RESUMO
A new species of argasid tick, Ornithodoros (Alectorobius) rioplatensis Venzal, Estrada-Peña, & Mangold, is described from larval and adult specimens collected in Uruguay. Further specimens from Argentina, Paraguay, and Chile are ascribed to the new species. Key distinguishing characters of larvae of the species are the number of pairs of dorsal setae (19-20 but typically 20 in O. rioplatensis, compared with 16-17 but typically 17 in O. puertoricensis and O. talaje), and the length of the hypostome, which is clearly longer in O. rioplatensis than in O. talaje. Morphological details of the adults of these species are inadequate for taxonomic purposes. The genetic distance between O. puertoricensis and O. rioplatensis, based on 16S rDNA sequencing, is approximately 12.7%. Variability in some morphological features, using multivariate morphometric discrimination to assess congruence between populations, was examined among larval specimens of O. talaje and O. puertoricensis collected from the United States, and Central and South America. Larval specimens of O. talaje from Guatemala (near the type locality of the species) were morphologically different from Mexican and southern U.S. populations originally described as O. talaje. In the absence of DNA data for these populations, and because of inadequate statistical discrimination among body characters, we prefer to refer to the Mexican and U.S. material as O. nr. talaje until further analysis of population variability is conducted using an adequate sample size.
Assuntos
Ixodidae/classificação , Ixodidae/ultraestrutura , Animais , Feminino , Larva/classificação , Larva/ultraestrutura , Masculino , América do SulRESUMO
Amblyomma triste Koch, 1844, the tick species most frequently involved in human bites in Uruguay, has been implicated as a vector of human rickettsiosis. Seasonal abundance of adult A. triste was examined by standard flagging at three sites where human tick bites and cases of the disease have been reported. Adult tick activity occurred from August to February (end of winter to mid summer in the southern hemisphere) with a peak in spring. Activity declined in step with decreasing temperatures and photoperiod during winter. This period of activity coincides with seasonal outbreaks of human rickettsiosis in the region. In a small mammal survey, the Sigmodontinae rodents Scapteromys tumidus (Waterhouse, 1837) and Oxymycterus nasutus (Waterhouse, 1837) and the small marsupial Monodelphis dimidiata (Wagner, 1847) were the main hosts for immature A. triste. Immature ticks were observed on hosts in November, well within the period of peak adult abundance. In stored collections, immature ticks were most often collected from January to March. These data suggest that one generation might be completed in 1 year. The main animal host for adult A. triste at our study sites was the domestic dog. Humans were afflicted by the tick in rural and suburban settlements where other host animals are scarce or extinct and where dogs are common.
Assuntos
Vetores Aracnídeos/microbiologia , Ixodidae/microbiologia , Infecções por Rickettsia/epidemiologia , Rickettsia/fisiologia , Infestações por Carrapato/epidemiologia , Animais , Bovinos , Cães , Feminino , Cabras/parasitologia , Cavalos/parasitologia , Interações Hospedeiro-Parasita , Humanos , Leões/parasitologia , Masculino , Infecções por Rickettsia/microbiologia , Infecções por Rickettsia/parasitologia , Estações do Ano , Fatores de Tempo , Uruguai/epidemiologiaRESUMO
Twenty eight species of Ixodidae have been found on man in South America (21 Amblyomma, 1 Boophilus, 2 Dermacentor, 2 Haemaphysalis, 1 Ixodes and 1 Rhipicephalus species). Most of them are rarely found on man. However, three species frequently parasitize humans in restricted areas of Argentina (A. neumanni reported from 46 localities), Uruguay (A. triste from 21 sites) and Argentina-Brazil (A. parvum from 27 localities). The most widespread ticks are A. cajennense (134 localities in Argentina, Bolivia, Brazil, Colombia, Ecuador, French Guiana, Guyana, Paraguay, Suriname and Venezuela), A. ovale (37 localities in Argentina, Brazil, Ecuador, French Guiana, Guyana, Paraguay, Suriname and Venezuela) and A. oblongoguttatum (28 sites in Brazil, Colombia, French Guiana, Guyana, Suriname and Venezuela). Amblyomma aureolatum (18 localities in Argentina, Brazil, French Guiana and Paraguay), A. cajennense, and A. triste are vectors of rickettsioses to man in South America. A better understanding of the respective roles of these and other tick species in transmitting pathogens to humans will require further local investigations. Amblyomma ticks should be the main subjects of these studies followed by species of Boophilus, Dermacentor, Haemaphysalis and Rhipicephalus species. In contrast with North America, Europe and Asia, ticks of the genus Ixodes do not appear to be major players in transmitting diseases to human. Indeed, there is only one record of an Ixodes collected while feeding on man for all South America.
