Density and behavior of capybara (Hydrochoerus hydrochaeris) ticks (Acari: Ixodidae) Amblyomma sculptum and Amblyomma dubitatum with notes on Rickettsia bellii infection: Assessing human exposure risk.

In several urban and peri­urban areas of Brazil, populations of Amblyomma sculptum and Amblyomma dubitatum ticks are maintained by capybaras (Hydrochoerus hydrochaeris). In some of these areas, this host and these tick species are associated with Brazilian spotted fever (BSF), a lethal human disease caused by the bacterium Rickettsia rickettsii. In this work, we evaluated the risk of human exposure to these tick species using four collection techniques to discern host-seeking behavior. The study was carried out in 10 urban sites inhabited by capybaras in Uberlândia, a BSF-free municipality in southeastern Brazil. Ticks were collected in areas of 400 m2 at each site and at three seasons. Within the same municipality, the distance and speed of A. sculptum nymphs moving towards the CO2 traps were evaluated. In a sample of ticks Rickettsia DNA was investigated. During the study period, 52,953 ticks were collected. Among these, 83.4 % were A. sculptum (1,523 adults, 10,545 nymphs and 32,104 larvae) and 16.6 % were A. dubitatum (464 adults, 2,153 nymphs and 6,164 larvae). An average annual questing tick density of 4.4/m² was observed, with the highest density recorded at one site in autumn (31.8/m²) and the lowest in summer at another site (0.03/m²). The visual search yielded the highest proportion of A. sculptum larvae, constituting 47 % of the total and 63.6 % of all A. sculptum larvae. In contrast, CO2 traps collected a greater proportion of nymphs and adults of A. sculptum ticks. In the case of A. dubitatum, the CO2 trap was the most efficient technique with 57.7 % of captures of this species, especially of nymphs (94.5 % of captures) and adults (97.8 % of captures). Ticks' ambush height on vegetation (9 to 77 cm), observed by visual search 30 times, yielded a total of 20,771 ticks. Of these, 28 (93 %) were A. sculptum ticks, with only two (7 %) identified as A. dubitatum ticks. Among A. sculptum ticks, the nymph was the most attracted stage to humans and larva in the case of A. dubitatum. Amblyomma sculptum adults and nymphs were significantly more attracted to humans than those of A. dubitatum, but A. dubitatum larvae were significantly more attracted than the same stage of A. sculptum. The maximum distance and speed of horizontal displacement for A. sculptum nymphs were five meters and 2.0 m/h, respectively. The only species of Rickettsia detected in ticks, exclusively in A. dubitatum, was R. bellii. Importantly, it was observed that the higher the proportion of A. sculptum in the community of ticks, the lower the rate of infection of A. dubitatum by R. bellii. In conclusion, host-seeking behavior differed between the two tick species, as well as between stages of the same species. A greater restriction of A. dubitatum ticks to the soil was observed, while larvae and nymphs of A. sculptum dispersed higher in the vegetation. The behavior presented by A. sculptum provides greater opportunities for contact with the hosts, while A. dubitatum depends more on an active search for a host, the hunter behavior. Taken together, these observations show that a human being crossing an area infested with A. sculptum and A. dubitatum ticks will have almost exclusive contact with A. sculptum larvae and/or nymphs. Humans in a stationary position (sitting, lying or immobile) are exposed to both tick species, but they are more attractive to adults and mainly nymphs of A. sculptum compared to the corresponding stages of the tick A. dubitatum. The negative effect of A. sculptum on A. dubitatum infection by R. bellii deserves further studies.

Survey of Rickettsia spp. in ticks (Acari: Ixodidae) infesting opossums (Didelphis albiventris) and capybaras (Hydrochoerus hydrochaeris) from an urban park in southeastern Brazil.

Ticks are hematophagous arthropods and, during feeding, may transmit pathogens to vertebrate hosts, including humans. This study aimed to investigate the presence of Rickettsia spp. in ticks collected between 2010 and 2013 from free-ranging capybaras (Hydrochoerus hydrochaeris) and opossums (Didelphis albiventris) that inhabit Sabiá Park in Uberlândia, Brazil. Overall, 1,860 ticks were collected: 1,272 (68.4%) from capybaras (487 of the species Amblyomma sculptum, 475 adults and 12 nymphs; 778 Amblyomma dubitatum, 727 adults and 51 nymphs; and seven larva clusters of the genus Amblyomma); and 588 (31.6%) from opossums (21 A. sculptum, one adult and 20 nymphs; 79 A. dubitatum, all nymphs; 15 Ixodes loricatus, 12 adults and three nymphs; 457 Amblyomma sp. larva clusters; 15 Ixodes sp. larva clusters; and one Argasidae larva cluster). Out of 201 DNA samples tested for the presence of Rickettsia spp. DNA using polymerase chain reaction (PCR) 12 showed amplification of a gtlA gene segment that was specific to Rickettsia bellii, a bacterium non-pathogenic to humans. As there has been a report showing serological evidence of infections caused by Rickettsia species of the spotted fever group (SFG) in capybaras and opossums in the park, including Rickettsia rickettsii, the etiological agent of Brazilian spotted fever, and considering the presence of A. sculptum ticks, which are aggressive to humans, as well as these vertebrate hosts, which are amplifiers of R. rickettsii, it is important to monitor the presence of SFG rickettsiae in the Sabiá Park, which is visited daily by thousands of people.

