Distribución de las garrapatas exófilas en las principales ecorregiones de Guatemala / Distribution of exophilic ticks in the main ecoregions of Guatemala

Las garrapatas son ectoparásitos hematófagos obligados que actúan como vectores biológicos de diversos patógenos ya que parasitan aves, reptiles y mamíferos. Las enfermedades en las cuales actúan como vectores son la anaplasmosis, piroplasmosis, borreliosis, theileriosis y diversas enfermedades rickettsiales. La presencia de garrapatas es mediada por factores ambientales, geográficos y microclimáticos incluso es influenciada por la abundancia de hospedadores, además de ser estos considerados indicadores filogenéticos, ecológicos y biogeográficos de las especies que parasitan. El objetivo del estudio fue conocer la diversidad de especies de garrapatas exófilas en las principales ecorregiones de Guatemala, con la finalidad de determinar la abundancia y su distribución, así como su potencial vectorial ante agentes patógenos de interés veterinario y zoonótico. Se muestrearon cuatro áreas protegidas que representan las ecorregiones más extensas de Guatemala. Se realizaron tres repeticiones en cada sitio de muestreo utilizando la técnica del bandereo. Las garrapatas colectadas fueron colocadas en frascos con etanol al 90% para su preservación y posterior análisis microscópico. Se observaron las garrapatas colectadas utilizando un estero microscopio y claves morfológicas para su identificación. Los datos fueron resumidos utilizando tablas de frecuencia y estadística descriptiva. Las especies encontradas fueron Ixodes affinis en estadío adulto y larvas del género Rhipicephalus sp. El promedio del índice de abundancia para garrapatas adultas fue de 1.68 y para larvas de 33.51. Las especies encontradas en el presente estudio se consideran vectores de interés en medicina veterinaria. Sin embargo, el género Rhipicephalus sp. puede parasitar al humano y transmitir enfermedades Rickettsiales.

Ticks are obligate hematophagous ectoparasites that act as biological vectors of various pathogens since they parasitize birds, reptiles and mammals. The diseases in which they act as vectors are anaplasmosis, piroplasmosis, borreliosis, theileriosis and various rickettsial diseases. The presence of ticks is mediated by environmental, geographic and microclimatic factors and is even influenced by the abundance of hosts, in addition to these being considered phylogenetic, ecological and biogeographic indicators of the species they parasitize. The objective of the study wasto know the diversity of exophilic tick speciesin the main ecoregions of Guatemala, with the purpose of determining their abundance and distribution, as well as their vector potential against pathogenic agents of veterinary and zoonotic interest. Four protected areas that represent the largest ecoregions of Guatemala were sampled. Three repetitions were carried out at each sampling site using the flagging technique. The collected ticks were placed in jars with 90% ethanol for preservation and subsequent microscopic analysis. The collected ticks were observed using a stereomicroscope and morphological keys for identification. Data were summarized using frequency tables and descriptive statistics. The species found were Ixodes affinis in the adult stage and larvae of the genus Rhificephalus sp. The average abundance index for adult ticks was 1.68 and for larvae was 33.51. The species found in the present study are considered vectors of interest in veterinary medicine. However, the genus Rhipicephalus sp. It can parasitize humans and transmit Rickettsial diseases.

RA92A recombinant protein as immunogen to protect cattle against tick challenge in Brazil and Uganda

In this study, the recombinant gut protein rRa92A produced in Pichia pastoris yeast cells was used to immunize cattle in two experiments, one in Brazil and the other in Uganda. In both experiments, the animals were intramuscularly (IM) injected with 200 µg of recombinant protein in Brazil on days 0, 30 and 51 and in Uganda on days 0, 30. Blood samples for sera separation were collected from different days in both experiments. These samples were analyzed by ELISAs. In Brazil, ticks collected from the animals during the experimental period were analyzed for biological parameters. At Uganda, blood was collected to assess blood parameters, clinical signs were recorded and adult tick (Rhipicephalus appendiculatus) counts were performed. All animals of the vaccinated groups were shown to produce antibodies, and it was not possible to detect an effect on Rhipicephalus microplus. All the clinical parameters were considered within the normal ranges for both the experimental and control groups in Uganda. Antibody absorbance was elevated after each immunization and remained high until the end of the experiments, remaining low in the control animals. The results of stall test carried out in Brazil using R. microplus tick showed efficacy of 21.95%. The rRa92A immunization trial experiments in Uganda showing a decrease of 55.2% in the number of engorged adult ticks, which was statistically significant (p<0.05). Assessment of the immunogenicity of Ra92A produced in the P. pastoris expression system in bovines is reported for the first time, and the protein acted as a concealed antigen.

Hematological, clinical and epidemiological aspects of Hepatozoon canis infection by parasitological detection in dogs from the rural area of Sousa, Paraíba, Brazil / Aspectos hematológicos, clínicos e epidemiológicos da infecção por Hepatozoon canis por detecção parasitológica em cães da zona rural de Sousa, Paraíba, Brasil

Hepatozoonosis is caused by protozoa of the genus Hepatozoon. In dogs, the infection is caused mainly by Hepatozoon canis, and there are a few descriptions of the prevalence of this infection in the Northeast region of Brazil, especially in the semi-arid region. Therefore, we aimed to determine the prevalence of Hepatozoon canis infection in dogs in the rural area of Sousa, Paraíba, Brazil, as well as to determine the possible clinical and epidemiological aspects of this infection. Ninety-eight dogs in the rural zone of the municipality of Sousa that were at least 4 months old were evaluated, regardless of their breed or gender. Clinical examinations were carried out, and samples of systemic and peripheral blood were collected to determine the presence of the parasite in blood smears and carry out hemograms. In addition, epidemiological questionnaires about animal health and food management were completed. The prevalence of H. canis infections in dogs was 8.1% (8/98). There were three main changes in the hematological status: thrombocytopenia, anemia and hyperproteinemia, mainly related to percentage of leukocyte infection 5%, and also to the presence of clinical signs such as mucopurulent secretion, lymphadenomegaly, dry skin, pale mucous membranes, and lean or cachectic body score.(AU)

