to determine the prevalence of tick-borne diseases (TBDs) and ticks infesting cattle was conducted in the communal areas of the north-eastern region of the Eastern Cape Province (ECP) between January 2019 and October 2019. Tick counts, packed cell volume (PCV), body condition scores (BCS), and serological test for TBDs were seasonally conducted in communally grazed cattle (n = 240) in Joe Gqabi district in two local municipalities (Elundini and Senqu). A standard indirect fluorescent antibody test (IFAT) was used to determine antibodies to Babesia bigemina, Babesia bovis, and Ehrlichia ruminantium and indirect enzyme-linked immunosorbent assay (ELISA) was employed for antibodies to Anaplasma marginale detection. The highest tick loads were observed on cattle during the hot-wet and post-rainy seasons and lowest during the cool-dry season. The E. ruminantium prevalence in Elundini was 16% and 14% in post-rainy and hot-dry seasons respectively and 15% at Senqu during the post-rainy season. B. bigemina prevalence was highest at Elundini (18%) and Senqu (16%) during the post-rainy season and hot-wet season respectively. Cattle BCS was negatively correlated with E. ruminantium (P < 0.01; r = - 0.203), B. bovis (P < 0.01; r = - 0.125), and A. marginale (P < 0.01; r = - 0.122) seroprevalence. The PCV was negatively correlated with B. bigemina (P < 0.01; r = - 0.138) seroprevalence. On the other hand, E. ruminantium was positively correlated with Amblyomma hebraeum (P < 0.05; r = 0.112) infestation, while B. bovis (P < 0.05; r = 0.134) and B. bigemina (P < 0.05; r = 0.188) were positively correlated with Rhipicephalus microplus infestation, and B. bigemina (P < 0.05; r = 0.077) was positively correlated with Rhipicephalus decoloratus infestation. Our study reports for the first time the presence of R. microplus in the study area. Further research is, however, needed to better understand seroprevalence and the transmission mode of TBDs to cattle so that effective disease control measures can be developed.

In addition to pesticidal activity, the capacity of natural compounds to inhibit the reproduction of parasites emerge as an important alternative tick control method. In this context, Satureja spp. stand out due to their recognized pesticidal properties. Among parasites of veterinary importance, the cattle tick, Rhipicephalus microplus, is responsible for great economic losses in livestock and transmission of relevant pathogens. Thus, the aim of this study was to evaluate the effects of different concentrations of the essential oil of Satureja montana L. on the ovary morphology of R. microplus engorged females through histological and histochemical techniques. The most remarkable morphological changes found were: cytoplasmic vacuolation of germ cells, irregular and thicker chorion, irregular oocyte shape, ring-shaped nucleolus, decrease in protein and carbohydrate content in oocytes, in addition to cellular changes in the oviduct and pedicel. All morphological changes were assessed using a semiquantitative method already established in the literature. Ticks exposed to 5.0 μl/ml of essential oil showed the most significant changes when compared to control groups. Thus, the essential oil of S. montana L. damaged the reproductive system of R. microplus, which may impair ticks' offspring production and promote a long-term control of this species. HIGHLIGHTS: The essential oil of Satureja montana L. affects the ovary morphology of the cattle tick. The main morphological alterations found were cytoplasmic vacuolation, irregular and thicker chorion and irregular oocyte shape. These alterations may impair the development of eggs.

Livestock production is a fundamental source of revenue and nutrition, wherein cattle-farming constitutes one of the major agricultural industries. Vectors and vector-borne diseases constitute one of the major factors that decrease the livelihood of all farming communities, more so in resource-poor communities and developing countries. Understanding the immunological responses during tick infestation in cattle is instrumental in the development of novel and improved tick control strategies, such as vaccines. In this study, gene expression patterns were compared within the lymph nodes of three cattle breeds at different life stages of the cattle tick, Rhipicephalus microplus. For Bonsmara (5/8Bos taurus indicus × 3/8B. t. taurus) cattle specifically, some 183 genes were found to be differentially expressed within the lymph nodes during larval and adult tick feeding, relative to uninfested cattle. Overall, the data provides evidence for a transcriptional regulatory network that is activated during immature tick infestation, but is down-regulated towards basal transcriptional levels when adult ticks are feeding. Specific processes in the lymph nodes of Bonsmara cattle were found to be differentially regulated on a transcriptional level. These include: (1) Leukocyte recruitment to the lymph node via chemokines and chemotaxis, (2) Trans-endothelial and intranodal movement on the reticular network, (3) Active regulation of cellular transcription and translation in the lymph node (including leukocyte associated cellular regulatory networks) and (4) Chemokine receptors regulating the movement of cells out of the lymph node. This work provides a first transcriptome analysis of bovine lymph node responses in tick-infested cattle. Findings show a dynamic immune response to tick infestation for the Bonsmara cattle breed, and that suppression of the maturation of the cattle hosts' immunity is especially evident during the larval feeding stages.