Molecular detection of Borrelia sp. in Ornithodoros cavernicolous (Acari: Argasidae) in midwestern Brazil.

Ticks are obligate hematophagous parasites that can transmit to vertebrate hosts several pathogens, including viruses, bacteria, protozoa and helminths. Among these agents, some Borrelia species some Borrelia species cause disease in humans and other vertebrate hosts; therefore, they have medical and veterinary health importance. To gather additional information on Borrelia species in Brazil, the current study aimed to detect the presence of these species in Ornithodoros cavernicolous ticks collected in September 2019 from cement pipes that are used by bats as shelter in a farm located in the midwestern region of Brazil. DNA samples obtained from 18 specimens of O. cavernicolous were subjected of two polymerase chain reactions, targeting a segment of the Borrelia fla B gene. Of the samples tested, only one (6 %, 1/18) showed amplification. The nucleotide sequence of the amplified DNA showed more than 97 % (293/300) identity with a sequence of a Borrelia sp. detected in blood collected from a bat from Macaregua Cave, Colombia, and more than 97 % (292/300) detected in lungs from vampire bats from northeastern Brazil. The deduced amino acid sequences were identical to each other. Phylogenetic analysis indicated that these sequences formed a group of Borrelia species (putatively associated with bats) that is closely related to sequences of Borrelia species of the Lyme borreliosis group. Further investigations should be carried out in order to determine whether the sequence of the Borrelia sp. we found belongs to a new taxon. It will also be of great importance to determine which vertebrate hosts, besides bats, O. cavernicolous ticks can parasitize in order to investigate whether the Borrelia sp. we found may be transmitted and cause disease to the other vertebrate hosts.

Evaluation of a mimotope of the Rickettsia outer membrane protein A (OmpA) as an antigen in enzyme-linked immunosorbent assay to detect rickettsiosis in capybaras (Hydrochoerus hydrochaeris), horses (Equus caballus), and opossums (Didelphis sp.).

Rickettsia rickettsii is the etiological agent of Rocky Mountain spotted fever, which is an important tick-borne zoonosis and, in Brazil, it causes Brazilian spotted fever, which has high lethality rate. This study aimed to evaluate a synthetic peptide corresponding to a segment of the outer membrane protein A (OmpA) as an antigen in a serological test for the diagnosis of rickettsial infections. The amino acid sequence of the peptide was selected by predicting B cell epitopes using B Cell Epitope Prediction (Immune Epitope Database and Analysis Resource) and Epitopia and OmpA sequences of Rickettsia rickettsii strain 'Brazil' and Rickettsia parkeri strains 'Maculatum 20' and 'Portsmouth'. A peptide with amino acid sequence common to both Rickettsia species was synthesized and arbitrarily named OmpA-pLMC. To evaluate this peptide in enzyme-linked immunosorbent assay (ELISA), serum samples of capybara (Hydrochoerus hydrochaeris), horse (Equus caballus), and opossum (Didelphis albiventris) that had been previously tested by indirect immunofluorescence assay (IFA) for rickettsial infection were separated into IFA-positive and IFA-negative groups and used in the assay. There were no significant differences in ELISA optical density (OD) values between IFA-positive and IFA-negative groups with horse samples. The mean OD values were significantly higher in the IFA-positive capybara serum samples (IFA-pos vs. IFA-neg = 2.389 ± 0.761 vs. 1.760 ± 0.840). However, receiver operating characteristic (ROC) curve analysis did not show significant diagnostic parameters. On the other hand, 12 out of 14 (85.7%) opossum samples of the IFA-positive group showed reactivity in ELISA, and this was significantly higher than of the IFA-negative group (0.7196 ± 0.440 vs. 0.2318 ± 0.098, respectively; 85.7% sensitivity, 100% specificity). Therefore, our results show that OmpA-pLMC has a potential to be used in immunodiagnostic assays to detect spotted fever group rickettsial infections.

Tick fauna in non-anthropogenic areas in Mato Grosso do Sul, Brazil, with the presence of the Rickettsia parkeri strain Atlantic rainforest in Amblyomma ovale.

