Crude saliva of Amblyomma cajennense sensu stricto (Acari: Ixodidae) reduces locomotor activity and increases the hemocyte number in the females of Aedes aegypti (Diptera: Culicidae).

Aedes aegypti are vector insects of arboviruses such as dengue, Zika, and chikungunya. All available vector control methods have limited efficacy, highlighting the urgent need to find alternative ones. Evidence shows that arachnids like ticks are sources of biologically active compounds. Moreover, chemical modulation of the locomotor and immune systems of vector insects can be used to control arbovirus transmission. The present study evaluated the effectiveness of crude saliva of female Amblyomma cajennense sensu stricto (s.s.) ticks in reducing locomotor activity and inducing an immune response in Ae. aegypti females. Additionally, the study evaluated the protein constitution of tick saliva. For this purpose, the crude saliva obtained from several semi-engorged A. cajennense females was used. A volume of 0.2 nL of crude tick saliva was administered to mosquitoes by direct intrathoracic microinjection. The effect of the tick's saliva on the locomotor activity of the mosquito was observed using Flybox, a video-automated monitoring system, and the hemolymph hemocyte levels were quantified by reading slides under a light microscope. The protein concentration of the crude tick saliva was 1.27 µg/µL, and its electrophoretic profile indicates the presence of proteins with a molecular weight ranging between ∼17 and 95 kDa. Microplusins, ixodegrins, cystatin, actins, beta-actin, calponin, albumin, alpha-globulins, and hemoglobin were the main proteins identified by proteomics in the saliva of A. cajennense. The microinjected saliva had low toxicity for Ae. aegypti females and significantly reduced their locomotor activity, especially in the transition between the light and dark phases. The crude tick saliva did not change the period and rhythmicity of the circadian cycle. The tick saliva significantly increased the number of hemocytes two days after injection and reduced it after five days. These results suggest that further evaluation of the biological properties of tick saliva proteins against Ae. aegypti would be of interest.

Inaccurate recording of Mansonella perstans in free-ranging primates outside its endemic area in Brazil?

In the study undertaken by Souza et al. [Primates 64(1):153-159, 2022; https://doi.org/10.1007/s10329-022-01038-5 ], published in the most recent volume of this journal, the blood samples of two Alouatta guariba clamitans (Primates, Atelidae) from two municipalities in the state of Rio Grande do Sul, southern Brazil were reported to be positive for Mansonella perstans. This is the first reported finding of M. perstans in A. guariba clamitans, as well as the first time that M. perstans has been recorded in Brazil outside the Amazon region. We would like to express our concern about this finding, specifically with respect to the geographical distribution of M. perstans in Brazil, as, up until this study, this filaria had only been found in the upper Rio Negro region in São Gabriel da Cachoeira, Amazonas, Brazil. Moreover, species identification was performed using partial sequences of three gene fragments, namely internal transcribed spacer 2, 12S, and 18S, yet neither the phylogenetic trees nor the BLAST alignments of these sequences provided supporting evidence that they belong to M. perstans.

Parasitism by Amblyomma rotundatum on Teiidae lizards in the eastern part of the state of Acre, Brazil.

The aim of the present study was to report on the occurrence of parasitism by Amblyomma rotundatum ticks on two species of Teiidae lizards and test the presence of rickettsiae in the collected ticks, in the western Brazilian Amazon region. Ticks were collected in July 2019, from a fragment of terra firme forest in the municipality of Senador Guiomard, Acre, Brazil. Two lizards that were infested by immature stages of ticks were caught using mist net and Tomahawk traps. Ectoparasites were collected manually, and the lizard specimens were identified and released at the same location where they had been caught. Three nymphs and 49 larvae were collected from Ameiva ameiva, while 25 nymphs and nine larvae were collected from Tupinambis cuzcoensis, which are both in the family Teiidae. The ticks were identified morphologically as belonging to the genus Amblyomma. Nymphs were identified at species level through molecular analysis, resulting in the tick species Amblyomma rotundatum. This is the first record of parasitism by the tick A. rotundatum on T. cuzcoensis lizard, and the first report of an association between A. rotundatum and the lizard species A. ameiva and T. cuzcoensis in Acre, in the western part of the Amazon region.

Rickettsia parkeri strain Atlantic rainforest infecting Amblyomma ovale (Acari: Ixodidae) in the Amazon Biome (Acre state, Brazil).