A hepatozoonose é causada por protozoários do gênero Hepatozoon. Em cães, a infecção ocorre principalmente por Hepatozoon canis, sendo escassas as descrições de prevalências desta infecção na região Nordeste do Brasil, sobretudo no Semiárido. Com isso, o trabalho objetivou determinar a prevalência da infecção por Hepatozoon canis em cães da zona rural do município de Sousa, Paraíba, Brasil, como também determinar possíveis sinais clínicos e aspectos epidemiológicos relacionados à esta infecção. Foram avaliados 98 cães da zona rural do município de Sousa, independentemente da raça ou sexo, com idade superior a quatro meses. Foram realizados exames clínicos e colhidas amostras de sangue sistêmico e periférico para a pesquisa do parasito em esfregaços sanguíneos e hemogramas. Além disso, foram preenchidos questionários epidemiológicos acerca do manejo sanitário e alimentar dos animais. A prevalência de cães positivos para H. canis foi de 8,1% (8/98). Foram observados três principais alterações no quadro hematológico, sendo trombocitopenia, anemia e hiperproteinemia, principalmente relacionadas ao percentual de leucócitos infectados 5%, e também à presença de sinais clínicos, como secreção mucopurulenta, linfadenomegalia, pelos ressecados, mucosas hipocoradas e escore corporal magro ou caquético.(AU)

Susceptibility of field populations of Haematobia irritans to fipronil in Uruguay / Suscetibilidade de populações de campo de Haematobia irritans ao fipronil no Uruguai

Fipronil was registered in Uruguay in 1997, and, since then, it has been used for the control of Haematobia irritans irritans and Rhipicephalus microplus. The susceptibility of H. irritants to this drug has not been evaluated. Therefore, the goal of the present study was to evaluate the resistance of H. irritans to fipronil. Additionally, a survey was carried out with the farmers to evaluate the use of fipronil for H. irritans control in the ranches where the flies came from. For the bioassays, 31 field populations of H. irritans were exposed to 10 concentrations of fipronil (3.2-16.0μg.cm2), and their LC50 values were calculated using probit analysis. A bioassay was performed with horn flies from the susceptible colony maintained at the USDA-ARS Knipling-Bushland U.S. Livestock Insects Research Laboratory for comparison and calculation of resistance ratios (RRs). All 31 field populations surveyed in the study were susceptible to fipronil, with resistance ratios ranging from <0.5 to 2.2. Four populations with RRs >1 did not differ significantly from the susceptible strain. A single population showed an RR >2.2. Overall, the survey shows that fipronil was mostly used for R. microplus control, and in only three ranches, which were free of R. microplus, was fipronil used for horn fly control. Seventeen farmers did not use fipronil at all in the last three years. It is concluded that, in Uruguay, field populations of horn flies remain susceptible to fipronil.(AU)

O fipronil foi registrado no Uruguai em 1997 e, desde então, tem sido utilizado no controle de Haematobia irritans irritans e Rhipicephalus microplus. O objetivo do presente estudo foi avaliar a susceptibilidade de populações de campo de H. irritans ao fipronil. Além disso, foi realizada uma pesquisa para avaliar a utilização de fipronil e as práticas de controle de H. irritans nas fazendas de onde provinham as moscas. Para os bioensaios, 31 populações de campo de H. irritans foram expostas a 10 concentrações de fipronil (3,2-16,0μg.cm2), e seus valores de CL50 foram calculados usando análise probit. Um bioensaio foi realizado com H. irritans da colônia suscetível mantida no USDA-ARS Knipling-Bushland U.S. Livestock Insects Research Laboratory para comparação e cálculo das razões de resistência (RRs). Todas as 31 populações de campo pesquisadas no estudo eram suscetíveis ao fipronil, com taxas de resistência variando de <0,5 à 2,2. Quatro populações com Rrs >1 não diferiram significativamente da cepa suscetível. Uma única população apresentou RR >2,2. No geral, o fipronil tinha sido usado principalmente para o controle de R. microplus, e em apenas três fazendas, que estavam livres de R. microplus, o fipronil era utilizado para o controle da H. irritans. Em 17 fazendas não tinha sido utilizado fipronil nos últimos três anos. Conclui-se que no Uruguai as populações de H. irritans no campo permanecem suscetíveis ao fipronil.(AU)

Susceptibility of field populations of Haematobia irritans to fipronil in Uruguay / Suscetibilidade de populações de campo de Haematobia irritans ao fipronil no Uruguai

Fipronil was registered in Uruguay in 1997, and, since then, it has been used for the control of Haematobia irritans irritans and Rhipicephalus microplus. The susceptibility of H. irritants to this drug has not been evaluated. Therefore, the goal of the present study was to evaluate the resistance of H. irritans to fipronil. Additionally, a survey was carried out with the farmers to evaluate the use of fipronil for H. irritans control in the ranches where the flies came from. For the bioassays, 31 field populations of H. irritans were exposed to 10 concentrations of fipronil (3.2-16.0μg.cm2), and their LC50 values were calculated using probit analysis. A bioassay was performed with horn flies from the susceptible colony maintained at the USDA-ARS Knipling-Bushland U.S. Livestock Insects Research Laboratory for comparison and calculation of resistance ratios (RRs). All 31 field populations surveyed in the study were susceptible to fipronil, with resistance ratios ranging from <0.5 to 2.2. Four populations with RRs >1 did not differ significantly from the susceptible strain. A single population showed an RR >2.2. Overall, the survey shows that fipronil was mostly used for R. microplus control, and in only three ranches, which were free of R. microplus, was fipronil used for horn fly control. Seventeen farmers did not use fipronil at all in the last three years. It is concluded that, in Uruguay, field populations of horn flies remain susceptible to fipronil.(AU)