The aim of this study was to evaluate tick fauna and identify the possible presence of Rickettsia spp. in ticks of the genus Amblyomma from two environmental preservation areas in different regions of Mato Grosso do Sul state, Brazil. CO2 traps, visual observation and cloth dragging were used to capture ticks. Three hundred ticks were submitted to the hemolymph test, and samples that showed organisms morphologically compatible with Rickettsia were used for rickettsial DNA detection by PCR. DNA was extracted using guanidine-phenol isothiocyanate, and the primers CS78 and CS323 were used for PCR, which amplified a 401-base pair fragment of the citrate synthase (gltA) gene. If positive, the DNA sample was tested by primers Rr190.70p and Rr190.602n that produce a 530 bp amplicon of the ompA gene that is present only in rickettsiae of the spotted fever group. A total of 1,745 adult ticks were collected, including 1,673 specimens of Amblyomma sculptum, 63 of Amblyomma coelebs, five of Amblyomma naponense and four of Amblyomma ovale. Thirteen ticks of the species A. ovale, A. coelebs and A. sculptum showed structures compatible with Rickettsia inside the hemocytes; after DNA extraction, the presence of Rickettsia spp. in a sample of A. ovale was confirmed by PCR in both analyzed fragments. In the sequencing analysis, 100% identity for the Rickettsia parkeri strain Atlantic rainforest was obtained according to GenBank. The two environmental preservation areas showed A. sculptum as the predominant species, as well as the presence of marked seasonality for this species. This paper is the first report of the R. parkeri strain Atlantic rainforest in A. ovale ticks in the state of Mato Grosso do Sul, Brazil.

Ticks (Acari: Ixodidae) on marsh deer (Blastocerus dichotomus) at a conservation center: infestation and Rickettsia parkeri infection dynamics along nine years.

The objective of this work was to evaluate the relationship between the populations of the ticks Amblyomma triste Koch, 1844, Rhipicephalus microplus (Canestrini, 1888), Amblyomma sculptum Berlese, 1888, the pathogenic bacteria Rickettsia parkeri and a marsh deer (Blastocerus dichotomus) population after its removal from a pristine environment. For this purpose, ticks were collected from the cervical region of deer at the Marsh Deer Conservation Center in Promissão, São Paulo State, Brazil for nine consecutive years (2000 - 2008). Deer in captivity at the Center were kept in 2,000 m² paddocks surrounded by two-meter-high fences in the Tiete-river marsh. In total, 1,012 ticks of 26 deer were collected. Prevalence of the species A. triste among tick-infested hosts was the highest in the first triennium but decreased to the second and further to the third triennium. In contrast, the R. microplus prevalence amidst infested host population, increased from the first to the third triennium and was the species that attained the highest infestation intensity. Amblyomma sculptum was the tick with the lowest infestation prevalence and intensity throughout the period. The change in the proportion between the two most prevalent species was attributed to the new environment, specifically its restricted size and within it a dry area more suitable for R. microplus. DNA of 424 ticks processed in 276 pools was tested for Rickettsia genetic material by polymerase chain reactions (PCR). Twenty samples of the study were positive for the rickettsial gltA gene. Of these, 18 were from A. triste ticks and revealed the presence of the ompA spotted fever group gene as well. Eleven samples were sequenced and showed 100% identity with R. parkeri sensu stricto. Two samples from R. microplus did not amplify ompA gene neither yielded product in a PCR specific for Rickettsia bellii. Sequencing of the gltA gene in the DNA of these two ticks was also 100% identical with R. parkeri s.s. In conclusion, the changes in the deer environment modified the tick populations but maintained, at least temporary, R. parkeri bacteria in A. triste ticks. Rhipicephalus microplus was refractory to the R. parkeri infection and bacterial DNA in this tick species indicated DNA spill over from other tick species. It was demonstrated that captive marsh deer may sustain cattle tick populations on its own. This would hardly occur under pristine conditions because of the inadequacy the marsh deer´s naturally humid habitat for the cattle tick. However, deer transportations of R. microplus ticks from one farm to another may occur whenever habitat loss pushes this wild animal towards farms.

Evidence of acaricide resistance in different life stages of Amblyomma mixtum and Rhipicephalus microplus (Acari: Ixodidae) collected from the same farm in the state of Veracruz, Mexico.

The objectives of this study were to evaluate the resistance of Amblyomma mixtum and Rhipicephalus microplus ticks from co-infested bovines from the Veracruz region in Mexico to different acaricide families and to demonstrate the viability of the packet test on different A. mixtum instars. The following acaricide families were used: a combination (cypermethrin 15 g + chlorpyrifos 25 g + citronella 1 g + butoxide piperonyl 15 g), amidine (formamidine 12.5 g), pyrethroid (cypermethrin 15 g), and organophosphate (dichlorvos 60 g + chlorpyrifos 20 g). Regarding the packet test in both species, resistance was found for the pyrethroid and amidine families in A. mixtum and R. microplus, as efficacy did not surpass 40 %, including in immature instars; regarding the adult immersion test in R. microplus, the efficacy was 93.3 % for the amidine family and 26.2 % for the pyrethroid family. The proposed methodology is an alternative technique to optimize resistance detection in immature ticks with a heteroxenous life cycle.