Resistance to ivermectin in populations of the cattle tick Rhipicephalus microplus in Argentina was diagnosed in this work. The in vitro larval immersion test (LIT) was used to determine quantitatively the levels of resistance to ivermectin in different populations of R. microplus. Additionally, field trials to control natural infestations of R. microplus on cattle with a commercial formulation of ivermectin 3.15% were carried and jointly analyzed with the in vitro assays. The phenotypic response of the populations analyzed was not uniform. Five of them were classified as susceptible, four populations as resistant, and one in the category "incipient resistance". Regarding the field trials, the therapeutic efficacy in a population classified with LIT as susceptible achieved values higher than 94% two weeks after treatment, and no reproductively viable females were observed after the second day post-treatment. Conversely, the values of efficacy percentage in a population (named as "San Martín") classified with LIT in the category "incipient resistance" never exceeded the 70.8%, and engorged females were collected in practically all counts. The population "San Martín" was classified in the category "incipient resistant" with LIT analysis, but the field trial unambiguously shows that this tick population is resistant. The comparison of the results obtained with LIT in vitro assays and through field trials shows that biased estimations of resistance levels may occur when resistance ratios (RR) values are ≤2, and additional field efficacy trials could be needed to know with precision the status of the tick populations evaluated.

The efficacy of Allium sativum and Cannabis sativa against Rhipicephalus microplus ticks was evaluated using the adult immersion and the larval packet test. In addition, an in silico approach was utilized by performing a docking study in order to identify the active ingredients from both plants. Results showed a comparatively high lethal effect of A. sativum and C. sativa on egg laying (index of egg laying = 0.26 and 0.24, respectively), egg hatching (33.5 and 37.1, respectively), and total larval mortality (100%, both), at 40 mg/mL. When applied to cattle which had been inoculated with larvae ticks, it was observed that a 45% solution of both herbal extracts significantly reduced the number of ticks by 96 h post treatment. We analyzed in silico 27 known active molecules from both plants and identified in the PubChem database to explore the hypothesis that the effect found on ticks was based on inhibition of acetylcholinesterase (AChE). Vitamin E and cannabidiol are the most potent AChE inhibitors with docking scores of -15.85 and -14.38, respectively. Based on these findings, we conclude that A. sativum and C. sativa may potentially be used for the control of R. microplus, and should be further investigated as a potential supplement to or replacement of synthetic acaricides.

The ectoparasite Rhipicephalus microplus has caused huge economic losses in livestock, and its synthetic chemical control resulted in acaricidal resistant ticks, environmental damages and residues ...

Rhipicephalus microplus is the most significant tick of livestock and its control is particularly challenging due to its resistance to commercial acaricides. Pasture rotation is considered a management strategy that could help control R. microplus, however, the literature only contemplates mathematical models and little is known about the effects of this practice in the field. The objective of this work was to determine whether pasture rotation is an efficient method for controlling R. microplus. Two different experiments were performed that involved groups of continuous and rotational grazing bovines. Female ticks measuring 4.5-8.0 mm were counted on animals while larvae in pasture were counted using the flannel drag technique. Treatment for infested bovines was applied when the average group tick count was ≥30 females. The results showed that rotational grazing (with 20-day periods of rest) had a higher tick count on-host than continuous grazing (P 0.05) and additional bovine treatment was needed. Sixty and 105 days were needed to re-infest and disinfest pasture of R. microplus larvae, respectively. The first treatment of bovines occurred 91 days after the animals were placed in a closed area. The results indicate that rotational grazing is not an efficient way to control R. microplus.