O fipronil foi registrado no Uruguai em 1997 e, desde então, tem sido utilizado no controle de Haematobia irritans irritans e Rhipicephalus microplus. O objetivo do presente estudo foi avaliar a susceptibilidade de populações de campo de H. irritans ao fipronil. Além disso, foi realizada uma pesquisa para avaliar a utilização de fipronil e as práticas de controle de H. irritans nas fazendas de onde provinham as moscas. Para os bioensaios, 31 populações de campo de H. irritans foram expostas a 10 concentrações de fipronil (3,2-16,0μg.cm2), e seus valores de CL50 foram calculados usando análise probit. Um bioensaio foi realizado com H. irritans da colônia suscetível mantida no USDA-ARS Knipling-Bushland U.S. Livestock Insects Research Laboratory para comparação e cálculo das razões de resistência (RRs). Todas as 31 populações de campo pesquisadas no estudo eram suscetíveis ao fipronil, com taxas de resistência variando de <0,5 à 2,2. Quatro populações com Rrs >1 não diferiram significativamente da cepa suscetível. Uma única população apresentou RR >2,2. No geral, o fipronil tinha sido usado principalmente para o controle de R. microplus, e em apenas três fazendas, que estavam livres de R. microplus, o fipronil era utilizado para o controle da H. irritans. Em 17 fazendas não tinha sido utilizado fipronil nos últimos três anos. Conclui-se que no Uruguai as populações de H. irritans no campo permanecem suscetíveis ao fipronil.(AU)

Intestinal changes and performance parameters in ticks feeding on calves immunized with subunits of immunogens against Rhipicephalus microplus.

We describe the intestinal changes and biological parameters of the tick species Rhipicephalus microplus exposed to the immune response of calves vaccinated with two subunits of immunogens. The first group of Bos taurus calves was immunized with a synthetic peptide (SBm7462), whereas the second group received an inoculum for synthetic control. The third group was immunized with a recombinant peptide (rSBm7462); an inoculum was injected into a fourth group of calves for recombinant control. Each formulation was administered to these calves during three times at intervals of 30 days. At 21 days after the last immunization, the calves were challenged using a total of 4500 larvae per animal. Indirect ELISA was realized to identify the kinetics of IgGs from samples of calves studied. Naturally detaching ticks were collected for analyses of biological performance and histological changes in the midgut. We dissected randomly detached ticks. The midgut of each of these ticks was removed and processed routinely for histology, stained with hematoxylin-eosin (H&E) and slow Giemsa. Slides were also subjected to immunohistochemistry. The antibody response showed significant induction of high-affinity IgGs in calves immunized with both peptides in comparison to calves of the control groups. Histological changes included damage of the intestinal epithelium in ticks fed on immunized hosts and intense immunostaining in midgut cells, using the serum of calves immunized with recombinant peptide. There were significant differences in all biological performing parameters of ticks detached from vaccinated calves in comparison with ticks of the control groups. We identified reductions of 87.7 and 93.5% in engorged ticks detached from calves immunized with a synthetic and recombinant peptides, respectively, a 28 and 8.60% lower egg mass in groups immunized with synthetic and recombinant peptides, respectively, and a 38.4% reduction of the value of nutrient index/tick in the group immunized with the recombinant peptide. Our findings show that the immune response induced by small peptides in cattle can modify the digestion and metabolism of ticks fed on vaccinated animals, resulting in changes in tick performance.

Occurrence of Babesia vogeli, Mycoplasma spp., Ehrlichia canis and Anaplasma spp. in a hospital dog population of western Paraná / Ocorrência de Babesia vogeli, Mycoplasma spp., Ehrlichia canis e Anaplasma spp. em uma população hospitalar de cães do Oeste do Paraná

Ehrlichia canis, Anaplasma platys, and Babesia vogeli are frequently detected in the veterinary routine with varied pathogenesis that can lead to death, mainly in co-infections. Although canine hemotropic mycoplasmas are considered of low clinical importance, they have recently gained prominence in molecular research. The present study aimed to analyze two hospital populations of dogs, randomly selected from the year 2013 and 2015, from the municipalities of Toledo (n=68) and Cascavel (n=107). Direct examination of blood smears, serology, and PCR were used to detect the presence of E. canis, A. platys, B. vogeli and Mycoplasma sp. Direct blood smear examination was negative for the investigated agents in all samples. Serum immunochromatography (SensPERT ™, VetAll Laboratories, Korea) in 175 animals showed that only 4% (n = 7) had anti-E. canis antibodies, while 60% (n = 105) were positive for Anaplasma sp. All PCR samples were negative for E. canis, while 18.28% (n = 32) were positive for A. platys, 3.42% (n = 6) positive for Babesia vogeli, and 7.41% (n = 13) positive for Mycoplasma sp. The study revealed the presence of A. platys in Toledo and Cascavel by PCR, which accentuates the need to monitor vector populations and usual hosts and to evaluate the potential risk of infection in humans.

Ehrlichia canis, Anaplasma platys e Babesia vogeli são frequentemente detectados na rotina veterinária com patogênese variada que pode levar à morte, principalmente em coinfecções. Embora os micoplasmas hemotrópicos caninos sejam considerados de baixa importância clínica, recentemente ganharam destaque na pesquisa molecular. O presente estudo teve como objetivo analisar duas populações hospitalares de cães, selecionadas aleatoriamente no ano de 2013 e 2015, dos municípios de Toledo (n = 68) e Cascavel (n = 107). O exame direto de esfregaços de sangue, sorologia e PCR foram usados para detectar a presença de E. canis, A. platys, B. vogeli e Mycoplasma sp. O esfregaço sanguíneo direto foi negativo para os agentes investigados em todas as amostras. A imunocromatografia sérica (SensPERT ™, VetAll Laboratories, Coréia) em 175 animais mostrou que apenas 4% (n = 7) tinham anticorpos contra E.canis, enquanto 60% (n = 105) foram positivos para Anaplasma sp. Todas as amostras de PCR foram negativas para E. canis, enquanto 18,28% (n = 32) foram positivas para A. platys, 3,42% (n = 6) positivas para Babesia vogeli e 7,41% (n = 13) positivas para Mycoplasma sp. O estudo revelou a presença de A. platys em Toledo e Cascavel por PCR, o que acentua a necessidade de monitorar populações de vetores e hospedeiros usuais e avaliar o risco potencial de infecção em humanos.