There is a lack of studies regarding tick-associated Rickettsia in the Amazon biome. Aiming to contribute to this knowledge, our research group collected ticks in the Western Amazon to better understand the tick fauna and their associated Rickettsia. In this study, we detected Rickettsia parkeri strain Atlantic rainforest DNA in the tick Amblyomma ovale Koch, 1844 in Rio Branco municipality, Acre state, northern Brazil. This is the first time that the R. parkeri strain Atlantic rainforest has been reported in the Amazon biome and is the first evidence of the circulation of a pathogenic spotted fever group (SFG) Rickettsia in this biome. This finding provides substantial information to help public health authorities understand which species of Rickettsia may be related to Amazon spotted fever cases.

Amblyomma ticks in animal carcasses hunted in Mapinguari National Park, Western Amazon, Brazil: New records on species and host-parasite relationships.

Ticks are obligatory parasites and transmit several pathogens to animals and humans. This study aimed to report the parasitism of ticks on carcasses of animals hunted by hunters from communities near Mapinguari National Park, at the shared border of Amazonas and Rondonia states, northern Brazil. The ticks were collected from heads of carcasses of the following animals: South American tapir (Tapirus terrestris), collared peccary (Pecari tajacu) and long-nosed armadillo (Dasypus beniensis). Six Amblyomma tick species were identified: Amblyomma coelebs, Amblyomma naponense, Amblyomma latepunctatum, Amblyomma oblongoguttatum, Amblyomma scalpturatum, Amblyomma triste and Amblyomma spp. The most abundant tick species were A. oblongoguttatum and A. scalpturatum. DNA extraction and polymerase chain reaction (PCR) were performed on all ticks to test for the presence of rickettsial gltA gene fragments, but no amplification was observed. This study reports, for the first time, the parasitism of A. coelebs in the armadillo D. beniensis and the presence of A. triste in the states of Amazonas and Rondonia, updating the tick fauna to 24 and 39 species for these states, respectively.

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.

First report of Amblyomma latepunctatum and the second record of Ixodes luciae in the state of Acre, Brazil.

The state of Acre is in the western part of the Brazilian Amazon region and few studies involving ticks are available. The aim of the present study was to provide the first report of occurrence of Amblyomma latepunctatum and the second record of Ixodes luciae in Acre. Ticks were collected in October 2020 inside an open forested area in the municipality of Rio Branco, the state capital of Acre. Ixodid ticks were identified according to their external morphological characteristics. Three specimens were found on the vegetation by means of a visual search and were identified as Amblyomma scalpturatum (one male and one female) and Amblyomma latepunctatum (one male). Another specimen was found parasitizing a Didelphis marsupialis female that was caught using a Tomahawk trap; this was identified as Ixodes luciae (one male). This first report of A. latepunctatum in the state of Acre increases the number of species recorded here to 22. In addition, presence of I. luciae is confirmed in this state (second record), in the western Brazilian Amazon region.

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.

Analysis of Bm86 conserved epitopes: is a global vaccine against Cattle Tick Rhipicephalus microplus possible?

The cattle tick Rhipicephalus microplus causes significant economic losses in agribusiness. Control of this tick is achieved mainly through the application of chemical acaricides, often resulting in contamination of animal food products and of the environment. Another major concern associated with acaricide use is the increasing reports of resistance of this tick vector against the active ingredients of many commercial products. An alternative control method is vaccination. However, the commercially available vaccine based on a protein homologous to Bm86 exhibits variations in efficacy relative to the different geographical locations. This study aimed to identify antigenic determinants of the sequences of proteins homologous to Bm86. Phylogenetic analyses were performed to determine the extent of divergence between different populations of R. microplus to identify the sequence that could be used as a universal vaccine against the multiple geographically distinct populations of R. microplus and related tick species. Considering the extensive sequence and functional polymorphism observed among strains of R. microplus from different geographical regions, we can conclude that it may be possible to achieve effective vaccination against these cattle ticks using a single universal Bm86-based antigen.

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.

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.

Design of the ATAQ peptide and its evaluation as an immunogen to develop a Rhipicephalus vaccine.

Tick infestation may cause several problems including affecting domestic animal health and reducing the production of meat and milk, among others. Resistance to several classes of acaricides have been reported, forcing researchers to search for alternative measures, such as vaccines against ticks, to ensure tick control while having no or at least low negative impacts on the environment and public health. However, the current commercially available vaccines in different strains of Rhipicephalus microplus are reported to be of low efficacy. Fortunately, reverse vaccinology approaches have shown positive results in the new generation of vaccines. On this basis, a synthetic peptide from the ATAQ protein, which is present in the gut and Malpighi tubes of R. microplus, was synthesized. The ATAQ proteins were isolated, characterized and sequenced from several species of the genus Rhipicephalus. The alignment showed 93.3% identity among DNA sequences of ATAQs from these species. Because of this, immunization trials with this peptide were conducted on mice, rabbits and cattle to evaluate the humoral immune response and the efficacy against Rhipicephalus sanguineus in addition to R. microplus. Based on recent results, we conclude that reverse vaccinology is a promising approach because it is more accurate and faster than conventional methods in the detection of potential antigens to use in anti-tick vaccines. It is not only applicable against R. microplus but also against tick species that play important roles in spreading other diseases. ATAQ proteins should be considered as the antigen in new trials to develop a multi-antigenic vaccine. Although these peptides behave as hapten and are not able to be recognized by the immune system on its own, using carriers and adjuvants helps its presentation and induces strong immune responses. Furthermore, an efficiency of 35% reduction in overall life cycle parameters was reported for R. microplus (98% for ELISA responder animals) and 47% for R. sanguineus. Although not yet enough to prevent the environment to infestation of ticks, this still constitutes a promising strategy that could be applied to integrated measures on tick control and in new research that develops anti-tick vaccines.