Amblyomma scalpturatum Neumann, 1906 (Acari: Ixodidae): confirmation in Acre State, Brazil, and description of parasitism in a human.

Amblyomma scalpturatum is a tick species that is unique to South America. It is commonly associated with the Amazon biome and has been reported in some Brazilian states. This tick species exhibits host specificity: it parasitizes tapirs and suidae. Its role in transmitting pathogens to humans is still unknown. Amblyomma scalpturatum is known to be a human-biting tick; however, there is only one report showing that humans make suitable hosts for this species. The knowledge of tick fauna is lacking in the Acre State. This study collected free-living ticks with the aim of finding new records in Acre State. Collections were carried out in Amazon forest fragments in Rio Branco municipality. An A. scalpturatum specimen was identified and submitted sequencing of the ITS-2 gene. This study presents the first molecular confirmation of A. scalpturatum collected in situ in Acre State, North Region, Brazil. This study also presents the first record of a successfully completed feeding by an A. scalpturatum nymph on a human host in the North region of Brazil. Further investigation is needed to ascertain the complete life cycle of this tick species, its seasonality in the environment, and its relationship to pathogens and competence to transmit them.

Economic performance evaluation of Brangus and Nellore cattle breed naturally infested with Rhipicephalus microplus in an extensive production system in Central-West Brazil.

The objective of the present study was to evaluate the performance of Brangus and Nellore cattle in an extensive production system. Sixty growing bulls, 30 of the Brangus and 30 of the Nellore breeds that were naturally infested with Rhipicephalus microplus were subdivided into four groups: control Nellore (15 animals), treated Nellore (15), control Brangus (15), and treated Brangus (15). The animals in the treated groups underwent acaricidal treatments for 1 year. Tick counts, acaricidal treatments and animal weighing were performed every 18 days, and the costs of acaricidal, anti-myiasis, and preventive treatments for tick fever were recorded for cost evaluation. The treated Brangus and Nellore groups did not show a significant difference in weight gain, whereas Nellore weight gain was superior in the control groups. The cost of acaricidal treatment throughout the experimental period was $494 US. The costs of the preventive treatment for tick fever and myiasis were $98 US and $15 US, respectively. The highest rates of tick infestation were found in the control group of the Brangus animals, which served as the basis for the suggested implementation of a strategic control program for animals in the growth phase. Nellore animals showed low rates of infestation. Under the conditions of this study, the Nellore animals were more efficient than the Brangus animals because they achieved satisfactory weight gain, similar to the Brangus, and a low tick count even in the control group. This finding demonstrates that expenses related to the acaricidal, anti-myiasis and tick fever treatments are unnecessary in Nellore cattle, making these animals more profitable.

Amblyomma scalpturatum Neumann, 1906 (Acari: Ixodidae): confirmation in Acre State, Brazil, and description of parasitism in a human / Amblyomma scalpturatum Neumann, 1906 (Acari: Ixodidae): confirmação no Estado do Acre, Brasil, e descrição de parasitismo em um humano

Abstract Amblyomma scalpturatum is a tick species that is unique to South America. It is commonly associated with the Amazon biome and has been reported in some Brazilian states. This tick species exhibits host specificity: it parasitizes tapirs and suidae. Its role in transmitting pathogens to humans is still unknown. Amblyomma scalpturatum is known to be a human-biting tick; however, there is only one report showing that humans make suitable hosts for this species. The knowledge of tick fauna is lacking in the Acre State. This study collected free-living ticks with the aim of finding new records in Acre State. Collections were carried out in Amazon forest fragments in Rio Branco municipality. An A. scalpturatum specimen was identified and submitted sequencing of the ITS-2 gene. This study presents the first molecular confirmation of A. scalpturatum collected in situ in Acre State, North Region, Brazil. This study also presents the first record of a successfully completed feeding by an A. scalpturatum nymph on a human host in the North region of Brazil. Further investigation is needed to ascertain the complete life cycle of this tick species, its seasonality in the environment, and its relationship to pathogens and competence to transmit them.