Fipronil is a broad spectrum phenylpyrazole compound which is recently used in field condition for the control of the tick, mites, flea and flies population in domestic animals and pets. It is used more often in organised cattle farms to avoid fly menace and concurrently reduce tick infestation. Repeated exposure of fipronil to cattle ticks, Rhipicephalus microplus and Hyalomma anatolicum might have led to the emergence of acaricide resistance. The objective of this study was to estimate fipronil sensitivity in field ticks collected from 8 different farms of Haryana (India) using FAO recommended larval packet test. Out of these, four cattle farms were found infested with both R. microplus and H. anatolicum; one farm at Sirsa district of Haryana comprises of H. anatolicum exclusively whereas three other farms at Hisar and Bhiwani districts of Haryana showed only the presence of R. microplus ticks. The resistance factor for H. anatolicum against fipronil in larval packet test ranged from 0.23 to 3.8, whereas, it ranged from 2.4 to 28.2 for R. microplus ticks. The H. anatolicum isolates displayed lower resistance factor in comparison to R. microplus population indicating greater selection on one host tick and faster development of fipronil resistance. This article reports for the first time the emergence of fipronil resistance in Western part of Haryana and highlights the beginning of fipronil resistance in H. anatolicum ticks which is responsible for high incidence of bovine tropical theileriosis in Northern India.

Anaplasmataceae includes the genera Anaplasma, Ehrlichia, Neorickettsia and Wolbachia, comprising a group of obligate intracellular bacteria. The genus Anaplasma has pathogenic species transmitted by ticks of veterinary and human health importance. Wild ungulates such as deer represent important reservoirs and amplifiers of Anaplasmataceae. The interaction between deer and domestic ruminants represents a serious problem due to the transmission of these pathogens through their ectoparasites. In the present study, we investigated the presence of Anaplasmataceae organisms in blood, tissues and tick samples of a gray-brocket deer (Mazama gouazoubira). The specimen was found dead in a farm in northeast Uruguay. PCRs targeting partial regions of 16S rRNA and groESL genes were carried out for Anaplasmataceae DNA detection. Moreover, several ectoparasites were identified: the chewing louse Tricholipeurus albimarginatus, the Neotropical deer louse fly Lipoptena mazamae, and the ticks Haemaphysalis juxtakochi and Rhipicephalus microplus. A consensus sequence of 1274 bp of 16S rRNA was generated for Anaplasma sp. from the M. gouazoubira blood sample. All ticks analysed by PCR assays were negative. No band was detected in any of the samples after PCR targeting groESL gene. Phylogenetic analysis using 16S rRNA partial gene sequences, clustered the putative novel genotype sequence obtained in this study, named Anaplasma sp. genotype Mazama-Uruguay, along with Anaplasma sp. detected in Mazama sp., Mazama americana and Mazama bororo, all deer species from Brazil. Furthermore, this cluster showed to be closely related to Anaplasma bovis sequences obtained from various ruminants and other mammals from several parts of the world. The pathogenicity as well as its infecting potential to other cervids or domestic ruminants is currently unknown. Further studies should be performed in order to characterize this novel species, especially targeting other genes.

Background: Acaricide resistance is a central problem for the control of the cattle tick Rhipicephalus microplus. Genetic changes that confer resistance get fixed in the population, however, the physiological effects and phenotypes of these mutations are not always well understood or characterized. Single Nucleotide Polymorphisms (SNPs) in the para-sodium channel gene that confer cypermethrin knockdown resistance (kdr) were identified in several arthropods, and homologous mutations have been reported in R. microplus populations. To our knowledge, R. microplus populations that have these homologous SNPs have been associated and correlated with pyrethroid resistance but there is no direct physiological evidence that their presence does confer kdr in this organism. Methods: Resistance profiles from resistant and susceptible strains used in this work were obtained using the larval packet discriminating dose assay. The relevant genomic regions of the para-sodium channel of these strains were amplified using standard PCR; SNPs were detected by sequencing the corresponding amplicons. Ovary response to cypermethrin exposure/treatment was evaluated using videometrical analysis.Results: In this work we present historical evidence that the pyrethroid resistance trait is stable in a resistant reference strain after many years without selection, thus suggesting that the primary resistance mechanism is caused by mutations fixed in the population. In our experimental system, the mechanism that allows the maintenance of the contraction of the ovary after treatment with pyrethroids, is likely to be mediated by a change in the structure of the presynaptic para-sodium channel. We found that the resistant strain has the G184C, the C190A and the T2134A mutations in the para-sodium channel gene. SNPs G184C and T2134A have been reported to be genetically linked in resistant populations and are always found together. These mutations were confirmed to be absent in the susceptible strain used as control. Finally, using videometric analysis, we demonstrate that cypermethrin blocks ovary contraction in cypermethrin-susceptible ticks. We also show that ovaries from populations that carry the kdr associated SNPs still contract at cypermethrin concentrations that completely block ovary contraction in the susceptible strain. The configuration of the experimental system excludes a xenobiotic detoxification mechanism. Conclusions: This is the first report that presents physiological evidence that the presence of the G184C, the C190A, and the T2134A mutations in the para-sodium channel correlates with the ability of maintaining muscle contractility in R. microplus when exposed to cypermethrin. These results confirm that these SNPs may confer cypermethrin resistance in this organism by avoiding presynaptic blockage that in turn causes flaccid muscle paralysis that is characteristic of this acaricide. This work also demonstrates that the videometric assay that we previously validated can be used to detect more rapidly than other assays that involve larval mortality kdr-like cypermethrin resistant tick strains, because adult preengorged females can be directly assayed after they are collected on the field without waiting until eggs are laid and the larvae eclose.