Occurrence of Babesia vogeli, Mycoplasma spp., Ehrlichia canis and Anaplasma spp. in a hospital dog population of western Paraná / Ocorrência de Babesia vogeli, Mycoplasma spp., Ehrlichia canis e Anaplasma spp. em uma população hospitalar de cães do Oeste do Paraná

Ehrlichia canis, Anaplasma platys, and Babesia vogeli are frequently detected in the veterinary routine with varied pathogenesis that can lead to death, mainly in co-infections. Although canine hemotropic mycoplasmas are considered of low clinical importance, they have recently gained prominence in molecular research. The present study aimed to analyze two hospital populations of dogs, randomly selected from the year 2013 and 2015, from the municipalities of Toledo (n=68) and Cascavel (n=107). Direct examination of blood smears, serology, and PCR were used to detect the presence of E. canis, A. platys, B. vogeli and Mycoplasma sp. Direct blood smear examination was negative for the investigated agents in all samples. Serum immunochromatography (SensPERT ™, VetAll Laboratories, Korea) in 175 animals showed that only 4% (n = 7) had anti-E. canis antibodies, while 60% (n = 105) were positive for Anaplasma sp. All PCR samples were negative for E. canis, while 18.28% (n = 32) were positive for A. platys, 3.42% (n = 6) positive for Babesia vogeli, and 7.41% (n = 13) positive for Mycoplasma sp. The study revealed the presence of A. platys in Toledo and Cascavel by PCR, which accentuates the need to monitor vector populations and usual hosts and to evaluate the potential risk of infection in humans.(AU)

Ehrlichia canis, Anaplasma platys e Babesia vogeli são frequentemente detectados na rotina veterinária com patogênese variada que pode levar à morte, principalmente em coinfecções. Embora os micoplasmas hemotrópicos caninos sejam considerados de baixa importância clínica, recentemente ganharam destaque na pesquisa molecular. O presente estudo teve como objetivo analisar duas populações hospitalares de cães, selecionadas aleatoriamente no ano de 2013 e 2015, dos municípios de Toledo (n = 68) e Cascavel (n = 107). O exame direto de esfregaços de sangue, sorologia e PCR foram usados para detectar a presença de E. canis, A. platys, B. vogeli e Mycoplasma sp. O esfregaço sanguíneo direto foi negativo para os agentes investigados em todas as amostras. A imunocromatografia sérica (SensPERT ™, VetAll Laboratories, Coréia) em 175 animais mostrou que apenas 4% (n = 7) tinham anticorpos contra E.canis, enquanto 60% (n = 105) foram positivos para Anaplasma sp. Todas as amostras de PCR foram negativas para E. canis, enquanto 18,28% (n = 32) foram positivas para A. platys, 3,42% (n = 6) positivas para Babesia vogeli e 7,41% (n = 13) positivas para Mycoplasma sp. O estudo revelou a presença de A. platys em Toledo e Cascavel por PCR, o que acentua a necessidade de monitorar populações de vetores e hospedeiros usuais e avaliar o risco potencial de infecção em humanos.(AU)

Pyrethroid Acaricide Resistance Is Proportional to P-450 Cytochrome Oxidase Expression in the Cattle Tick Rhipicephalus microplus.

The goal of the present study was to assess the gene expression of xenobiotic metabolizing enzymes (XMEs) Cytochrome P-450 (CYP) and carboxylesterase (CE) related to detoxification of synthetic pyrethroids, plus acetylcholinesterase (AChE), in field isolates of acaricide-resistant Rhipicephalus microplus. The XMEs expression levels were assessed by mRNA measurement using quantitative reverse transcription PCR. The XME expression levels of field-isolated acaricide-resistant ticks were compared against acaricide-susceptible reference ticks used in this study as a gene expression baseline and represented as relative expression units (REU). Field isolates were subjected to toxicological bioassays and determined resistant to all the Pyr acaricides (Pyr), whereas most of them were found susceptible to organophosphorous acaricides (OP), with the exception of three isolates, which exhibited moderate resistance to Diazinon. Significantly higher levels of CYP were detected in pyrethroid-resistance ticks when compared to Su ticks (P<0.01). A linear regression analysis showed that pyrethroid acaricide resistance levels of R. microplus were proportional to the CYP expression levels (correlation coefficient (R):0.85; P<0.05). Analysis on CE expression levels showed only one isolate resistant to Pyr and OP with a statistically significant increase (P<0.01). AChE expression levels showed statistically significant (P<0.01) subexpression in all tick isolates when compared to the susceptible reference. Our results suggest that pyrethroid acaricide resistance in the cattle tick may be diagnosed by measuring the CYP expression levels using quantitative PCR.

Molecular characterization of the recombinant protein RmLTI-BmCG-LTB: Protective immunity against Rhipicephalus (Boophilus) microplus.

The bovine tick Rhipicephalus (Boophilus) microplus is found in several tropical and subtropical regions of the world. This parasite transmits pathogens that cause disease, such as babesiosis (Babesia bovis and B. bigemina) and anaplasmosis (Anaplasma marginale). Tick infestations cause enormous livestock losses, and controlling tick infestations and the transmission of tick-borne diseases remains a challenge for the livestock industry. Because the currently available commercial vaccines offer only partial protection against R. (B.) microplus, there is a need for more efficient vaccines. Several recombinant antigens have been evaluated using different immunization strategies, and they show great promise. This work describes the construction and immunological characterization of a multi-antigen chimera composed of two R. (B.) microplus antigens (RmLTI and BmCG) and one Escherichia coli antigen (B subunit, LTB). The immunogenic regions of each antigen were selected and combined to encode a single polypeptide. The gene was cloned and expressed in E. coli. For all of the experiments, two groups (treated and control) of four Angus heifers (3-6 months old) were used. The inoculation was performed via intramuscular injection with 200 µg of purified recombinant chimeric protein and adjuvated. The chimeric protein was recognized by specific antibodies against each subunit and by sera from cattle inoculated with the chimera. Immunization of RmLTI-BmCG-LTB cattle reduced the number of adult female ticks by 6.29% and vaccination of cattle with the chimeric antigen provided 55.6% efficacy against R. (B.) microplus infestation. The results of this study indicate that the novel chimeric protein is a potential candidate for the future development of a more effective vaccine against R. (B.) microplus.