Resumo Amblyomma scalpturatum é uma espécie de carrapato que ocorre apenas na América do Sul. Está comumente associada ao bioma da Amazônia e tem sido relatada em alguns estados brasileiros. Esta espécie de carrapato apresenta especificidade a hospedeiros: parasita antas e suídeos. Sua competência em transmitir agentes patogênicos a seres humanos é ainda desconhecida. Amblyomma scalpturatum é também conhecido por picar seres humanos; entretanto, há apenas um relato que evidencie que seres humanos sejam capazes de serem hospedeiros adequados. Ainda existem lacunas no conhecimento sobre a ixodofauna no estado do Acre. Neste estudo foram coletados carrapatos de vida livre com o objetivo de encontrar novos registros para o estado do Acre. Coletas de carrapatos foram realizadas em fragmentos de floresta Amazônica no município de Rio Branco. Um exemplar de A. scalpturatum foi identificado e submetido a sequenciamento do gene ITS-2. Este estudo apresenta a primeira confirmação molecular de A. scalpturatum coletado in situ no estado do Acre, região Norte, Brasil. Este estudo também apresenta o primeiro relato de parasitismo completo de uma ninfa de A. scalpturatum em um hospedeiro humano na região Norte do Brasil. Mais investigações são necessárias para elucidar o ciclo de vida completo dessa espécie de carrapato, a sazonalidade de seus estádios no meio ambiente, sua relação a agentes patogênicos e competência em transmiti-los.

Wildlife species, Ixodid fauna and new host records for ticks in an Amazon forest area, Rondônia, Brazil / Espécies de vida selvagem, fauna ixodídica e novos registros de hospedeiros de carrapatos em uma área de Floresta Amazônica, Rondônia, Brasil

Abstract The objective of this work was to evaluate the diversity of ticks associated with free-living animals and to investigate new host records for ticks. Ticks were collected from animals rescued during the flood of the Jamari River in the municipality of Ariquemes, state of Rondônia, North Region of Brazil. A total of 39 animals were captured, out of which 10 were amphibians, 19 were reptiles and 10 were mammals. A total of 127 ticks of the Amblyomma genus were collected from these animals, distributed among seven species: Amblyomma dissimile, Amblyomma geayi, Amblyomma humerale , Amblyomma longirostre, Amblyomma nodosum , Amblyomma rotundatum and Amblyomma varium. In addition, one specimen of Rhipicephalus (Boophilus) microplus was collected. Among these specimens, 85 were adults and 42 were nymphs, with A. rotundatum being the most prevalent species. An Amblyomma spp. larvae was also collected from a lizard (Uranoscodon superciliosus), and one Amblyomma calcaratum and one Amblyomma dubitatum were recovered from the environment, thus totaling 130 ticks. Among the Ixodidae collected from different hosts, we provide the first report for the species A. rotundatum parasitizing Rhinella major, U. superciliosus, Leptophis ahaetulla, Chironius multiventris, and Mastigodryas boddaerti, as well as of A. humerale parasitizing U. superciliosus, A. geayi parasitizing Choloepus didactylus, and Rhipicephalus (B.) microplus parasitizing Alouatta puruensis.

Resumo O objetivo deste trabalho foi avaliar a diversidade de carrapatos associados à animais de vida livre e investigar novos registros de hospedeiros. Coletas foram feitas em animais resgatados durante a cheia do Rio Jamari, localizado no município de Ariquemes, estado de Rondônia, Região Norte do Brasil. Um total de 39 animais foi capturado, dos quais dez eram anfíbios, 19 eram répteis e dez eram mamíferos. 127 carrapatos do gênero Amblyomma foram coletados destes animais, distribuídos em sete espécies: Amblyomma dissimile , Amblyomma geayi, Amblyomma humerale, Amblyomma longirostre, Amblyomma nodosum, Amblyomma rotundatum e Amblyomma varium. Adicionalmente, um exemplar de Rhipicephalus (Boophilus) microplus foi coletado. Dentre estes espécimes, 85 eram adultos e 42 eram ninfas, com A. rotundatum sendo a espécie mais prevalente. Uma larva de Amblyomma spp. também foi coletada de um lagarto (Uranoscodon superciliosus), um Amblyomma calcaratum e um Amblyomma dubitatum foram recuperados do ambiente, assim totalizando 130 carrapatos. Dentre os ixodídeos coletados de diferentes hospedeiros, este trabalho fornece o primeiro registro da espécie A. rotundatum parasitando Rhinella major, U. superciliosus, Leptophis ahaetulla, Chironius multiventris e Mastigodryas boddaerti, assim como da espécie A. humerale parasitando U. superciliosus , a espécie A. geayi parasitando Choloepus didactylus e R. microplus parasitando Alouatta puruensis .

Wildlife species, Ixodid fauna and new host records for ticks in an Amazon forest area, Rondônia, Brazil.