The cattle tick Rhipicephalus microplus has a large impact on cattle production due to its bloodsucking habit and transmission of pathogens that cause babesiosis and anaplasmosis. Application of acaricides constitutes the major control method but is often accompanied by serious drawbacks, including environmental contamination and an increase in acaricide resistance by ticks. The recent development of anti-tick vaccines has provided positive results in the post-genomic era, owing to the rise of reverse vaccinological and bioinformatics approaches to analyze and identify candidate protective antigens for use against ticks. The ATAQ protein is considered a novel antigen for the control of the cattle tick R. microplus; it is expressed in midguts and Malpighian tubules of all ticks from the Rhipicephalus genus. However, genetic diversity studies are required. Here, the ATAQ gene was sequenced of seven R. microplus tick isolates from different regions in Mexico to understand the genetic diversity. The results showed that sequence identity among the Mexican isolates ranged between 98 and 100% and 97.8–100% at the nucleotide and protein levels, respectively. Alignments of deduced amino acid sequences from different R. microplus ATAQ isolates in Mexico revealed a high degree of conservation. However, the Mexican isolates differed from the R. microplus “Mozambique” strain, at 20 amino acid residues. Finally, the analysis of more R. microplus isolates, and possibly of other Rhipicephalus species, to determine the genetic diversity in the ATAQ locus is essential to suggest this antigen as a vaccine candidate that might control tick infestations.

The present study aimed to investigate the prevalence of cattle ticks and molecular identification of R. microplus in different ecological regions of North-Western Pakistan. A total of 1091 ticks w...

Made available in DSpace on 2020-12-12T01:31:19Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-08-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) The present study aimed to evaluate biological parameters of Rhipicephalus microplus in the non-parasitic phase in both field and laboratory conditions. It also aimed to assess correlations between duration (in days) of these parameters and climatic variables (humidity, rainfall, and soil temperature) and to estimate the annual number of generations of R. microplus in a tropical region. The non-parasitic phase of R. microplus in field and laboratory conditions was evaluated throughout the course of two years. A pasture was infested with engorged female of R. microplus, and biological parameters, including female pre-oviposition, female oviposition, egg mass incubation, larval pre-hatching phase, larval maturation, and larval longevity, were evaluated concomitantly with the collection of data on climatic conditions. The same parameters were also evaluated in a climatized chamber in the laboratory. The total duration of the non-parasitic phase in the field was longer in the dry season (1st and 4th life-cycle repetitions) than in the rainy season (2nd, 3rd, and 5th repetitions). Tick biological parameters for the non-parasitic phase in the laboratory were similar to those obtained in the field during the rainy season. The evaluated biological parameters were influenced mainly by environmental and ground-level temperatures, which modified egg mass incubation, larval pre-hatching, and larval longevity periods and, consequently, the total duration of the non-parasitic phase of the tick. The annual number of generations for the tick was estimated at five per year, which is alarming because it represents an increase, and so new studies into strategic control are needed. School of Agricultural and Veterinarian Sciences São Paulo State University (UNESP) University Center “Barão de Mauá” School of Veterinary and Zootechnics Federal University of Goiás Department of Medicine Veterinary Preventive School of Veterinary Federal University of Minas Gerais Brasil University Department of Biosciences and Technologies Institute of Tropical Pathology and Public Health Federal University of Goiás School of Agricultural and Veterinarian Sciences São Paulo State University (UNESP) FAPESP: 2014/14820-2

A study was conducted to investigate the tick infestation on cattle in the plain region of Chhattisgarh state. During the period of study, 832 ticks of 47 animals were examined for the different tick species. The most prominently infested ixodid tick belonged to Hyalomma anatolicum (68.38%) followed by Rhipicephalus microplus (30.40%).The females showed higher infestation than males. A single tick species infestation pattern was observed in 17 animals while 30 animals were infested by both tick species. Single species infestation of H. anatolicum was encountered in 15 animals while R. microplus was observed in 2 animals. The intensity of tick infestation on each animal varied from 6 to 65 ticks per animal at different locations.