First report of Amblyomma latepunctatum and the second record of Ixodes luciae in the state of Acre, Brazil / Primeiro relato de Amblyomma latepunctatum e o segundo registro de Ixodes luciae no estado do Acre, Brasil

Abstract The state of Acre is in the western part of the Brazilian Amazon region and few studies involving ticks are available. The aim of the present study was to provide the first report of occurrence of Amblyomma latepunctatum and the second record of Ixodes luciae in Acre. Ticks were collected in October 2020 inside an open forested area in the municipality of Rio Branco, the state capital of Acre. Ixodid ticks were identified according to their external morphological characteristics. Three specimens were found on the vegetation by means of a visual search and were identified as Amblyomma scalpturatum (one male and one female) and Amblyomma latepunctatum (one male). Another specimen was found parasitizing a Didelphis marsupialis female that was caught using a Tomahawk trap; this was identified as Ixodes luciae (one male). This first report of A. latepunctatum in the state of Acre increases the number of species recorded here to 22. In addition, presence of I. luciae is confirmed in this state (second record), in the western Brazilian Amazon region.

Resumo O estado do Acre está localizado na Amazônia ocidental brasileira e apresenta poucos estudos envolvendo carrapatos. O presente estudo objetivou relatar, pela primeira vez, a ocorrência da espécie Amblyomma latepunctatum e o segundo registro de Ixodes luciae no estado do Acre, Brasil. A coleta de carrapatos foi realizada em outubro de 2020 no interior de uma floresta aberta no município de Rio Branco, capital do estado do Acre. Carrapatos ixodídeos foram identificados de acordo com suas características morfológicas externas. Três espécimes foram encontrados sobre a vegetação pelo método de inspeção visual e identificados como as espécies Amblyomma scalpturatum (um macho e uma fêmea) e Amblyomma latepunctatum (um macho); e outro foi encontrado parasitando uma fêmea de Didelphis marsupialis que foi capturada por uma armadilha Tomahawk, e identificado como Ixodes luciae (um macho). Este primeiro relato de A. latepunctatum no estado do Acre aumenta o número de espécies registradas aqui para 22. Além disso, a presença de I. luciae é confirmada no estado do Acre (segundo registro), na região da Amazônia ocidental brasileira.

Spotted fever group Rickettsia in Amblyomma dubitatum tick from the urban area of Campo Grande, Mato Grosso do Sul, Brazil.

Rickettsia infection of each tick was evaluated by the hemolymph test and polymerase chain reaction (PCR) targeting gltA and ompA genes. All hemolymph tests were negative and PCR of one A. dubitatum detected both Rickettsia genes. Sequence of ompA exhibited a 99% identity with Rickettsia parkeri and R. africae and a 98% identity with R. sibirica. Rickettsia of the spotted fever group in A. dubitatum is described for the first time in an urban area within the municipality of Campo Grande in the state of Mato Grosso do Sul (MS), Brazil. This finding reinforces the importance of more detailed studies to determine the role of A. dubitatum in the transmission of spotted fever agents.

Formula to evaluate efficacy of vaccines and systemic substances against three-host ticks.

The control of ticks with vaccines is of global interest. Experimental vaccines incorporate new technologies as soon as they are available. Historically, the main vaccine studies have focused on the one-host cattle tick Rhipicephalus microplus, and efficacy evaluations have been standardised for this tick species. On the other hand, evaluations of vaccine candidates for three-host ticks are being done somewhat arbitrarily and thus comparisons within the current literature on the efficacy of vaccines, as well as other methods of control, are difficult. We herein provide a formula for the evaluation of efficacy of a vaccine designed against three-host ticks that incorporates the whole life cycle of the tick.

Contributions of the hair sheep breed Santa Ines as a maintenance host for Rhipicephalus (Boophilus) microplus (Acari: Ixodidae) in Brazil.