The objective of this work was to evaluate the diversity of ticks associated with free-living animals and to investigate new host records for ticks. Ticks were collected from animals rescued during the flood of the Jamari River in the municipality of Ariquemes, state of Rondônia, North Region of Brazil. A total of 39 animals were captured, out of which 10 were amphibians, 19 were reptiles and 10 were mammals. A total of 127 ticks of the Amblyomma genus were collected from these animals, distributed among seven species: Amblyomma dissimile, Amblyomma geayi, Amblyomma humerale , Amblyomma longirostre, Amblyomma nodosum , Amblyomma rotundatum and Amblyomma varium. In addition, one specimen of Rhipicephalus (Boophilus) microplus was collected. Among these specimens, 85 were adults and 42 were nymphs, with A. rotundatum being the most prevalent species. An Amblyomma spp. larvae was also collected from a lizard (Uranoscodon superciliosus), and one Amblyomma calcaratum and one Amblyomma dubitatum were recovered from the environment, thus totaling 130 ticks. Among the Ixodidae collected from different hosts, we provide the first report for the species A. rotundatum parasitizing Rhinella major, U. superciliosus, Leptophis ahaetulla, Chironius multiventris, and Mastigodryas boddaerti, as well as of A. humerale parasitizing U. superciliosus, A. geayi parasitizing Choloepus didactylus, and Rhipicephalus (B.) microplus parasitizing Alouatta puruensis.

Biological parameters of Amblyomma coelebs Neumann, 1906 (Acari: Ixodidae) under experimental conditions.

One generation of Amblyomma coelebs life cycle under experimental conditions was evaluated. Ten tick pairs were allowed to feed on rabbits under laboratory conditions (LC), resulting six engorged females with a mean weight of 1,403.9 mg. Two females were maintained in a forest reserve under natural conditions (NC), and four were maintained in incubators (LC). The engorgement period lasted 10.33 days. Pre-oviposition periods were 10.75 (NC) and 22 days (LC). The mean egg-mass weight was 514.76 mg, and the blood meal conversion index was 36.67% (LC). Incubation period under NC and LC were 91 and 56.33 days and hatching rates were 50% and 28.33%, respectively. Larval engorgement period ranged from 4 to 10 days, with average weight of 1.1 mg. Engorged larvae were incubated under NC and LC, with a premolt period of 27 to 36 days and molting rate of 7.1% and 28.7%, respectively. Nymphal engorgement period ranged from 5 to 7 days, with a mean weight of 18.8 mg and a recovery rate of 54.54%. In LC, the ecdysis mean period was 24.5 days, and molting rate was 44.44%, resulting in 24 adult A. coelebs. Our results show a life cycle of 187.45 (NC) and 149 (LC) days.

New records of tick-associated spotted fever group Rickettsia in an Amazon-Savannah ecotone, Brazil.

Human rickettsiosis has been recorded in the Amazon Biome. However, the epidemiological cycle of causative rickettsiae has not been fully accounted for in the Amazon region. This study investigates the presence of spotted fever group (SFG) Rickettsia spp. in free-living unfed ticks of the Amblyomma genus. The study was conducted in seven municipalities in Rondonia State, Brazil, where the main biomes are Amazon forest, Brazilian Savannah and their ecotones (areas of ecological tension between open ombrophilous forest and savannah). The following tick species were collected: Amblyomma cajennense (sensu lato) s.l., A. cajennense (sensu stricto) s.s., A. coelebs, A. naponense, A. oblongoguttatum, A. romitii, A. scalpturatum and A. sculptum. A total of 167 adults, 248 nymphs and 1004 larvae were subjected to DNA extraction and polymerase chain reaction (PCR) to determine the presence of SFG Rickettsia spp. PCR-positive samples included: one A. cajennense s.s. female and one A. cajennense s.l. male from a rural area in Vilhena Municipality; 10 nymphs and a sample of larvae of A. cajennense s.l. from a peri-urban area in Cacoal Municipality; and an A. oblongoguttatum adult male from a rural area of Pimenta Bueno Municipality. All sequences obtained exhibited 100% identity with Rickettsia amblyommatis sequences. This is the first confirmation of SFG Rickettsia in an A. oblongoguttatum tick. Furthermore, this is the first record of SFG Rickettsia in the municipalities targeted by this study. These results warn that SFG Rickettsia circulation poses a threat in Rondonia State (among Amazon-Savannah ecotones), and that this threat is increased by the fact that SFG Rickettsia infect a human-biting tick species hitherto unconfirmed as a vector.

Biological parameters of Amblyomma coelebs Neumann, 1906 (Acari: Ixodidae) under experimental conditions / Parâmetros biológicos de Amblyomma coelebs Neumann, 1906 (Acari: Ixodidae) em condições experimentais

Abstract One generation of Amblyomma coelebs life cycle under experimental conditions was evaluated. Ten tick pairs were allowed to feed on rabbits under laboratory conditions (LC), resulting six engorged females with a mean weight of 1,403.9 mg. Two females were maintained in a forest reserve under natural conditions (NC), and four were maintained in incubators (LC). The engorgement period lasted 10.33 days. Pre-oviposition periods were 10.75 (NC) and 22 days (LC). The mean egg-mass weight was 514.76 mg, and the blood meal conversion index was 36.67% (LC). Incubation period under NC and LC were 91 and 56.33 days and hatching rates were 50% and 28.33%, respectively. Larval engorgement period ranged from 4 to 10 days, with average weight of 1.1 mg. Engorged larvae were incubated under NC and LC, with a premolt period of 27 to 36 days and molting rate of 7.1% and 28.7%, respectively. Nymphal engorgement period ranged from 5 to 7 days, with a mean weight of 18.8 mg and a recovery rate of 54.54%. In LC, the ecdysis mean period was 24.5 days, and molting rate was 44.44%, resulting in 24 adult A. coelebs. Our results show a life cycle of 187.45 (NC) and 149 (LC) days.