Assuntos
Vetores Aracnídeos/fisiologia , Ixodidae/fisiologia , Infecções por Rickettsia/transmissão , Infestações por Carrapato/parasitologia , Animais , Vetores Aracnídeos/classificação , Geografia , Humanos , Ixodidae/classificação , Infecções por Rickettsia/epidemiologia , América do Sul/epidemiologia , Infestações por Carrapato/epidemiologiaRESUMO
The female of Argas (Persicargas) keiransi Estrada-Peña, Venzal & González-Acuña (Acari: Argasidae) is described from specimens collected in the type locality in Chile. The female has a unique combination of characters in the dorsal cuticle and in the number and pattern of ventrolateral setae in the basis capituli. Additional features on tarsus I chaetotaxy and dorsal plate are provided for the larva of the species, as observed on flat specimens derived from engorged females collected in the type locality. Keys for the larvae of the New World Persicargas are provided as well as illustrations for prominent characters in hypostome and posterolateral setae. The mitochondrial 16S rDNA sequence of A. keiransi has been obtained, and an analysis of the phylogenetic relationships with other ticks is included. Phylogenetic analysis provides support for a Persicargas grouping of species, separated from species in Argas.
Assuntos
Argas/classificação , Argas/ultraestrutura , Filogenia , América , Animais , Argasidae/anatomia & histologia , Argasidae/classificação , Chile , Demografia , Feminino , Geografia , Larva/ultraestrutura , Dados de Sequência Molecular , RNA Ribossômico 16S/genética , Especificidade da EspécieRESUMO
In this study we use high-resolution satellite imagery to map habitat suitability for both Boophilus annulatus and B. microplus over an area covering parts of Texas and northeastern Mexico. The habitat for these tick species covers widely different regions. B. microplus finds satisfactory abiotic conditions in wet coastal habitats, whereas B. annulatus finds suitable habitat in the drier inner parts of southwestern Texas and northern Mexico; the two species have very different habitat requirements. We use habitat topology and data concerning abiotic habitat suitability to understand the effects of habitat configuration on tick abundance. This is achieved using traversability (habitat permeability) and recruitment (tick abundance at the patch level) to produce a model that computes the abundance of ticks at the patch level. Results from the computation are then compared with actual data on tick outbreaks at the Texas-Mexico border, as a test of the agreement between actual tick captures and abundance model predictions.
Assuntos
Doenças dos Bovinos/epidemiologia , Doenças dos Bovinos/parasitologia , Ixodidae/fisiologia , Comunicações Via Satélite , Infestações por Carrapato/veterinária , Animais , Bovinos , Ecossistema , Geografia , Incidência , México/epidemiologia , Modelos Biológicos , Modelos Estatísticos , Densidade Demográfica , Texas/epidemiologia , Infestações por Carrapato/epidemiologia , Infestações por Carrapato/parasitologiaRESUMO
We addressed the possible effects of several climate scenarios on habitat suitability (HS) for the cattle tick Boophilus microplus and the probability of producing permanent populations from introduced females of that tick in central parts of Argentina, using both a correlative model (derived from climate predictors) and a mechanistic (life cycle) model. There was high correlation (R2 = 0.866) between HS-derived and life cycle outputs for HS values higher than 0.52, suggesting that HS is a good estimator of the life cycle of the tick above a critical threshold of HS values. Scenarios with increased temperatures increased suitable habitats for the tick in southern parts of the study region, extending below parallel 34 degrees S, but suitable habitats remained limited in the west. A concurrent increase in rainfall produced a further increase of HS in these areas. Results from the life cycle model suggest that in areas of suitable habitat, permanent cattle tick populations are most probable if engorged females are introduced during mid-summer.