Rhipicephalus microplus Canestrini, 1887 (Arachnida: Ixodidae) is a mandatory bloodsucking ectoparasite, and it is considered one of the main sanitary problems in livestock. In the development of new technologies for controlling ticks, Metarhizium anisopliae complex (M. anisopliae s. l.) Sorokın, 1883 (Ascomycota: Clavicipitaceae) have been shown to be an effective and safe alternative. However, when applied in the field, abiotic factors may directly influence their microbial activity, and different oily adjuvants enhance fungal efficacy, stability and viability under environmental conditions. Here, the efficacy of two Metarhizium anisopliae s.l. isolates (CG 148 and CG 347) were compared in mineral oil (MO) or vegetable oil (VO) emulsions to control cattle ticks under semi-natural conditions, as well as their persistence in the soil over time. Engorged female ticks were placed on the soil of grass pots previously treated or not with conidial oil-in-water emulsions. Both M. anisopliae s.l. oil-in-water emulsions tested were able to control R. microplus, achieving up to 100% daily efficacy, and remained viable in the soil for up to 60 days after treatment. These results show the prospective applicability of Metarhizium spp. to control the cattle tick and a real possibility for its control in the environment.

Essential and fixed oils have been researched as alternatives to chemical acaricides. The activity of volatile compounds from essential oils (1,8-cineole, citral and eugenol) at 1.0% (w/v) and fixed oil (castor oil) at 0.3% (w/v) dissolved in 2.0% (v/v) dimethyl sulfoxide (DMSO) + 0.2% (w/v) Tween 80® was assessed against Rhipicephalus microplus using immersion tests. 1,8-cineole (29.0%) and castor oil (30.2%) had the highest reproductive inhibition rate. A second experiment was performed to verify the effect of the 1,8-cineole (10.0% w/v) and, or castor oil (0.3% w/v) on tick reproduction using different solubilizing agents. The highest reproductive inhibition was observed for the combination of 1,8-cineole/castor oil (94.1%) and 1,8-cineole in 2.0% (w/v) sodium lauryl ether sulphate (SLES) (92.8%). A third experiment showed morphological changes in R. microplus oocytes at different stages of development, as well as in pedicel cells. The most intense effects were observed when ticks were immersed in the formulation containing 1,8-cineole (10.0% w/v) and castor oil (0.3% w/v) dissolved in 2% (w/v) SLES. These findings highlight the potential of this formulation as an alternative for managing cattle ticks as their cytotoxic effects can reduce R. microplus reproductive success.

Ixodids suck blood from host animals and transmit pathogens that cause important medical and veterinary diseases. As synthetic conventional acaricide resistance becomes increasingly common, alternative tactics are likely to enhance control efforts. Laboratory bioassays assessed the lethality of CimeXa, a commercial silica gel desiccant dust, and EcoVia, a commercial product containing silica gel + thyme oil, against lone star tick, Amblyomma americanum (L.), larvae and nymphs. Both life stages were completely killed by CimeXa by 24 h, and EcoVia achieved total larval mortality within 1 h when they were initially immersed in the dusts and when they crawled across treated substrate. Larvae were killed faster than nymphs. Temporary immersion of A. americanum larvae and nymphs in aqueous suspensions of the dusts were less effective than exposure to the dusts applied dry. Larval and nymphal mortality associated with crawling on dried aqueous suspensions of the products was also not as strong as when the immature life stages crawled across substrate treated with dry dusts, and EcoVia was not more efficient than CimeXa. CimeXa and EcoVia can likely be used to protect cattle in a prophylactic context because silica gel does not degrade, and EcoVia might be effective at eliminating ticks that are feeding on cattle as well. We suggest that the two dust products be assessed for efficacy against other ixodid species, such as the southern cattle fever tick, Rhipicephalus microplus (Canestrini), which transmits the causal agents of babesiosis to cattle.

This study aimed to evaluate Metarhizium anisopliae (Metschn.) Sorokin (Hypocreales: Clavicipitaceae) persistence in the soil and its impact on Rhipicephalus microplus Canestrini (Acari: Ixodidae) larval recovery in a semifield trial after the treatment of female ticks. Nine strains from the genus Metarhizium Sorokin were isolated from the soil in Brazil and taxonomically classified using the ef1-α gene. The thermotolerance of the strains and their in vitro virulence to tick larvae were tested. One M. anisopliae strain was selected and formulated for the semifield test. The presence of M. anisopliae in the soil ranged from 0.4 × 105 to 1.4 × 105 colony forming units per gram of soil after the treatment during the five months of the survey. The fungus-treated grass pots had significantly fewer larvae than did the control pots. Evidence was gathered about the soil persistence of a native M. anisopliae strain and its efficacy in the biological control of ticks.