Resumo Uma geração do ciclo de vida de Amblyomma coelebs em condições laboratoriais foi avaliada. Dez casais de carrapatos foram alimentados em coelhos sob condições laboratoriais (CL), resultando em seis fêmeas ingurgitadas, com um peso médio de 1.403,9 miligramas (mg). Duas fêmeas foram mantidas em uma reserva florestal sob condições naturais (CN), e quatro foram mantidas em incubadoras (CL). O período de ingurgitamento durou 10,33 dias. Períodos de pré-postura foram de 10,75 (CN) e 22 dias (CL). O peso médio das massas de ovos foi de 514,76 mg e o índice de conversão alimentar foi de 36,67% (CL). O período de incubação em CN e CL foi de 91 e 56,33 dias e os percentuais de eclosão foram de 50% e 28,33%, respectivamente. O período de ingurgitamento larval variou de quatro a 10 dias, com peso médio de 1,1 mg. Larvas ingurgitadas foram incubadas em CN e CL, com período de pré-muda de 27 a 36 dias e percentual de ecdise de 7,1% e 28,7%, respectivamente. O período de ingurgitamento das ninfas oscilou de cinco a sete dias, com peso médio de 18,8 mg e uma taxa de recuperação de 54,54%. Em CL, o período médio de ecdise foi de 24,5 dias, e o percentual de muda foi 44,44%, resultando em 24 adultos de A. coelebs. Estes resultados demonstram um ciclo de vida de 187,45 (CN) e 149 (CL) dias.

Efficacy profile of Cypermethrin and Chlorpyrifos based acaricides on Rhipicephalus microplus control on cattle in the rearing phase, naturally infested and exposed to tick fever agents in central Brazil.

The objective of this work was to evaluate the efficacy of two cypermethrin- and chlorpyrifos-based acaricides in controlling Rhipicephalus microplus in a naturally infested bovine herd and in in vitro tests, as well as to monitor the animals for tick fever. Male bovines in the rearing phase were used, with 30 Brangus and 30 Nellore animals naturally infested. The groups were composed as follows: 15 Nellore treated, 15 Nellore control, 15 Brangus treated and 15 Brangus control. Every 18 days, the animals were monitored for tick count, acaricide treatment, weight, blood pack cell volume, and clinical signs. For in vitro tests, the larval packet test, adult immersion test and DNA amplification for tick fever diagnosis were performed. In the first animal treatment period, product 1 (cypermethrin, 15 g + chlorpyrifos, 25 g + citronellal, 1 g) was used; in the second period, product 2 (cypermethrin, 15 g + chlorpyrifos, 30 g + fenthion, 15 g) was used. In Brangus animals, the mean efficacy was 35.1% and 95.8% in the first and second periods, respectively, for the same animals. For Nellore animals, the efficacy in periods one and two was 51% and 97.1%, respectively. The in vitro results showed efficacy above 95% for the two challenged acaricides. The Brangus animals showed a high production of ticks associated with the presence of tick fever agents, which could generate risks for the disease's enzootic stability.

Ixodidae fauna of domestic dogs in Parana, southern Brazil / Fauna ixodídica em cães domésticos no Paraná, Sul do Brasil

Abstract The present study aimed to contribute towards identification and registration of tick species that parasitize dogs in rural and urban areas of three mesoregions of Paraná, southern Brazil, and to estimate the rate of occurrence of each species. Fifty-six dogs with ticks living in three mesoregions: Metropolitana de Curitiba (MC), Centro Oriental (COP) and Centro Sul Paranaense (CSP), were used in the study. From these 56 dogs, 253 ticks were collected and were identified and morphologically characterized according to the species. Among all the ticks, 69.6% were identified as belonging to the species Rhipicephalus sanguineus sensu lato (s. l.); 28.1% as Amblyomma aureolatum and 2.4% as Amblyomma ovale. Among the dogs in MC that were evaluated, 57.7% were parasitized by R. sanguineus s. l., 38.5% by A. aureolatum and 3.8% by A. ovale; while in COP, 72.4% of the dogs were parasitized by A. aureolatum and 27.6% by R. sanguineus s. l.. In CSP, one tick was obtained, which was identified as A. aureolatum.