Assuntos
Ixodidae , Animais , Argentina , Clima , Simulação por Computador , Feminino , Modelos Teóricos , Dinâmica Populacional , Chuva , TemperaturaRESUMO
This paper focuses on the distribution of the cattle tick, Boophilus microplus, in Mexico. The study is aimed to understand the climate factors responsible of the recorded distribution that can statistically define the suitable habitat for the tick. Sites where the tick is recorded display significantly higher values of some climate variables in comparison with those where the tick is absent, namely mean monthly temperature (T) and atmospheric water vapour (W), yearly accumulated T, W and rainfall (R) (p < 0.001 for every variable), with smaller significance for the yearly sum of T/R and T/W ratios (p < 0.05). Interestingly, variables involving the Normalized Derived Vegetation Index (NDVI) do not shown statistical differences between the sites where the tick is present or absent. The best set of habitat-defining variables was integrated into a framework to assess the habitat suitability for the tick in Mexico. We used a point-to-point similarity metric to assign a classification value to a candidate site based on the proximity in environmental space of the most similar record site. A combination of 7 yearly and monthly values for temperature, rainfall and water vapour variables captured the tick distribution. Model performance, as tested with a separate set of distribution tests and defined by the AUC value, was 0.89. Causes of errors as detected with a visual comparison of both known and predicted distribution of the tick may be attributed to the use of a medium resolution, unable to capture locally important features of tick distribution, and to incomplete collections in some parts of the country.
Assuntos
Ecossistema , Ixodidae/fisiologia , Animais , Demografia , Umidade , México , Chuva , TemperaturaRESUMO
Listado de las especies de garrapatas de la región neotropical, que también presenta la distribución y los hospedadores preferenciales, las referencias para los estados posembrionarios, y los estadios aún sin escribir. También discute las enfermedades de los hombres y los animales derivadas de la infestación por garrapatas
Assuntos
Carrapatos/classificação , Argasidae , Ixodidae , Saúde Pública VeterináriaRESUMO
Listado de las especies de garrapatas de la región neotropical, que también presenta la distribución y los hospedadores preferenciales, las referencias para los estados posembrionarios, y los estadios aún sin escribir. También discute las enfermedades de los hombres y los animales derivadas de la infestación por garrapatas
Assuntos
Argasidae , Carrapatos/classificação , Ixodidae , Saúde Pública VeterináriaRESUMO
During routine collections between November 1999 and November 2002, three species of tick (Amblyomma tigrinum, Amblyomma triste and Rhipicephalus sanguineus) were found on humans in southern Uruguay. The finding of R. sanguineus and A. triste on humans is of particular concern because these tick species may be involved in the transmission of the pathogens causing human rickettsioses, a type of disease already known to occur in Uruguay.
Assuntos
Infestações por Carrapato/epidemiologia , Doenças dos Animais/parasitologia , Animais , Vetores Aracnídeos , Feminino , Humanos , Masculino , Infestações por Carrapato/parasitologia , Carrapatos , Uruguai/epidemiologiaRESUMO
Collections of Amblyomma auricularium (Conil 1878) and A. pseudoconcolor Aragão, 1908 are discussed in relation to distribution and hosts. Three tick collections (two from Argentina and a third from the USA) house a total of 574 A. auricularium (307 males, 162 females, 73 nymphs and 32 larvae) and 179 A. pseudoconcolor (96 males, 74 females, 4 nymphs and 5 larvae). Apart from an adult A. pseudoconcolor found on a bird, Nothura maculosa Temminck, 1815, all ticks were found on mammals. The great majority of specimens of both ticks species were removed from the family Dasypodidae Gray, 1821 (84.9% and 93.8% of A. auricularium and A. pseudoconcolor, respectively). Amblyomma auricularium has also been found on wild hosts of the families Myrmecophagidae and occasionally Didelphidae, Caviidae, Chinchillidae, Hydrochaeridae, Muridae, Canidae, Mustelidae, Procyonidae and domestic animals (cattle, dogs, horses), while A. pseudoconcolor has also been found occasionally on wild hosts of the family Didelphidae and on domestic animals (cattle, dogs). Amblyomma pseudoconcolor appears to be restricted to the Neotropical region, covering northern Argentina and the eastern region of South America from Uruguay to Surinam, including south-eastern Paraguay, eastern Brazil and French Guiana. Amblyomma auricularium is distributed from northern Patagonia in Argentina throughout the Neotropics into the Nearctic region up to the southern USA (Texas, Florida), with collection localities also in Belize, Bolivia, Brazil, Colombia, Costa Rica, French Guiana, Honduras, Mexico, Nicaragua, Panama, Paraguay, Trinidad & Tobago, Uruguay and Venezuela. It is not known whether A. auricularium is an established resident of the USA.