Phytochemical analysis and acaricidal activity of Aloe arborescens Mill. extracts against Rhipicephalus (Boophilus) microplus / Análise fitoquímica e atividade acaricida de extratos de Aloe arborescens Mill. sobre Rhipicephalus (Boophilus) microplus

The indiscriminate use of chemical acaricides has allowed Rhipicephalus (Boophilus) microplus to develop resistance to several active principles. However, botanical extracts have been tested as an alternative method to control those ticks. This experiment studied the chemical fingerprint and acaricidal effect of fresh and dry Aloe arborescens Mill. extracts on R. (B.) microplus. The acaricidal activity of extracts was assessed using in vitro assays with engorged females, and phytochemical characterization was performed by infrared (IR) spectroscopy and high-performance liquid chromatography (HPLC). The results showed that fresh and dry A. arborescens extracts prepared with the solvents pure ethanol, ethanol-dichloromethane binary mixture, and ethanol-dichloromethane-acetone ternary mixture, contained water-soluble tannins and had a strong effect on the reproductive parameters of R. (B.) microplus demonstrated by a marked decreased in the number of eggs laid and in the larvae hatching rate (p 0.05, p 0.01, p 0.001). In conclusion, A. arborescens Mill. has components with acaricidal activity against R. (B.) microplus, and phytotherapy with extracts of this plant may be used as an alternative method of R. (B.) microplus control.(AU)

O uso indiscriminado de acaricidas químicos permitiu o desenvolvimento de resistência de Rhipicephalus (Boophilus) microplus a vários princípios ativos. Entretanto, extratos botânicos têm sido testados como método alternativo para o controle desses carrapatos. Este experimento foi conduzido para estudar a impressão digital química e o efeito acaricida de extratos frescos e desidratados de Aloe arborescens Mill sobre R. (B.) microplus. A atividade acaricida dos extratos foi avaliada por meio de testes in vitro com fêmeas ingurgitadas e a caracterização fitoquímica foi determinada por espectroscopia no infravermelho (IV) e cromatografia líquida de alta eficiência (HPLC). Os resultados demostraram que os extratos frescos e desidratados de A. arborescens Mill obtidos com os solventes etanol puro, mistura binária de etanol e diclorometano, e mistura ternária de etanol, diclorometano e acetona, continham taninos hidrossolúveis e apresentaram maior atividade acaricida sobre os parâmetros reprodutivos de R. (B.) microplus, pois observou-se queda acentuada no número de ovos postos e na taxa de eclosão das larvas (p 0,05; p 0,01; p 0,001). Conclui-se que A. arborescens Mill possui componentes com efeito acaricida contra R. (B.) microplus e que a fitoterapia, com os extratos dessa planta, pode ser utilizada como método alternativo para o controle de R. (B.) microplus.(AU)

Acaricidal activity of Havardia albicans and Caesalpinia gaumeri methanolic leaf extracts on Rhipicephalus microplus and its toxicity to laboratory animals.

The acaricidal activity of methanolic extracts from the leaves of Havardia albicans (Kunth Britton and Rose) and Caesalpinia gaumeri (Greenm) were tested on the larvae and adults of the cattle tick Rhipicephalus microplus Canestrini using the larval immersion test and the adult immersion test, respectively. The toxicity of these extracts was also evaluated on laboratory animals using toxicity bioassays at different concentrations: skin irritability (500 mg/ml), acute oral toxicity (5000 mg/kg), ocular irritability (1000 mg/ml) and dermal toxicity (5000 mg/kg). The acaricidal activity of the H. albicans extracts on R. microplus larvae showed a LC50 of 7.0% (4.3-11.4) and a LC99 of 25.5% (14.26-201.5). The acaricidal activity of the C. gaumeri extracts on larvae showed a LC50 of 7.8% (5.74-10.65) and a LC99 of 38.32% (22.22-146.48). The H. albicans extracts showed moderate acaricidal activity in the inhibition of egg laying (54.4 ± 12.4) and the inhibition of larval hatching (48.7 ± 6.8) in R. microplus adults. The C. gaumeri extracts also showed moderate acaricidal activity in the inhibition of egg laying (51.0 ± 11.2). However, none of the evaluated extracts showed significant toxicity on laboratory rodents. These plants show the potential to control R. microplus and could be administered topically or orally in animals. Further studies are needed to identify the active compound(s) and to evaluate the effects of these plants on R. microplus in vivo.

Phytochemical analysis and acaricidal activity of Aloe arborescens Mill. extracts against Rhipicephalus (Boophilus) microplus / Análise fitoquímica e atividade acaricida de extratos de Aloe arborescens Mill. sobre Rhipicephalus (Boophilus) microplus

The indiscriminate use of chemical acaricides has allowed Rhipicephalus (Boophilus) microplus to develop resistance to several active principles. However, botanical extracts have been tested as an alternative method to control those ticks. This experiment studied the chemical fingerprint and acaricidal effect of fresh and dry Aloe arborescens Mill. extracts on R. (B.) microplus. The acaricidal activity of extracts was assessed using in vitro assays with engorged females, and phytochemical characterization was performed by infrared (IR) spectroscopy and high-performance liquid chromatography (HPLC). The results showed that fresh and dry A. arborescens extracts prepared with the solvents pure ethanol, ethanol-dichloromethane binary mixture, and ethanol-dichloromethane-acetone ternary mixture, contained water-soluble tannins and had a strong effect on the reproductive parameters of R. (B.) microplus demonstrated by a marked decreased in the number of eggs laid and in the larvae hatching rate (p 0.05, p 0.01, p 0.001). In conclusion, A. arborescens Mill. has components with acaricidal activity against R. (B.) microplus, and phytotherapy with extracts of this plant may be used as an alternative method of R. (B.) microplus control.