Resumo O presente estudo objetivou contribuir com a identificação e o registro das espécies de carrapatos que parasitam cães de áreas rurais e urbanas de três mesorregiões do Paraná, Sul do Brasil, e estimar a taxa de ocorrência de cada espécie. Cinquenta e seis cães com carrapatos, provenientes das mesorregiões: Metropolitana de Curitiba (MC), Centro Oriental (COP) e Centro Sul Paranaense (CSP) foram utilizados no estudo. Dos 56 cães, foram coletados 253 carrapatos que foram identificados e caracterizados morfologicamente de acordo com a espécie. Do total de carrapatos, 69,6% foram identificadas como pertencentes à espécie Rhipicephalus sanguineus s. l.; 28,1% como Amblyomma aureolatum e 2,4% como Amblyomma ovale. Dentre os animais avaliados, provenientes da MC, 57,7% estavam parasitados por R. sanguineus s. l., 38,5% por A. aureolatum e 3,8% por A. ovale; enquanto na COP 72,4% dos cães foram parasitados por A. aureolatum e 27,6% por R. sanguineus s. l.. Na CSP foi obtido um carrapato, identificado como A. aureolatum.

Ixodidae fauna of domestic dogs in Parana, southern Brazil.

The present study aimed to contribute towards identification and registration of tick species that parasitize dogs in rural and urban areas of three mesoregions of Paraná, southern Brazil, and to estimate the rate of occurrence of each species. Fifty-six dogs with ticks living in three mesoregions: Metropolitana de Curitiba (MC), Centro Oriental (COP) and Centro Sul Paranaense (CSP), were used in the study. From these 56 dogs, 253 ticks were collected and were identified and morphologically characterized according to the species. Among all the ticks, 69.6% were identified as belonging to the species Rhipicephalus sanguineus sensu lato (s. l.); 28.1% as Amblyomma aureolatum and 2.4% as Amblyomma ovale. Among the dogs in MC that were evaluated, 57.7% were parasitized by R. sanguineus s. l., 38.5% by A. aureolatum and 3.8% by A. ovale; while in COP, 72.4% of the dogs were parasitized by A. aureolatum and 27.6% by R. sanguineus s. l.. In CSP, one tick was obtained, which was identified as A. aureolatum.

Life cycle and parasitic competence of Dermacentor nitens Neumann, 1897 (Acari: Ixodidae) on different animal species.

The objective of this study was to evaluate the life cycle and parasitic competence of Dermacentor nitens (Neumann, 1897) on different animal species. Experimental infestations were induced in five specimens each of seven species of possible hosts: rabbits, horses, sheep, cows, guinea pigs, birds and dogs. Rabbits were infested in the ear using artificial feeding chambers, and the horses, sheep, cows and dogs were infested in the ear without feeding chambers. For the infestation of guinea pigs, artificial feeding chambers were fixed on the back. Birds were infested by placing larvae on the back and under the wings without the use of chambers. All animals were inspected daily until the end of the parasitic phase (when the engorged females detached). The average period of engorgement was 25.1days on a horse, with larvae requiring 8days and nymphs 9days to reach engorgement; the average weight of engorged females was 271.4mg; the average weight of egg batches produced was 159.3mg, and the feed conversion rate was 56.8%. On rabbits, the average engorgement period was 27.6days, larvae and nymphs reached engorgement after 7.4 and 11days, respectively, the average weight of an engorged female was 108.4mg and the egg mass was 30.6mg. The feed conversion rate on rabbits was 30%. Cows, sheep, guinea pigs, dogs and birds were not competent hosts, since no engorged females were recovered. Rabbits, when artificially infested, can be used as an alternative host for the maintenance of these ticks in the laboratory. The parasitic specificity of D. nitens for horses was demonstrated in this study.

Efficacy of Tagetes minuta (Asteraceae) essential oil against Rhipicephalus sanguineus (Acari: Ixodidae) on infested dogs and in vitro.

Ticks from Rhipicephalus sanguineus complex are widely distributed in the world and one species from this complex is the most common tick on dogs in Brazil, notably in urban areas. This tick is a vector of several diseases. Among others it transmits the agent of canine Ehrlichiosis, a major dog infectious disease and the agent of Rocky Mountain spotted fever. This tick can spread rapidly and develop intolerable infestations within no time. Currently tick control is done with acaricides and demand for such drugs has grown fast. However, R. sanguineus has already developed resistance to the main active compounds and the development of new acaricides is necessary. Many essential oils of plants have acaricidal effect and may be an important source of molecules for the synthesis of new acaricide products. In this study, we evaluated the effectiveness of a new herbal phytotherapic, consisting of the essential oil of Tagetes minuta L., against R. sanguineus in vitro and on dogs undergoing experimental infestations. The product displayed 100% efficacy against larvae, nymphs and adults of the tick on all tested conditions.