BACKGROUND: Hair sheep breeds are a new, cost-effective option for the diversification of livestock in the Midwest region of Brazil. They are grazed extensively with cattle as well as in isolation in small areas. Hair sheep breeds are vulnerable to infestation by parasites such as the cattle tick, Rhipicephalus microplus, which causes various types of damage and can transmit diseases. METHODS: In this study, Santa Inês hair sheep were naturally infested in an area contaminated by infested cattle and then monitored to determine the ability of these animals to maintain the local tick population in the absence of cattle. After engorged tick females of each generation fell off, the animals were placed in another pasture and were returned only after larvae reappeared in the original pasture. RESULTS: Tick counts were performed every ten days for three generations of sheep, and average infestations per animal of 34, 12 and 4 ticks were observed for each successive generation. These numbers suggest the acquisition of resistance; however, additional studies are needed to ensure resistance is achieved. The average length of the parasitic phase for each generation of ticks was 25 days. CONCLUSION: We concluded that this hair sheep breed, even if kept separate from cattle, is able to maintain tick populations for at least three generations, although a gradual decrease in the population levels of R. microplus over three generations was observed. We also detected two positive cases of Anaplasma spp. Therefore, it appears that the Santa Inês hair sheep breed contributes to the circulation of this bacterium among other ruminants.

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.

Calculation of the efficacy of vaccines against tick infestations on cattle.

Cattle ticks are responsible for great economic losses in cattle farming worldwide, and their main control method, chemicals, has been showing problems, whether resulting from the development of resistant strains of ticks or environmental contamination. Research studies directed toward developing vaccines against ticks are emerging. One way to evaluate those vaccines is to calculate the percentage of efficacy. The aim of this study was to analyze scientific publications archived in PubMed that used this method of assessment and discuss the main factors that may affect its calculation. Thus, 25 articles addressing this subject were selected. The percentage of efficacy was usually calculated in one of two ways, with one considering the reduced fertility of eggs and the other not. The latter method may underestimate the vaccine efficacy, and the most complete formula for calculating the efficacy reflects how much the vaccine actually affects the infestation. In our view, the use of the complete formula for calculating the percentage of efficacy is broader and more representative of the vaccine effect on the tick population.

Analysis of Bm86 conserved epitopes: is a global vaccine against Cattle Tick Rhipicephalus microplus possible? / Análise de epítopos conservados da Bm86: é possível uma vacina global contra Carrapato-do-Boi Rhipicephalus microplus?

Abstract The cattle tick Rhipicephalus microplus causes significant economic losses in agribusiness. Control of this tick is achieved mainly through the application of chemical acaricides, often resulting in contamination of animal food products and of the environment. Another major concern associated with acaricide use is the increasing reports of resistance of this tick vector against the active ingredients of many commercial products. An alternative control method is vaccination. However, the commercially available vaccine based on a protein homologous to Bm86 exhibits variations in efficacy relative to the different geographical locations. This study aimed to identify antigenic determinants of the sequences of proteins homologous to Bm86. Phylogenetic analyses were performed to determine the extent of divergence between different populations of R. microplus to identify the sequence that could be used as a universal vaccine against the multiple geographically distinct populations of R. microplus and related tick species. Considering the extensive sequence and functional polymorphism observed among strains of R. microplus from different geographical regions, we can conclude that it may be possible to achieve effective vaccination against these cattle ticks using a single universal Bm86-based antigen.

Resumo O carrapato Rhipicephalus microplus é responsável por perdas significativas no agronegócio. O controle deste carrapato é feito principalmente por meio da aplicação de acaricidas químicos, geralmente resultando na contaminação de produtos de origem animal e do meio ambiente. Outra preocupação importante associada ao uso de acaricidas é o crescente aumento de relatos sobre a resistência deste carrapato a princípios ativos de vários produtos comerciais. Uma alternativa de controle é por meio de vacinação. Porém, a vacina comercializada contendo proteína homóloga à Bm86, apresenta variações de eficácia em relação às diferentes localizações geográficas. Este estudo buscou identificar determinantes antigênicos das sequencias de proteínas homólogas a Bm86. As análises filogenéticas foram feitas para determinar a extensão da divergência entre diferentes populações de R. microplus com o objetivo de identificar a sequência que poderia ser usada como vacina universal contra as múltiplas populações geograficamente distintas de R. microplus e espécies de carrapatos relacionados. Considerando-se a extensa sequência e o polimorfismo observados entre linhagens de R. microplus de diferentes regiões geográficas, podemos concluir que pode ser possível obter uma vacinação efetiva contra esses carrapatos bovinos utilizando um único antígeno universal baseado em Bm86.

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.