O uso indiscriminado de acaricidas químicos permitiu o desenvolvimento de resistência de Rhipicephalus (Boophilus) microplus a vários princípios ativos. Entretanto, extratos botânicos têm sido testados como método alternativo para o controle desses carrapatos. Este experimento foi conduzido para estudar a impressão digital química e o efeito acaricida de extratos frescos e desidratados de Aloe arborescens Mill sobre R. (B.) microplus. A atividade acaricida dos extratos foi avaliada por meio de testes in vitro com fêmeas ingurgitadas e a caracterização fitoquímica foi determinada por espectroscopia no infravermelho (IV) e cromatografia líquida de alta eficiência (HPLC). Os resultados demostraram que os extratos frescos e desidratados de A. arborescens Mill obtidos com os solventes etanol puro, mistura binária de etanol e diclorometano, e mistura ternária de etanol, diclorometano e acetona, continham taninos hidrossolúveis e apresentaram maior atividade acaricida sobre os parâmetros reprodutivos de R. (B.) microplus, pois observou-se queda acentuada no número de ovos postos e na taxa de eclosão das larvas (p 0,05; p 0,01; p 0,001). Conclui-se que A. arborescens Mill possui componentes com efeito acaricida contra R. (B.) microplus e que a fitoterapia, com os extratos dessa planta, pode ser utilizada como método alternativo para o controle de R. (B.) microplus.

Risk factors related to resistance to Rhipicephalus (Boophilus) microplus and weight gain of heifers / Fatores de risco relacionados à resistência a Rhipicephalus (Boophilus) microplus e ganho de peso de bezerras

The aim of the present study was to evaluate the influence of age and genetics in dairy heifers on resistance to the cattle tick Rhipicephalus (Boophilus) microplus and correlate these parameters with weight gain. Twenty-two heifers were evaluated from birth up to two years of age. Resistance to the cattle tick was evaluated by counting the number of engorged female ticks and subjective qualification of the larvae and nymph infestation. The animals were weighted in the first 24 hours after birth and at six, 12, 18 and 24 months of age. The average tick count and weight gain were compared by Tukeys test at 5% significance. Subsequently, linear regression was performed to verify the strength of the association between the risk factors age and genetics and infestation by R. (B.) microplus. Age and genetics were both significant risk factors for R. (B.) microplus infestation in heifers. Between the third and sixth months of age, the animals showed a window of susceptibility to R. (B.) microplus. Regardless of age, Bos taurus heifers had higher infestations than Bos indicus, crossbred F1 (½ B. taurus x ½ B. indicus) and crossbred Gir-Holstein (Girolando) (5/8 B. taurus x 3/8 B. indicus) heifers. B. taurus heifers were heavier than B. indicus heifers at birth and had significantly greater weight gain (p 0.01).(AU)

O objetivo do estudo foi conhecer a influência da idade e da genética sobre a resistência ao carrapato Rhipicephalus (Boophilus) microplus e correlacionar estes parâmetros com ganho de peso de bezerras de origem leiteira. Foram avaliadas 22 bezerras desde o nascimento até dois anos de idade. A avaliação da resistência foi realizada por meio da contagem de teleóginas ingurgitados e qualificação subjetiva da infestação por larvas e ninfas. Os animais foram pesados nas primeiras 24 horas pós-nascimento, aos seis, 12, 18 e 24 meses de idade. A comparação das médias das contagens de carrapatos e ganho de peso foi realizada pelo teste Tukey a 5% de significância. Posteriormente foi realizada regressão linear para verificar a força da associação entre os fatores de risco idade e genética e a infestação por R. (B.) microplus. A idade e a genética constituíram importantes fatores de risco para infestação por R. (B.) microplus nas bezerras. Entre o terceiro e sexto mês de idade, os animais apresentaram uma janela de suscetibilidade ao carrapato R. (B.) microplus. Independente da idade, bezerras Bos taurus foram mais infestadas do que bezerras Bos indicus, mestiças F1 (½ B. taurus x ½ B. indicus) e Girolandas (5/8 B. taurus x 3/8 B. indicus). Além de nascerem mais pesadas, as bezerras B. taurus demonstraram ganho de peso significativamente maior (p 0.01) do que as bezerras B. indicus.(AU)

Risk factors related to resistance to Rhipicephalus (Boophilus) microplus and weight gain of heifers / Fatores de risco relacionados à resistência a Rhipicephalus (Boophilus) microplus e ganho de peso de bezerras

The aim of the present study was to evaluate the influence of age and genetics in dairy heifers on resistance to the cattle tick Rhipicephalus (Boophilus) microplus and correlate these parameters with weight gain. Twenty-two heifers were evaluated from birth up to two years of age. Resistance to the cattle tick was evaluated by counting the number of engorged female ticks and subjective qualification of the larvae and nymph infestation. The animals were weighted in the first 24 hours after birth and at six, 12, 18 and 24 months of age. The average tick count and weight gain were compared by Tukeys test at 5% significance. Subsequently, linear regression was performed to verify the strength of the association between the risk factors age and genetics and infestation by R. (B.) microplus. Age and genetics were both significant risk factors for R. (B.) microplus infestation in heifers. Between the third and sixth months of age, the animals showed a window of susceptibility to R. (B.) microplus. Regardless of age, Bos taurus heifers had higher infestations than Bos indicus, crossbred F1 (½ B. taurus x ½ B. indicus) and crossbred Gir-Holstein (Girolando) (5/8 B. taurus x 3/8 B. indicus) heifers. B. taurus heifers were heavier than B. indicus heifers at birth and had significantly greater weight gain (p 0.01).