Assuntos
Tatus/parasitologia , Ixodidae/crescimento & desenvolvimento , Animais , América Central , Feminino , Florida , Ixodidae/classificação , Masculino , México , América do SulRESUMO
DNA sequences of Amblyomma aureolatum (Pallas, 1772) and Amblyomma ovale Koch, 1844 were obtained to determine genetic differences between these tick species. Collections of these species are discussed in relation to distribution and hosts. Seven ticks collections (four from Brazil, one from Argentina, one from Uruguay and one from USA) house a total of 1272 A. aureolatum (224 males, 251 females, 223 nymphs and 574 larvae) and 1164 A. ovale (535 males, 556 females, 66 nymphs and 7 larvae). The length of the sequenced mitochondrial 16S rRNA gene fragment for A. aureolatum was 370bp and for A. ovale was 373bp. The DNA sequence analysis showed a 13.1% difference between the two species. Apart from one male A. ovale found on a toad, all adult ticks were found on mammals. The majority of adult specimens of both tick species were removed from Carnivora (96.1 and 84.3% of A. aureolatum and A. ovale, respectively), especially from dogs (53.1% of A. aureolatum, and 46.4% of A. ovale). Collections on wild Canidae were higher for A. aureolatum (23.3%) than for A. ovale (7.1%). On the other hand, collections of A. ovale adults on wild Felidae were higher (18.3%) than findings of A. aureolatum (9.2%). The contribution of other mammalian orders as hosts for adults of A. aureolatum and A. ovale was irrelevant, with the exception of Perissodactyla because Tapiridae contributed with 13.0% of the total number of A. ovale adults. Adults of both tick species have been found occasionally on domestic hosts (apart of the dog) and humans. Most immature stages of A. aureolatum were found on Passeriformes birds, while rodents and carnivores were the most common hosts for nymphs and larvae of A. ovale. A. aureolatum has been found restricted to the Neotropical region, covering the eastern area of South America from Uruguay to Surinam, including northeastern Argentina, eastern Paraguay, southeastern Brazil and French Guiana. A. ovale showed a distribution that covers the Neotropical region from central-northern Argentina throughout the Neotropics into the Nearctic region of Mexico with a few records from the USA, also with collection sites in Paraguay, Bolivia, most Brazilian states, Peru, Ecuador, French Guiana, Surinam, Guyana, Trinidad & Tobago, Venezuela, Colombia, Panama, Costa Rica, Nicaragua, Belize, Guatemala and several states of Mexico.
Assuntos
Animais Domésticos/parasitologia , Animais Selvagens/parasitologia , DNA Ribossômico/genética , Ixodidae/genética , RNA Ribossômico 16S/genética , Animais , Sequência de Bases , DNA/química , DNA/genética , Ecossistema , Feminino , Ixodidae/classificação , Ixodidae/fisiologia , Masculino , Dados de Sequência Molecular , Reação em Cadeia da Polimerase , RNA Ribossômico 16S/química , Homologia de Sequência do Ácido NucleicoRESUMO
The larva of Argas (Persicargas) keiransi Estrada-Peña, Venzal & González-Acuña n. sp. is described from specimens collected on the neck of a chimango, Milvago c. chimango (Aves: Falconiformes) in the Chillán, Chile, in the Sub-Antarctic biogeographical region. The larva of the new species shares the tarsus I setal formula with A. (P.) giganteus, these being the only two Persicargas species with three pairs of ventral setae plus both av4 and pv4 setae. However, it is unique in having a dorsal plate "V" or "U" shaped, with the anterior end open, without the typical reticulated pattern present in the remaining species of the genus.