Protocols to determine metabolic resistance in ticks were mainly derived from reports published using mosquitoes and agriculturally important insects without prior standardization. In the present study, biochemical assays were standardized to quantify acaricide metabolizing enzymes in tick homogenates. Three variables viz., age, number of larvae and reaction time were optimized using reference susceptible IVRI-I and deltamethrin resistant IVRI-IV (Resistance Factor = 194) tick strains. The optimum conditions for estimation of general esterases were 10-15 day old 40 larvae with 15 mins reaction time, 15-20 day old 40 larvae with 20 mins reaction time for Glutathione S- transferase, while 10-15 day old 80 larvae with 5 mins reaction time for monooxygenase. The standardized protocols were further validated in multi acaricide resistant strain (IVRI-V) and in nine field isolates having variable resistant factors to different acaricides. In all the nine heterogeneous field isolates, a significant correlation (p .05) between resistance to synthetic pyrethroids and over-expression of esterases and monooxygenase was noticed. Similarly, esterases and GST activities were significantly correlated with resistance to organophosphates. The details of the assay protocol are explained for adoption in different laboratories.

The current description of biological transmission of Anaplasma marginale by Rhipicephalus microplus ticks, includes both intrastadial and transstadial transmission. Both transovarial transmission of Anaplasma from engorged ticks to their progeny and, transmission from infected unfed larvae to the mammalian host are is controversial. In order to demonstrate vertical transmission of A. marginale by R. microplus ticks under experimental conditions, feed-acquisition infected engorged females were incubated at 18° C or 28° C for oviposition. Larvae hatched from these ticks were used to infest two steers for each incubation temperature. None of the four steers infested with either lot of larvae developed clinical disease, yet subclinical infection was observed in the steers infested with larvae from engorged ticks incubated at 28°. DNA from larvae used for the infection of the carrier tick donor, Only DNA from larvae oviposited at 28 oC, DNA from blood of positive steers were positive for amplification of msp5 and msp1α variable region by PCR. All other DNA samples from the original stabilate, blood from the donor steer, larvae from ticks incubated at 28° C and steers infested with these same larvae were positive both to msp5 and msp1α PCR. msp1α sequences of all PCR products were the same and coincided with previously reported Tlapacoyan-2 sequence. The present evidence indicates that R. microplus is capable of transmitting A. marginale to its progeny and that these infected larvae can transmit the infection to susceptible hosts.

Environmental stress conditions compromise the effectiveness of microorganisms for use in biological control. We investigated the thermotolerance of seven Metarhizium isolates from Central Brazil to 32 °C, and the thermotolerance of conidia of Metarhizium anisopliae s.str. IP 119 (Metchnikoff) (Hypocreales: Clavicipitaceae) and M. robertsii formulated in oil-in-water emulsion to 45 °C. We also evaluated the efficacy of oil-formulated conidia of M. anisopliaes.str. IP 119 against the tick Rhipicephalus microplus (Canestrini) (Acari: Ixodidae) under stress conditions (32 °C; 75% RH). The conidial germination on tick’s cuticle was assessed by Scanning Electron Microscopy. Conidia of M. anisopliaes.str. IP 119 formulated in oil-in-water emulsion caused significant control (59.4%) of R. microplus, even when treated ticks were incubated under stress (32 °C; 75% RH). Metarhizium spp. incubated at 32 °C had both decreased radial growth and conidial production. Conidia of IP 119 formulated in oil-in-water emulsion were more tolerant to 45 °C than conidia suspended in water. An oil-in-water emulsion protected M. anisopliaes.str. conidia against heat and dry conditions and may enhance its efficacy to control ticks by improving the tolerance of fungi against adverse environmental factors.

The potential for reinvasion of the United States by cattle fever ticks, Rhipicephalus (Boophilus) annulatus and Rhipicephalus microplus (Canestrini), which remain established in Mexico, threatens the viability of the domestic livestock industry because these ticks vector the causal agents (Babesia bovis and Babesia bigemina) of bovine babesiosis. The Cattle Fever Tick Eradication Program safeguards the health of the national cattle herd preventing the reemergence of bovine babesiosis by keeping the United States free of cattle fever ticks. Here, the collection of free-living southern cattle tick, R. microplus, larvae by sweeping flannel flags over vegetation in the wildlife corridor of Cameron and Willacy Counties, TX, is reported. Finding R. microplus larvae on vegetation complements reports of infestations in wildlife hosts inhabiting the southern Texas coastal plains. Land uses and environmental conditions have changed since cattle fever ticks were eradicated from the United States by 1943. These changes complicate efforts by the Cattle Fever Tick Eradication Program to keep cattle in the United States free of the cattle fever tick disease vectors. Current scientific research on technologies that could be used for area-wide management of fever tick larvae in south Texas and how this could be applied to integrated eradication efforts are discussed.