O objetivo do estudo foi conhecer a influência da idade e da genética sobre a resistência ao carrapato Rhipicephalus (Boophilus) microplus e correlacionar estes parâmetros com ganho de peso de bezerras de origem leiteira. Foram avaliadas 22 bezerras desde o nascimento até dois anos de idade. A avaliação da resistência foi realizada por meio da contagem de teleóginas ingurgitados e qualificação subjetiva da infestação por larvas e ninfas. Os animais foram pesados nas primeiras 24 horas pós-nascimento, aos seis, 12, 18 e 24 meses de idade. A comparação das médias das contagens de carrapatos e ganho de peso foi realizada pelo teste Tukey a 5% de significância. Posteriormente foi realizada regressão linear para verificar a força da associação entre os fatores de risco idade e genética e a infestação por R. (B.) microplus. A idade e a genética constituíram importantes fatores de risco para infestação por R. (B.) microplus nas bezerras. Entre o terceiro e sexto mês de idade, os animais apresentaram uma janela de suscetibilidade ao carrapato R. (B.) microplus. Independente da idade, bezerras Bos taurus foram mais infestadas do que bezerras Bos indicus, mestiças F1 (½ B. taurus x ½ B. indicus) e Girolandas (5/8 B. taurus x 3/8 B. indicus). Além de nascerem mais pesadas, as bezerras B. taurus demonstraram ganho de peso significativamente maior (p 0.01) do que as bezerras B. indicus.

3ß-O-tigloylmelianol from Guarea kunthiana: a new potential agent to control Rhipicephalus (Boophilus) microplus, a cattle tick of veterinary significance.

Chemical investigation of Guarea kunthiana fruits, guided by their effect on the reproductive cycle of engorged females of the cattle tick Rhipicephalus (Boophilus) microplus-a major economic problem to the livestock industry worldwide-led to isolation of 3ß-O-tigloylmelianol, a new protolimonoid, from the bioactive hexane phase obtained by partitioning the crude ethanol extract. An adult immersion test was performed. The compound strongly inhibited egg-laying and hatchability (99.2% effectiveness at a 0.01% concentration). Melianone, isolated from the same phase, yielded unremarkable results in the adult immersion test. From the dichloromethane phase, melianol, melianodiol, meliantriol, and a new protolimonoid, 3ß-O-tigloylmeliantriol, were isolated, all of which, in the same manner as melianone, exhibited unremarkable results in the test. The structures of new and known compounds were mostly established by 1D- and 2D-NMR analyses and mass spectrometry data. This is the first report on the bioactivity of protolimonoids on the reproductive cycle of engorged females of R. (B.) microplus. 3ß-O-Tigloylmelianol proved a promising candidate for the development of a biocontrol agent against the cattle tick investigated, as an alternative to environmentally hazardous synthetic acaricides.

Expression of immune response genes in peripheral blood of cattle infested with Rhipicephalus microplus.

The bovine tick Rhipicephalus microplus is responsible for severe economic losses in tropical cattle production. Bos indicus breeds are more resistant to tick infestations than are Bos taurus breeds, and the understanding of the physiological mechanisms involved in this difference is important for the development of new methods of parasite control. We evaluated differences in the transcript expression of genes related to the immune response in the peripheral blood of cattle previously characterized as resistant or susceptible to tick infestation. Crossbreed F2 Gir x Holstein animals (resistant, N = 6; susceptible, N = 6) were artificially submitted to tick infestation. Blood samples were collected at 0, 24, and 48 h after tick infestation and evaluated for transcript expression of the CD25, CXCL8, CXCL10, FoxP3, interleukin (IL)-10, and tumor necrosis factor alpha (TNFα) genes. Gene expression of CD25 (6.00, P < 0.01), IL-10 (31.62, P < 0.01), FoxP3 (35.48, P < 0.01), and CXCL10 (3.38, P < 0.05) was altered in the resistant group at 48 h compared with samples collected before infestation. In the susceptible group, CXCL8 (-2.02, P < 0.05) and CXCL10 (2.20, P < 0.05) showed altered expression 24 h after infestation. CXCL8 (-5.78, P < 0.05) also showed altered expression at 48 h after infestation when compared with samples collected before infestation. We detected a correlation between T γδ cell activity and the immunological mechanisms that result in a higher resistance to R. microplus in cattle.

Resistência contra ectoparasitas em bovinos da raça Crioula Lageana e meio-sangue Angus avaliada em condições naturais / Resistence against ectoparasites in CriouloLageano and crossbred Angus cattle in southern Brazil under natural conditions

Este trabalho foi desenvolvido com o objetivo de avaliar a resistência aos ectoparasitas em bovinos jovens da raça Crioula Lageana e meio-sangue Angus em condições naturais. Foram utilizados 10 machos castrados em cada grupo, recém desmamados (6-8 meses) e mantidos sob as mesmas condições de manejo, em pastagens cultivadas de inverno e verão, no município de Monte Castelo - SC, sofrendo infestação natural por ectoparasitas. A cada 28 dias, fêmeas de carrapatos (Rhipicephalus (Boophilus) microplus) com tamanho acima de 4 mm foram quantificadas nos dois lados do corpo de cada animal, bem como os nódulos com larvas de Dermatobia hominis. A espessura da capa do pelame foi também avaliada a cada coleta e os animais foram classificados quanto à coloração do pelame. Os animais da raça Crioula Lageana foram mais resistentes às infestações por D. hominis e R. microplus. Não houve diferença entre a disposição de carrapatos e bernes conforme os lados direito e esquerdo dos animais. Os animais de pelagem escura albergaram a maior porcentagem de ectoparasitas nos grupos avaliados.(AU)