Assuntos
Doenças das Aves/parasitologia , Aves/parasitologia , Infestações por Carrapato/veterinária , Carrapatos/patogenicidade , Animais , Larva , Carrapatos/crescimento & desenvolvimento , Carrapatos/ultraestruturaRESUMO
Remote sensing on the basis of AVHRR (advanced very high resolution radiometer) satellite imagery was used, together with standard geostatistical methods (cokriging), to estimate the distribution of habitat suitability (HS) for the tick Boophilus microplus (Canestrini) in Central America. Most attention was paid to the expected limits of tick distribution as well as the temperature and vegetation values responsible for different HS zones and their variability within the year. The highest HS extended through wide areas of southeastern United States, much of Mexico, and other countries of Central America. Areas with higher HS had relatively stable temperatures (within 20-25 C) throughout the year, and had a NDVI (normalized derived vegetation index) of around 0.4. These areas need to be targeted to ensure acaricide usage at optimum intervals and to avoid the formation of areas with enzootic instability. A seasonal analysis of the climate trend through the study period (1982-1999) revealed a warming cycle, together with a rise in NDVI index values. The main consequence of this trend is the gradual increase in unsuitability in areas where the tick is already established, with the establishment of new foci in zones currently too cold to support tick populations. The cooling periods of 1-2 yr that were observed between warming cycles may also lead to enzootic instability when warm zones cool to within the suitability range. As the model is remotely sensed, a continuous update of the B. microplus distribution could be performed, assuring maximum efficiency in developing management strategies.
Assuntos
Meio Ambiente , Efeito Estufa , Carrapatos/crescimento & desenvolvimento , Animais , América Central , México , Modelos Biológicos , Comunicações Via Satélite , Estações do Ano , Sudeste dos Estados Unidos , TemperaturaRESUMO
Remote sensing based on NOAA (National Oceanographic and Atmosphere Administration) satellite imagery was used, together with geostatistics (cokriging) to model the correlation between the temperature and vegetation variables and the distribution of the cattle tick, Boophilus microplus (Canestrini), in the Neotropical region. The results were used to map the B. microplus habitat suitability on a continental scale. A database of B. microplus capture localities was used, which was tabulated with the AVHRR (Advanced Very High Resolution Radiometer) images from the NOAA satellite series. They were obtained at 10 days intervals between 1983 and 1994, with an 8 km resolution. A cokriging system was generated to extrapolate the results. The data for habitat suitability obtained through two vegetation and four temperature variables were strongly correlated with the known distribution of B. microplus (sensitivity 0.91; specificity 0.88) and provide a good estimation of the tick habitat suitability. This model could be used as a guide to the correct interpretation of the distribution limits of B. microplus. It can be also used to prepare eradication campaigns or to make predictions about the effects of global change on the distribution of the parasite.
Assuntos
Vetores Aracnídeos/crescimento & desenvolvimento , Doenças dos Bovinos/prevenção & controle , Modelos Biológicos , Comunicações Via Satélite , Carrapatos/crescimento & desenvolvimento , Animais , Bovinos , Clima , Bases de Dados como Assunto , Previsões , Temperatura Alta , Plantas , América do SulRESUMO
Attacks by adult stages of the soft tick Argas (Argas) neghmei (Acari: Argasidae) on inhabitants of the High Andean plateau of Argentina are reported. This is the first local report of this species, which was previously found in the north of Chile. Taxonomic differences between A. (A.) neghmei and other neotropical and exotic species of the genus are underlined. The status of the knowledge about the Argentine argasid fauna is briefly described.
Assuntos
Carrapatos/classificação , Animais , ArgentinaRESUMO
Gas chromatography has been used to analyze the variation in cuticular hydrocarbon patterns between several populations of Amblyomma cajennense. 88 compounds were detected and these could be divided into 17 groups of hydrocarbons. Heterozygosis in the populations ranges from 0% to 25.84%. Isomers for pentacosane, heptacosane and nonatriacontane are the most variable, with 13, 10 and 11 variants, respectively. Nei's genetic identity and genetic distance show that populations may be considered as regional variants of only one species: the results do not indicate the presence of sibling species. However, a relatively high genetic distance has been observed between several Cuban and continental populations, suggesting a long reproductive isolation. Gas chromatography of cuticular hydrocarbons is a good alternative to isozyme analysis for population studies, when collecting conditions do not allow the use of live ticks and only alcohol-preserved collections are available. The high number of compounds available for genetic studies will provide excellent markers for evaluating the extent of gene flow and migration of tick species.