The cattle tick Rhipicephalus microplus causes significant economic losses to cattle production systems and is a main barrier to the introduction of Bos taurus breeds and their crosses in Brazil. These breeds have the genetic potential to generate animals that are more productive, but they are also more susceptible to R. microplus. One of the alternatives for conventional tick control is the use of strategic control, aiming at delaying or even preventing the development of its resistance to acaricides. The present study aimed to evaluate the economic losses caused by tick infestation on the productive performance of two breeds of beef cattle and to evaluate the economic efficiency of tick strategic control and its impacts on beef cattle production systems. Animal weights were obtained from the literature and were used to calculate the weight loss in kilograms (kg) and the economic loss (US$) caused by R. microplus infestation. The cost/loss ratio of performing strategic control was also calculated. The data show that tick infestation causes economic losses to the breeds and groups of animals evaluated and reduces animal performance (weight loss). The results show a loss of US$34.61/animal in the backgrounding phase and US$7.97/animal in the finishing phase for Brangus animals and its crosses. In conclusion, the data show that strategic control is economically efficient for Brangus animals in the backgrounding phase, independent of the methods used for acaricide application.

Intensive use of chemical acaricides for the control of cattle ticks (Rhipicephalus microplus) has led to the development of multiple acaricide resistance in Colombia. The present study aimed to characterize, using toxicological bioassays and molecular biology techniques, the resistance profile of a tick strain isolated from the Arauca state, Northeast Colombia. Commercial acaricides were used in adult immersion tests to determine its in vitro efficacies. Deltamethrin showed very low activity (4-7.3%), a mixture of cypermethrin and chlorpyrifos had intermediate efficacy (64-75.2%), and ethion presented the highest activity (88.5-100%). A colony (Arauquita strain) was established and larval immersion tests confirmed high resistance level to deltamethrin (241-fold) and susceptibility to ivermectin. A quantitative polymerase chain reaction-high resolution melt technique was used to identify single nucleotide polymorphisms (SNPs) in the para-sodium channel gene. All of the genotyped individuals were mutant, presenting one (n = 7), two (n = 7) or three (n = 9) SNPs previously associated with pyrethroid resistance. Sequencing revealed a novel mutation (F712L), that was found for the first time in R. microplus ticks from South America. This is the first description of mutations associated with pyrethroid resistance in R. microplus from Colombia. The acaricide resistance pattern found in the Arauquita strain is similar to other parts of Colombia.

Background and Aim: Ticks (Ixodidae) not only cause blood loss in cattle but also serve as vectors for various diseases, thus causing direct and indirect losses. Moreover, tick infestation can cause significant economic losses. This study aimed to identify the diverse species of ticks infesting cattle in five different regions in Indonesia. Materials and Methods: Tick specimens were obtained from local cattle in five different areas in Indonesia. The morphology of the specimens was macroscopically and microscopically evaluated, and the resulting data were descriptively and qualitatively analyzed. Results: In total, 1575 ticks were successfully collected from 26 animals. In total, two genera and three species, namely, Rhipicephalus microplus, Haemaphysalis bispinosa, and Rhipicephalus pilans, were identified. The cattle in Yogyakarta and Riau were infested by H. bispinosa, while the cattle in Sukabumi, Bali, and Lombok were infested by R. microplus and R. pilans. The level of infestation varied among regions, with R. microplus being the most commonly found species. Conclusion: The results of this study revealed that cattle in different regions of Indonesia were infested by variable numbers of tick species. In particular, the cattle in Yogyakarta and Riau were solely infested by H. bispinosa; this is a new finding in terms of the distribution of tick species in the country. Increased tick infestation in cattle decreases productivity and causes health problems; therefore, it deserves serious attention. Our findings can help in the formulation of an effective strategy for controlling and preventing cattle tick infestation in the country.