This study was carried out to evaluate the breed resistance against ectoparasites infestations in Crioula Lageana and crossbred Angus male calves under natural condition. Ten weaned and neutered male calves (6-8 months) of each group were kept together in winter and summer pastures in Monte Castelo, Santa Catarina State. Every 28 days, female ticks (Rhipicephalus (Boophilus) microplus) more than 4 mm long were counted on the right and left side of the body of each animal, as well as the D. hominis nodules. Coat thickness also was measured at each sampling and all animals were classified according coat color. Crioula Lageana group was less infested by D. hominis than crossbred Angus in five times and by ticks in the infestation peak (P<0.05). There were no differences in the distribution of the ticks and grubs between animal body sides. Dark-haired animal in both groups were the most susceptible.(AU)

Resistência contra ectoparasitas em bovinos da raça Crioula Lageana e meio-sangue Angus avaliada em condições naturais / Resistence against ectoparasites in CriouloLageano and crossbred Angus cattle in southern Brazil under natural conditions

Este trabalho foi desenvolvido com o objetivo de avaliar a resistência aos ectoparasitas em bovinos jovens da raça Crioula Lageana e meio-sangue Angus em condições naturais. Foram utilizados 10 machos castrados em cada grupo, recém desmamados (6-8 meses) e mantidos sob as mesmas condições de manejo, em pastagens cultivadas de inverno e verão, no município de Monte Castelo - SC, sofrendo infestação natural por ectoparasitas. A cada 28 dias, fêmeas de carrapatos (Rhipicephalus (Boophilus) microplus) com tamanho acima de 4 mm foram quantificadas nos dois lados do corpo de cada animal, bem como os nódulos com larvas de Dermatobia hominis. A espessura da capa do pelame foi também avaliada a cada coleta e os animais foram classificados quanto à coloração do pelame. Os animais da raça Crioula Lageana foram mais resistentes às infestações por D. hominis e R. microplus. Não houve diferença entre a disposição de carrapatos e bernes conforme os lados direito e esquerdo dos animais. Os animais de pelagem escura albergaram a maior porcentagem de ectoparasitas nos grupos avaliados.

This study was carried out to evaluate the breed resistance against ectoparasites infestations in Crioula Lageana and crossbred Angus male calves under natural condition. Ten weaned and neutered male calves (6-8 months) of each group were kept together in winter and summer pastures in Monte Castelo, Santa Catarina State. Every 28 days, female ticks (Rhipicephalus (Boophilus) microplus) more than 4 mm long were counted on the right and left side of the body of each animal, as well as the D. hominis nodules. Coat thickness also was measured at each sampling and all animals were classified according coat color. Crioula Lageana group was less infested by D. hominis than crossbred Angus in five times and by ticks in the infestation peak (P<0.05). There were no differences in the distribution of the ticks and grubs between animal body sides. Dark-haired animal in both groups were the most susceptible.

Seleção de isolados de Metarhizium anisopliae s.i. para o controle biológico de Rhipicephalus microplus a partir da caracterização morfológica e molecular e testes de patogenicidade

Na tentativa de diminuir a utilização de produtos químicos e os danos por eles causados, novas alternativas para o controle de carrapatos vem sendo estudadas. O fungo Metarhizium anisopliae é um dos mais estudados em programas agropecuários de manejo de pragas, pois apresenta grande potencial acaricida. Baseado nisso, o presente estudo objetivou a caracterização morfológica, molecular e a avaliação da virulência de 30 isolados brasileiros de M. anisopliae s.l. provenientes de diferentes regiões geográficas, hospedeiros ou substratos, com a finalidade de selecionar isolados mais virulentos para utilização em futuros programas de biocontrole de carrapatos. Inicialmente os isolados foram caracterizados morfologicamente para confirmação de sua identificação, também sendo avaliado o potencial de produção de conídios de cada isolado. As colônias estudadas apresentaram características morfológicas compatíveis com as descritas na literatura. O tamanho das colônias variou entre 29,66 mm e 51,33 mm de diâmetro. Houve variação no comprimento e na largura de conídios e fiálides num mesmo isolado, assim como a presença de fiálides agrupadas e solitárias. O potencial de produção de conídios foi variável entre os isolados, porém tanto o tamanho dos conídios quanto o diâmetro das colônias não influenciaram a produção de conídios. Numa segunda etapa do estudo, foi avaliada a virulência destes isolados sobre larvas de Rhipicephalus microplus tratadas com uma das quatro diferentes concentrações de conídios (105, 106, 107 ou 108 conídios/mL). Foi confirmada a ação letal dos isolados brasileiros de M. anisopliae s.l. sobre larvas de R. microplus, geralmente ocorrendo de forma diretamente proporcional a concentração conidial dos tratamentos. A maioria dos isolados ocasionou a morte de metade da população de larvas com a concentração de 107 conídios/mL; os isolados mais virulentos apresentaram esta concentração letal com 106 conídios/mL, com percentuais médios de mortalidade de larvas próximos de 100% ao 20º dia após tratamento. Além disso, buscou-se avaliar a variabilidade genética destes isolados e sua relação com outras espécies do gênero Metarhizium através da análise de RFLP-PCR e do sequenciamento da região ITS1-5.8S-ITS2 do rDNA. Não foi observado um padrão de especificidade para o agrupamento entre isolados oriundos de mesma região, hospedeiro ou substrato. Foi observada variabilidade genética entre os isolados que basicamente se agruparam em dois grupos. O isolado CG 344 mostrou-se geneticamente distante de todos os outros, mas de acordo com a comparação com sequências obtidas do “GenBank” mostrou-se relacionado ao gênero Metarhizium. Esta variação pode ser devido ao fato deste isolado ter sido poupado de processos que gerassem alterações morfológicas e moleculares, o que possivelmente contribuiu para a pequena variabilidade genética obsevada. O presente estudo possibilitou a detecção de isolados brasileiros de M. anisopliae s.l. com elevada virulência para larvas de R. microplus, podendo ser considerados potenciais agentes no biocontrole desta espécie de carrapato, ressaltando a importância da utilização de ferramentas moleculares para identificação e caracterização destes isolados, contribuindo para a qualidade do produto, o sucesso de sua aplicação e o monitoramento de um isolado introduzido no ambiente com finalidade de controle biológico