Slow pyrolysis is a process for the thermochemical conversion of biomasses into bio-oils that may contain a rich chemical composition with biotechnological potential. Bio-oil produced from crambe fruits was investigated as to their acaricidal effect. Slow pyrolysis of crambe fruits was performed in a batch reactor at 400°C and chemical composition was analyzed by gas chromatography-mass spectrometry (GC-MS). The bio-oil collected was used in bioassays with larvae and engorged females of the cattle tick Rhipicephalus microplus. Biological assays were performed using the larval packet test (LPT) and adult immersion test. The GC-MS of crambe fruit bio-oil revealed mainly hydrocarbons such as alkanes and alkenes, phenols, and aldehydes. The bio-oil in the LPT exhibited an LC90 of 14.4%. In addition, crambe bio-oil caused female mortality of 91.1% at a concentration of 15% and a high egg-laying inhibition. After ovary dissection of treated females, a significant reduction in gonadosomatic index was observed, indicating that bio-oil interfered in tick oogenesis. Considering these results, it may be concluded that slow pyrolysis of crambe fruit affords a sustainable and eco-friendly product for the control of cattle tick R. microplus.

Ticks are important vector hosts of pathogens which cause human and animal diseases worldwide. Diverse viruses have been discovered in ticks; however, little is known about the ecological factors that affect the tick virome composition and evolution. Herein, we employed RNA sequencing to study the virome diversity of the Haemaphysalis longicornis and Rhipicephalus microplus ticks sampled in Hubei Province in China. Twelve RNA viruses with complete genomes were identified, which belonged to six viral families: Flaviviridae, Matonaviridae, Peribunyaviridae, Nairoviridae, Phenuiviridae, and Rhabdoviridae. These viruses showed great diversity in their genome organization and evolution, four of which were proposed to be novel species. The virome diversity and abundance of R. microplus ticks fed on cattle were evidently high. Further ecological analyses suggested that host species and feeding status may be key factors affecting the tick virome structure. This study described a number of novel viral species and variants from ticks and, more importantly, provided insights into the ecological factors shaping the virome structures of ticks, although it clearly warrants further investigation.

Cattle tick (Rhipicephalus microplus) represents a severe problem causing substantial economic losses, estimated in billions of dollars annually. Currently, chemical acaricides represent the most widely used control method. However, several problems such as resistance have been described. Phage-based vaccines represent a fast and low-cost tool for antigen delivery. In this regard, the objective of the present work was to develop a candidate phage-based vaccine displaying a cattle tick antigen (Bm86-derived Sbm7462 antigen) on the surface of bacteriophage M13. Phage ELISA and dot blotting analysis confirmed the display of the antigen. Vaccine immunogenicity was evaluated using a bovine monocyte-derived dendritic cell-based ex vivo assay and a murine in vivo assay. The ex vivo model showed the maturation of dendritic cells after being pulsed with the phage-based vaccine. The humoral response was confirmed in the in vivo assay. These results demonstrated the capacity of the phage-based vaccine to induce both humoral and cellular immune-specific responses. Importantly, this is the first report describing a control method for cattle ticks using a candidate phage-based vaccine. Further studies to evaluate the immunogenicity in a bovine model are needed. The current approach represents a promising alternative to control cattle tick infestations.

Bovine babesiosis is a disease caused by Babesia spp., a protozoan transmitted by ticks of the Ixodidae family, being a disease of economic importance for cattle in the tropics. In Mozambique it is transmitted by ticks of the species Rhipicephalus microplus, R. decoloratus, R. everts everts, and Hyalomma marginatum rufipes and mainly caused by B. bigemina and B. bovis. The disease is characterized by presenting high rates of morbidity and mortality in countries of tropical and subtropical climates, and is widespread in southern Mozambique, where most livestock is made up of beef cattle imported from neighboring countries. This study aimed to investigate gender, age and geographical origin as risk factors associated with serological prevalence and molecular diagnostic of B. bigemina and B. bovis in beef cattle in the provinces of Maputo, Gaza and Inhambane, southern Mozambique, through indirect enzyme-linked immunosorbent assay (i-ELISA) and polymerase chain reaction (PCR). A total of 809 and 240 blood samples from cattle were randomly collected and analyzed simultaneously by i-ELISA and PCR. The overall prevalence of B. bigemina and B. bovis was 71.8% (n = 581) and 76.6% (n = 620), by i-ELISA and 11.3% (n = 27) and 37.1% (n = 89) by PCR test, respectively. Significant difference in the two infections was observed according to age and geographical origin of the samples. The results of this research provide valuable information on the epidemiology of infection with B. bigemina and B. bovis in beef cattle in the region studied, which can be used by domestic livestock managers in planning future interventions in this disease control programs.